Du fait de leurs propriétés immunostimulantes, les entérotoxines de Staphylococcus aureus (SEs) sont aussi considérées comme des outils thérapeutiques anticancéreux potentiels. Cependant, leurs implications dans de nombreuses pathologies humaines limitent leurs utilisations. Récemment, un opéron dénommé enterotoxin gene cluster (egc) codant pour cinq entérotoxines (SEG, SEI, SElM, SElN et SElO) supposées être de moindre virulence pour l’organisme, a été mis en évidence. En 2004, des patients atteints de carcinome broncho-pulmonaire ont été traités par l’administration d’un surnageant de culture d’une souche de S. aureus, contenant l’opéron egc. Ce traitement a permis d’allonger la durée de survie, et n’a eu aucun effet secondaire. Dans ce cadre, l’objectif de cette thèse a été d’étudier l’activité anti-tumorale des toxines de l’egc. Nos travaux ont mis en évidence l’activité tumoricide de ces toxines, induite par l’activation du système immunitaire. Cette toxicité est médiée par la sécrétion de nombreux médiateurs solubles comme le TNF-α et le NO. Nous avons confirmé le caractère pro-inflammatoire de type Th1 des toxines de l’egc. Nos travaux ont également montré qu’hormis SEI, les toxines de l’egc induisent des sécrétions de cytokines, chimiokines, protéases matricielles (MMPs) et facteurs de croissances nettement inférieures à celle induites par le reste des SEs. Ces résultats pourraient expliquer la faible toxicité associée aux toxines de l’egc. Enfin, nous avons montré que SElO possèdent une toxicité intrinsèque vis-à-vis des lignées tumorales. Cette étude plaide en faveur de l'intérêt des toxines de l’egc dans le développement de nouvelles approches en thérapie anti-tumorale / The use of classical superantigens (e.g. SEA, SEB and SEC) for treatment of cancer has resulted in a low response rates due to serious toxicity in humans. However, in a recent clinical study, remarkable results in treating lung cancer were obtained using superantigens encoded by the enterotoxin gene cluster (egc) without causing any significant toxicity. The current study was performed to investigate how egc superantigens (i.e. SEG, SEI, SElM, SElN and SElO) have tumoricidal activity with low toxicity. Indeed, we first demonstrated that tumoricidal activity of egc-SEs is mediated by immune cell activation, in particular, by secretion of soluble mediators such as nitric oxide and TNF-α. Thus, the proteomic analysis of the PBMC supernatants, showed that SEs-egc enhance the expression of pro-inflammatory cytokines, chimokines and many other biomarkers. Interestingly, levels were significantly higher in supernatants of SEA-stimulated PBMC than those with egc superantigens suggesting that staphylococcal superantigens differs in their inflammatory proprerties. Our results suggest that the relative lower pro-inflammatory activity of egc toxins may explain the low toxicity of these toxins observed during the clinical trial. Finally, we showed that SElO have a direct cytostatic activity against tumor cells. These findings suggest that egc-SEs seems to be good candidates for the development of new drugs in cancer therapy

Submitted by Adriana Martinez (amartinez@unoeste.br) on 2017-09-04T20:00:15Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Marilda.pdf: 696658 bytes, checksum: 0c0c3380d242fc97692b0a24713bda46 (MD5) / Made available in DSpace on 2017-09-04T20:00:15Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Marilda.pdf: 696658 bytes, checksum: 0c0c3380d242fc97692b0a24713bda46 (MD5) Previous issue date: 2017-04-20 / In order for food to provide, maintain or recover health it is necessary that it presents satisfactory sanitary control. It is known that one of the possible causes of hospital infection is the consumption of contaminated food, thus, providing safe food is essential to hospital nutrition services. Among foodborne diseases, those of bacterial origin have been pointed out as the most widespread public health problem in the world, especially Staphylococcus aureus, bacteria found mainly in the nasal cavities, mouth and skin of the human population. In this context, contamination of food, handlers and utensils is an important link among food, patients and diseases transmitted by food. Therefore, the the objective of this is study is to investigate the presence of S. aureus in food handlers, equipment, counter tops and utensils of a hospital's nutrition service, as well as the resistance profile of the isolated for antimicrobials. Samples of the environment, hands and nasal mucosa of employees of a nutrition service were collected with two sterile swabs in two different periods of the year (March and June), resulting in a total of 134 samples, which were submitted to characterization tests Biochemistry and morphotinorial (staining of gram, catalase and coagulase tests in tube), phenotypic evaluation by drug diffusion technique and D-test approach, in addition to the phenotypic biofilm characterization using Congo Red Agar. The results showed that the utensils, equipment and food handlers of the investigated hospital had high rates of colonization by S. aureus, mainly in the food production sector. It was also observed the high frequency of antimicrobial resistance, mainly erythromycin and the presence of multi-resistant microorganisms. A large number of positive samples were also found for the biofilm production, with totality for the samples of manipulators. We highlight the relevance of the data in virtue to the serious consequences and risks that can be triggered in the hospital environment. Educational actions and awareness measures were proposed in the institution, aiming at patient safety. / Para que a alimentação possa proporcionar, manter ou recuperar a saúde é necessário que a mesma apresente controle higiênico sanitário satisfatório. Sabe se que uma das possíveis causas de infecção hospitalar é o consumo de alimentos contaminados, sendo assim, fornecer alimentos seguros é essencial aos serviços de nutrição hospitalares. Das doenças transmitidas por alimentos, as de origem bacteriana são apontadas como o problema de saúde pública mais abrangente no mundo com destaque para Staphylococcus aureus, bactéria encontrada principalmente nas fossas nasais, boca e pele da população humana. Neste contexto, a contaminação de alimentos, manipuladores e utensílios é um importante elo entre alimento, pacientes e doenças transmitidas por alimentos. Diante disto, o presente estudo teve como objetivo investigar a presença de S. aureus nos manipuladores de alimentos, equipamentos, bancadas e utensílios do serviço de nutrição de um hospital, bem como o perfil de resistência dos isolados a antimicrobianos. Foram coletadas, com auxílio de swabs estéreis, amostras do ambiente, mãos e mucosa nasal de funcionários de um serviço de nutrição em dois períodos diferentes do ano (março e junho), resultando num total de 134 amostras, que foram submetidas a testes de caracterização bioquímica e morfotintoriais (coloração de gram, provas de catalase e coagulase em tubo), avaliação fenotípica por técnica de difusão da droga e teste de aproximação de discos-teste D, além da caracterização fenotípica de biofilme utilizando Ágar Vermelho Congo.. Os resultados demonstraram que os utensílios, equipamentos e manipuladores de alimentos do hospital investigado apresentaram altas taxas de colonização por S. aureus principalmente no setor de produção de refeições (cozinha). Foi observada também a alta frequência de resistência a antimicrobianos, principalmente a eritromicina e a presença de micro-organismos multirresistentes. Constatou-se também grande número de amostras positivas para a produção de biofilme, com totalidade para as amostras isoladas de manipuladores. Destacamos a relevância dos dados encontrados em virtude das graves consequências e riscos que podem desencadear no ambiente hospitalar. Ações educativas e medidas de conscientização foram propostas na instituição, visando à segurança do paciente.

Antibodies have become indispensable tools in diagnostics, research and as therapeutics. There are several strategies to generate monoclonal antibodies (mAbs) in order to avoid the drawbacks of polyclonal antibodies (pAbs) for therapeutic use. Moreover, the growing interest in precision medicine requires a well-characterized target and antibody to predict the responsiveness of a treatment. This thesis describes the use of epitope information and display technologies to generate and characterize antibodies. In Paper I, we evaluated if the epitope information of a well-characterized pAb could be used to generate mAbs with retained binding characteristics. In Paper II, the epitope on the complement protein C5 towards Eculizumab was mapped with surface display, the results of which explained the non-responsiveness of Eculizumab treatment among a patient group due to a mutated C5 gene. With this in mind, we showed efficacy in treatment of the mutated C5 variants using a drug binding to another site on C5, suggesting that our approach can be used to guide treatment in precision medicine. In Paper III, a Gram-positive bacterial display platform was evaluated to complement existing platforms for selection of human scFv libraries. When combined with phage display, a thorough library screening and isolation of nano-molar binders was possible. In Paper IV, a solid phase method for directed mutagenesis was developed to generate functional affinity maturation libraries by simultaneous targeting of all six CDRs. The method was also used to create numerous individual mutants to map the paratope of the parent scFv. The paratope information was used to create directed libraries and deep sequencing of the affinity maturation libraries confirmed the viability of the combination approach. Taken together, precise epitope/paratope information together with display technologies have the potential to generate attractive therapeutic antibodies and direct treatment in precision medicine. / <p>QC 20170418</p>

Notre travail montre la prédominance du clone « Lyon » parmi les souches de Staphylococcus aureus responsables d’infections invasives (i.e. bactériémies). Il est caractérisé par la présence du gène codant la «staphylococcal enterotoxin » (SE) A. Afin de mieux comprendre le lien éventuel entre la prédominance de la SEA et la gravité des infections induites, nous avons orienté nos travaux sur le versant immuno‐inflammatoire des SE. L’étude des répertoires Vβ induits par l’ensemble des SE s’est révélée peu discriminante. A l’aide d’approches génomiques et protéiques réalisées sur des lymphocytes et monocytes humains, nous avons observé le puissant potentiel inflammatoire de la SEA en particulier par rapport à la SEG (SE appartenant à l’opéron egc retrouvé dans les infections de faible sévérité) et la prédominance de la réponse lymphocytaire T. Enfin, afin de mieux comprendre la spécificité des effets observés, nous avons conduit des expériences sur lymphocytes purifiés en ciblant les Ly T effecteurs (CD4+CD25‐) et Ly T régulateurs (CD4+CD25+FOXP3+). Nos travaux ont confirmé l’induction par la SEA d’une forte réponse inflammatoire, associant une synthèse de cytokines de type Th1 et Th17 dans les deux lignées lymphocytaires. De plus, nos résultats suggèrent que les SE provoquent une perte des fonctions suppressives des Ly T régulateurs ouvrant de nouvelles perspectives quant à l’implication des SAgs dans de nombreuses situations cliniques en particulier le choc septique, et les infections chroniques / Our work shows the prevalence of the “Lyon” clone among Staphylococcus aureus strains responsible for severe systemic infections (i.e. bacteremia). This clone is characterized by the presence of the staphylococcal enterotoxin (SE) A coding gene. To better understand the possible link between the prevalence of SEA and the severity of infections, we focused our work on the immuno inflammatory responses of SE. By using genomic and protein studies, in human lymphocytes and monocytes, we observed the potent inflammatory property of SEA (especially in comparison with SEG ‐ belonging to the egc cluster mainly found in less severe infections) mainly targeting T cell response over monocytes. Finally, to better understand the specificity of these effects, we performed experiments on purified lymphocytes and targeted effectors (CD4+CD25‐) and regulatory T lymphocytes (CD4+CD25+FOXP3+). Our works confirmed the induction by SEA of a strong inflammatory response, characterized by the release of Th1 and Th17 cytokines in both lymphocyte lineages. Furthermore, our results also showed the loss of the regulatory T cell suppressive functions after SE stimulation. Collectively, these results offer new perspectives for the implication of the SAgs in numerous clinical situations in particular toxic shock and the chronic infections.

La plasticité génomique de Staphylococcus aureus lui permet d’acquérir des gènes codant des facteurs de virulence mais aussi des gènes de résistance aux antibiotiques, notamment la cassette de résistance à la méticilline (SCCmec). La résistance à la méticilline est d’abord apparue dans des souches hospitalières à l’origine de grands clones pandémiques nosocomiaux, puis a ensuite émergé en milieu communautaire chez des souches virulentes possédant la leucocidine de Panton-Valentine. Nous avons observé en 2002, en milieu hospitalier et communautaire, l’émergence inquiétante de S. aureus résistant à la méticilline (SARM) portant le gène tst de la toxine du choc toxique staphylococcique (TSST-1). Notre travail a consisté à : (i) l’élaboration de nouveaux outils contribuant à la description de clones de SARM, notamment d’un outil de typage de la cassette SCCmec, (ii) la caractérisation phénotypique et moléculaire de ce nouveau clone, (iii) l’étude de l’épidémiologie de ce clone, (iv) l’exploration de la pathogénie de ce clone en recherchant les propriétés génétiques qui lui confèrent une telle virulence et épidémicité, et notamment en identifiant le rôle de la TSST-1. Le clone de SARM tst+ est un clone épidémique de fond génétique ST5 en Multi Locus Sequence yping, atteignant principalement les sujets jeunes, et responsable d’infections variées à la fois toxiniques et suppuratives. Il est doté d’une cassette SCCmec atypique de type I tronquée dont le rôle dans le potentiel épidémique et de virulence de ce clone reste à déterminer. Enfin, la TSST-1 ne semble pas jouer un rôle déterminant, direct ou indirect, dans la pathogénie pléiotropique de ce clone / The plasticity of the Staphylococcus aureus genome confers to this specie the ability to gain accessory genes encoding virulence factors as well as antibiotic resistance determinants such as Staphylococcal cassette chromosome mec SCCmec that encodes methicillin-resistance. Methicillin resistance first emerged in hospital-acquired strains originally of successful nosocomial pandemic clones, and is also risen in virulent community-acquired strains containing the Panton-Valentine leucocidin. In 2002, we observed the worrying emergence of a new methicillin-resistant S. aureus (MRSA) clone that contains the tst gene encoding toxic shock syndrome toxin (TSST-1) responsible for both hospital and community-acquired infections. Our study was focused on: (i) new tools for MRSA description, mainly on a SCCmec typing tool, (ii) the characterisation of this new clone by molecular and phenotypic methods, (iii) the epidemiology of this clone, (iv) the pathogenic potential of this clone and the investigation of the genetic features that enhance transmission and virulence, particularly the role of TSST-1. The tst+ MRSA clone is an epidemic clone of genetic background ST5 by multilocus sequence typing that occurs mainly in young people and is responsible for a wide diversity of clinical syndromes including toxin-mediated and suppurative diseases. This clone harbours a peculiar cassette “truncated SCCmec type I” which could play an important role in virulence and transmission but are still under investigation. TSST-1 does not play a determining role (either directly or indirectly) in the pleiotropic pathogenesis of this clone

Therapeutische Erfolge von IVIG sind gut dokumentiert, aber die zu Grunde liegenden molekularen Mechanismen sind noch nicht vollständig erforscht. Molekulare Analysen unseres Labors über die Interaktion von IVIG mit Fabs von Patienten, die an einer autoimmunen Thrombozytopenie (ITP) leiden zeigten, dass die am häufigsten selektierten Fab von den V3-23 und V3-30 VH-Keimbahngenen abstammten. Eine weitere Studie mit IgG und IgM Phagen-Display Bibliotheken von einem gesunden Spender zeigten ebenfalls eine bevorzugte Reaktivierung von IVIG mit Fabs vom Ursprung der V3-23 und V3-30 Gene. Es konnte gefolgert werden, dass diese Interaktion von IVIG mit Fabs von diesen zwei VH-Genen weder alleine auf den Gesundheitsstatus des Spenders zurückzuführen war, noch auf eine zuvor erfolgte Behandlung mit IVIG. Diese Dissertation wurde unter Verwendung der Phagen-Display Technologie unternommen, um die molekulare Interaktion von IVIG mit Antikörpern zu erforschen, die von einem Patienten kloniert wurden, der an einem systemischen Lupus erythematodes und rheumatischem Fieber leidet. Die Resultate waren mit den früheren Studien zu vergleichen, insbesondere mit den Daten eines Patienten, der zu der ITP einen Lupus entwickelte. 23 Fabs, welche 7 unabhängige Klone repräsentierten, wurden isoliert. Im Gegensatz zu von Patienten mit ITP abstammenden Klonen reagierte keines von den in dieser Studie selektierten Fabs mit Thrombozyten. Die über IVIG gebundene Fab-Phagen stammten hierbei ausschließlich von den V3-23 und V3-30 VH-Genen ab. Darüber hinaus wurde beobachtet, dass von diesen Fabs verschiedene CDR3 Regionen einschließlich verschiedenen D- und JH-Gensegmenten benutzt wurden. Die Ergebnisse zeigten weiterhing, dass die Bindung von IVIG an die Fabs unabhängig von der Leichten Kette war. Ihrem Keimbahngen-Ursprung entsprechend hatten die Fabs Aminosäuren an Positionen in den FR1, FR3 und im 3'-Ende von CDR2, die dafür bekannt sind, dass sie für die Bindung des B-Zell-Superantigens Staphylococcus Protein A (SpA) essentiell sind. Es wurde gezeigt, dass sich zwar einige von den Fabs stark an SpA banden, aber keine Korrelation in der Intensität zur Bindung mit IVIG vorlag. Einige Fabs zeigten eine schwache Bindung an HIV gp120, einem anderen B-Zell-Superantigen. Zusammenfassend lässt sich aus der vorliegenden Studie und den vorherigen Ergebnissen schließen, dass ein Anteil von IVIG wie ein B-Zellen Superantigen funktionieren könnte, das für die Bildung und Regulation des normalen B-Zellen Repertoires wichtig ist. Der Bindungsmechanismus scheint ähnlich, aber nicht identisch mit dem der anderen getesteten B-Zellen-Superantigene zu sein. / The beneficial therapeutic effects of IVIG are well documented, but the underlying molecular mechanisms are not fully understood. Recent investigations from our laboratory into the molecular analysis of Fabs bound by IVIG from patients suffering from autoimmune thrombocytopenia revealed that the most frequently selected Fabs originated from the V3-23 and V3-30 VH germline genes. A subsequent study with IgG and IgM phage display libraries from a healthy donor also demonstrated a preferential reactivity of IVIG to Fabs of V3-23 and V3-30 origin. That study revealed that the unique reactivity of IVIG to Fabs of these two VH gene loci was not restricted to the autoimmune nature of the donors, neither to previous treatment with IVIG. One of the thrombocytopenia patients developed lupus. This study was undertaken to study the molecular interaction of IVIG with antibodies selected from a patient suffering from systemic lupus erythematosus and rheumatic fever using phage display technology, and to compare the results with the previous studies. Twenty-three Fabs representing seven independent clones were isolated. In contrast to ITP-derived clones, none of the Fabs selected in this study reacted with platelets. The Fab phages bound by IVIG were sequenced in order to determine their VH gene usage and clonal relatedness. V3-23 and V3-30 VH genes were found to be exclusively utilized by the Fab phages bound by IVIG. Moreover, different CDR3 regions including different D and JH gene segments were observed to be used by these Fabs. The results further showed that the binding of IVIG to the Fabs was independent of the light chain since different light chains were observed to be associated with the VH3 immunoglobulins. Detailed sequence analysis of the Fabs revealed the presence of amino acid residues at positions within FR1, FR3, and the 3' end of CDR2 that are known to be contacted by the B cell superantigen Staphylococcus protein A (SpA). Some of the Fabs were shown to bind strongly to SpA, but there was no correlation with the binding-intensity to IVIG. Some bound very weakly to HIV gp120, another B cell superantigen. This study, together with previous results, suggests that a subset of IVIG may function as a B cell superantigen that may significantly shape the B cell repertoire. The binding mechanism appears to be similar but not identical to the other tested B cell superantigens.

As condições de produção de queijos frescos são favoráveis à ocorrência e à produção de enterotoxinas produzidas por estafilococos, sendo estes os principais micro-organismos relacionados aos casos de intoxicação alimentar no mundo, tornando-se necessários estudos sobre a rastreabilidade das fontes de contaminação durante a fabricação, identificação genotípica e habilidade de cepas em produzir enterotoxinas. Este trabalho teve como objetivo isolar e identificar estafilococos positivos para o teste de coagulase, potencialmente produtores de enterotoxinas em laticínios do estado de São Paulo, desde o leite recebido até o produto final. A técnica da mPCR foi utilizada para identificar três espécies de Staphylococcus coagulase-positiva (S. aureus, S. hyicus e S. intermedius) entre os isolados obtidos de diferentes pontos de processamento em laticínios do Estado de São Paulo. O perfil genético das cepas foi avaliado através da comparação de bandas pela técnica Enterobacteria Repetitive Intergenic Consensus (ERIC-PCR) e graficamente demonstrados por um dendrograma. O DNA de 102 cepas isoladas, de amostras de leite cru, leite pasteurizado, coágulo, manipulador, superfícies de equipamentos de laticínios do Estado de São Paulo e queijos foi extraído e submetido à reação em cadeia da polimerase (PCR), utilizando-se primers específicos para a detecção de fragmentos dos genes envolvidos na síntese das toxinas (SE) do tipo A, B, C, D, E, G, H, I e J. Das 102 cepas avaliadas, 5 apresentaram amplificação do fragmento do gene responsável pela codificação da toxina A, 3 para toxina C, 56 para toxina G, 59 para toxina H, 9 para toxina I, e nenhuma para toxinas B, D, E e J. Amostras de leite cru, leite pasteurizado e queijos produzidos nos laticínios e dos isolados de Staphylococcus spp. coagulase positiva que apresentaram ao menos algum dos genes relacionados à produção de toxinas clássicas (A, B, C, D e E) foram submetidos a um teste de detecção de enterotoxinas pelo sistema VIDAS® Staph Enterotoxin (SET2). Os dados obtidos para a identificação molecular das cepas, da ocorrência de cepas portadoras dos genes relacionados à produção de enterotoxinas e da produção fenotípica das enterotoxinas foram submetidos ao teste qui-quadrado. O presente trabalhou confirmou que o risco de intoxicação estafilocócica é real, pois foi encontrada enterotoxina em amostras de leite pasteurizado e queijos. / The production conditions of fresh cheese are favorable to the occurrence and production of enterotoxin produced by Staphylococci, which are the main microorganisms related to food poisoning cases in the world, requiring studies to trace the sources of contamination during manufacturing and genotypic identification ability of strains to produce enterotoxin. This study aimed to isolate and identify staphylococci positive for coagulase test, potentially producing enterotoxins in dairy products in the state of São Paulo, from milk receiving to final product. In three dairy producers of Minas fresh cheese, samples were collected from various points in the manufacturing process. the technique of mPCR was used to identify three coagulase-positive species (S. aureus, S. hyicus and S. intermedius) between isolates from different points of a processing dairy in the state of São Paulo. The genetic profile of the strains were evaluated by comparing the bands through the technique Enterobacteria Repetitive Intergenic Consensus (ERIC-PCR) and were graphically displayed by a dendrogram. The DNA of 102 strains isolated from samples of raw milk , pasteurized milk , curd, handler and equipment surface from dairies in São Paulo State and cheese were subjected to the polymerase chain reaction (PCR), using primers for the detection of specific fragments of the genes involved in the synthesis of toxins (SE) of type A, B , C , D, E, G , H, I and J. Of the 102 strains tested, five showed amplification of the gene fragment encoding toxin A, three for toxin C , 56 to toxin G, 59 to toxin H, 9 to toxin I, and none for toxins B D, E and J. For confirmation, each isolated strain carrying at least some of the genes related to the production of classical enterotoxinas, cheese and milk samples was subjected to detection by enterotoxigenic VIDAS® Staph Enterotoxin II (VIDAS SET2) bioMérieux. This identification reinforces the need to adopt proper hygiene practices in the dairy, avoiding thus the spread of these microorganisms and the possible production of enterotoxin . The data obtained for the molecular identification of the strains, the occurrence of strains carrying the genes related to the production of enterotoxin production and phenotypic enterotoxins were subjected to the Chi-squared test. This work confirmed that the risk of staphylococcal food poisoning is real, because enterotoxin was found in samples of pasteurized milk and cheeses.

HTML clipboard The great advances in DNA technology, e.g. sequencing and recombinant DNA techniques, have given us the genetic information and the tools needed to effectively produce recombinant proteins. Recombinant proteins are valuable means in biotechnological applications and are also emerging as alternatives in therapeutic applications. Traditionally, monoclonal antibodies have been the natural choice for biotechnological and therapeutic applications due to their ability to bind a huge range of different molecules and their natural good affinity. However, the large size of antibodies (150 kDa) limits tissue penetration and the recombinant expression is complicated. Therefore, alternative binders with smaller sizes have been derived from antibodies and alternative scaffolds. In this thesis, two structurally similar domains, Zbasic and ABDz1, have been used as purification tags in different contexts. They are both three-helical bundles and derived from bacterial surface domains, but share no sequence homology. Furthermore, by redesign of the scaffold used for ABDz1, a molecule intended for drug targeting with extended in-vivo half-life has been engineered. In Papers I and II, the poly-cationic tag Zbasic is explored and evaluated. Paper I describes the successful investigation of Zbasic as a purification handle under denaturating conditions. Moreover, Zbasic is evaluated as an interaction domain in matrixassisted refolding. Two different proteins were successfully refolded using the same setup without individual optimization. In Paper II, Zbasic is further explored as a purification handle under non-native conditions in a multi-parallel setup. In total, 22 proteins with varying characteristics are successfully purified using a multi-parallel protein purification protocol and a robotic system. Without modifications, the system can purify up to 60 proteins without manual handling. Paper I and II clearly demonstrate that Zbasic can be used as an interaction domain in matrix-assisted refolding and that it offers a good alternative to the commonly used His6-tag under denaturating conditions. In paper III, the small bifunctional ABDz1 is selected from a phage display library. Endowed with two different binding interfaces, ABDz1 is capable of binding both the HSA-sepharose and the protein A-derived MabSelect SuRe-matrix. The bifunctionality of the domain is exploited in an orthogonal affinity setup. Three target proteins are successfully purified using the HSA-matrix and the MabSelect SuRe-matrix. Furthermore, the purity of the target proteins is effectively improved by combining the two chromatographic steps. Thus, paper III shows that the small ABDz1 can be used as an effective purification handle and dual affinity tag without target specific optimization. Paper IV describes the selection and affinity maturation of small bispecific drug-targeting molecules. First generation binders against tumor necrosis factor-α are selected using phage display. Thereafter on-cell surface display and flow cytometry is used to select second-generation binders. The binding to tumor necrosis factor-α is improved up to 30 times as compared to the best first generation binder, and a 6-fold improvement of the binding strength was possible with retained HSA affinity. Paper III and IV clearly demonstrate that dual interaction surfaces can successfully be grafted on a small proteinaceous domain, and that the strategy in paper IV can be used for dual selection of bifunctional binders. / <p>QC20100610</p>

The engineering of bacterial surfaces has in recent yearsattracted a lot of attention with applications in manydifferent areas of bioscience. Here we describe the use of twodifferent surface display systems for the gram-positivebacteria Staphylococcus carnosus and Staphylococcus xylosus invarious biotechnological applications. Environmental microbiology currently attracts a lot ofattention since genetically engineered plants and bacteriamight be used as bioadsorbents for sequestration of toxicmetals. Bacterial surface display of metal-binding peptidesmight enable recycling of the biomass by desorption ofaccumulated heavymetals. In an attempt to recruitstaphylococcal display systems for bioremediation purposes,polyhistidyl peptides were successfullly displayed on thesurface of recombinant S. carnosus and S. xylosus cells.Whole-cell Ni2+-binding assays demonstrated that therecombinant cells had gained metal-binding capacity compared towild-type cells. Tailor-made, metal-binding staphylococci was created using apreviously constructed phage-display combinatorial proteinlibrary based on a fungal cellulose-binding domain (CBD)derived from the cellobiohydrolase Cel7A of Trichoderma reseii.Novel metal-binding CBDs were generated through a phagemediated selection procedure. Selected CBD variants, now devoidof cellulose binding, were randomly selected and sequenceanalysis of selected variants revealed a marked preference forhistidine residues at the randomized positions. Surface displayof these novel CBD variants resulted in recombinantstaphylococci with increased metal-binding capacity compared tocontrol strains, indicating that this could become a generalstrategy to engineer bacteria for improved binding to specificmetal ions. Directed immobilization of cells with surface displayedheterologous proteins have widespread use in modernbiotechnology. Among other things they could provide aconvenient way of generating biofilters, biocatalysts orwhole-cell diagnostic devices. It was therefore investigatedwhether directed immobilization of recombinant staphylococci oncotton fibers could be achieved by functional display of afungal cellulose-binding domain (CBD). Recombinant S. carnosuscells with surface anchored CBDs from Trichoderma reseii Cel6Awere found to efficiently bind to cotton fibers creating almosta monolayer on the fibrous support. The co-expression of thisCBD together with previously described metal-binding proteinson the surface of our staphylococci would create means fordeveloping effective bioadsorbents for remediationpurposes. The original plasmid vector, designed for heterologoussurface display on recombinant S. carnosus cells has exhibitedproblems related to structural instability, possibly due to thepresence of a phage f1 origin of replication in the vectorsequence. This would be a problem if using the vector systemfor library display applications. Therefore, novel surfacedisplay vectors, lacking the phage ori were constructed andevaluated by enzymatic and flow cytometric whole-cell assays.One such novel vector, pSCXm, exhibited dramatically increasedplasmid stability with the retained high surface density ofexpressed heterologous proteins characteristic for the originalS. carnosus display vector, thus making it potentially moresuitable for library display applications. The successful engineering of our staphylococcal displaysystem encouraged us to further evaluate the potential to usethe staphylococcal system for display of combinatorial proteinlibraries and subsequent affinity based selections using flowcytometric cell sorting. A model system of recombinant S.carnosus cells with surface displayed engineered protein Adomains was constructed. It was demonstrated that target cellscould be sorted essentially quantitatively from a moderateexcess of background cells in a single sorting-step.Furthermore, the possibility of using staphylococcal surfacedisplay and flow cytometric cell sorting also for specificenrichment of very rare target cells by multiple rounds ofcell-sorting and in between amplification was demonstrated. <b>Key words:</b>affibody, albumin binding protein, bacterialsurface display, cell immobilization, bioremediation,combinatorial protein engineering, flow cytometry,Gram-positive, metal binding, staphylococcal protein A,Staphylococcus carnosus, Staphylococcus xylosus, whole-celldevices

<p>The engineering of bacterial surfaces has in recent yearsattracted a lot of attention with applications in manydifferent areas of bioscience. Here we describe the use of twodifferent surface display systems for the gram-positivebacteria Staphylococcus carnosus and Staphylococcus xylosus invarious biotechnological applications.</p><p>Environmental microbiology currently attracts a lot ofattention since genetically engineered plants and bacteriamight be used as bioadsorbents for sequestration of toxicmetals. Bacterial surface display of metal-binding peptidesmight enable recycling of the biomass by desorption ofaccumulated heavymetals. In an attempt to recruitstaphylococcal display systems for bioremediation purposes,polyhistidyl peptides were successfullly displayed on thesurface of recombinant S. carnosus and S. xylosus cells.Whole-cell Ni2+-binding assays demonstrated that therecombinant cells had gained metal-binding capacity compared towild-type cells.</p><p>Tailor-made, metal-binding staphylococci was created using apreviously constructed phage-display combinatorial proteinlibrary based on a fungal cellulose-binding domain (CBD)derived from the cellobiohydrolase Cel7A of Trichoderma reseii.Novel metal-binding CBDs were generated through a phagemediated selection procedure. Selected CBD variants, now devoidof cellulose binding, were randomly selected and sequenceanalysis of selected variants revealed a marked preference forhistidine residues at the randomized positions. Surface displayof these novel CBD variants resulted in recombinantstaphylococci with increased metal-binding capacity compared tocontrol strains, indicating that this could become a generalstrategy to engineer bacteria for improved binding to specificmetal ions.</p><p>Directed immobilization of cells with surface displayedheterologous proteins have widespread use in modernbiotechnology. Among other things they could provide aconvenient way of generating biofilters, biocatalysts orwhole-cell diagnostic devices. It was therefore investigatedwhether directed immobilization of recombinant staphylococci oncotton fibers could be achieved by functional display of afungal cellulose-binding domain (CBD). Recombinant S. carnosuscells with surface anchored CBDs from Trichoderma reseii Cel6Awere found to efficiently bind to cotton fibers creating almosta monolayer on the fibrous support. The co-expression of thisCBD together with previously described metal-binding proteinson the surface of our staphylococci would create means fordeveloping effective bioadsorbents for remediationpurposes.</p><p>The original plasmid vector, designed for heterologoussurface display on recombinant S. carnosus cells has exhibitedproblems related to structural instability, possibly due to thepresence of a phage f1 origin of replication in the vectorsequence. This would be a problem if using the vector systemfor library display applications. Therefore, novel surfacedisplay vectors, lacking the phage ori were constructed andevaluated by enzymatic and flow cytometric whole-cell assays.One such novel vector, pSCXm, exhibited dramatically increasedplasmid stability with the retained high surface density ofexpressed heterologous proteins characteristic for the originalS. carnosus display vector, thus making it potentially moresuitable for library display applications.</p><p>The successful engineering of our staphylococcal displaysystem encouraged us to further evaluate the potential to usethe staphylococcal system for display of combinatorial proteinlibraries and subsequent affinity based selections using flowcytometric cell sorting. A model system of recombinant S.carnosus cells with surface displayed engineered protein Adomains was constructed. It was demonstrated that target cellscould be sorted essentially quantitatively from a moderateexcess of background cells in a single sorting-step.Furthermore, the possibility of using staphylococcal surfacedisplay and flow cytometric cell sorting also for specificenrichment of very rare target cells by multiple rounds ofcell-sorting and in between amplification was demonstrated.</p><p><b>Key words:</b>affibody, albumin binding protein, bacterialsurface display, cell immobilization, bioremediation,combinatorial protein engineering, flow cytometry,Gram-positive, metal binding, staphylococcal protein A,Staphylococcus carnosus, Staphylococcus xylosus, whole-celldevices</p>