The members of the genus Streptomyces are well-known for their capacity to synthesize a vast repertoire of secondary metabolites, including many useful antibiotics and proteins. Streptomyces clavuligerus is the producer of the medically important &amp / #946 / -lactam antibiotics such as cephamycin C and the potent &amp / #946 / -lactamase inhibitor clavulanic acid. The aspartate pathway of S. clavuligerus is an important primary metabolic pathway providing substrates for &amp / #946 / -lactam synthesis. This pathway uses L-aspartic acid as the precursor for the biosynthesis of the amino acids L-lysine, L-methionine, L-isoleucine, L-threonine and several important metabolic intermediates. L-&amp / #945 / -aminoadipic acid (&amp / #945 / -AAA) required for &amp / #946 / -lactam synthesis is a catabolic product of L-lysine produced from the lysine branch of the aspartate pathway. The carbon flow through the L-lysine-specific branch of aspartate pathway is limiting for the formation of cephamycin C. Formation of L-homoserine from aspartate semialdehyde (ASA) is the first step of the other branch of the aspartate pathway leading to L-threonine, L-isoleucine and L-methionine synthesis and is catalyzed by homoserine dehydrogenase (HSD, EC 1.1.1.3). Regulation of the activity or biosynthesis of the HSD of S. clavuligerus determines the availability of ASA for the biosynthesis of L-lysine and &amp / #945 / -AAA. The gene encoding for homoserine dehydrogenase (hom) was previously cloned from S. clavuligerus NRRL 3585 and characterized in our laboratory. In this study, the hom gene was disrupted via insertion of a kanamycin resistance cassette into this gene which was subsequently transferred to S. clavuligerus cells using the Streptomyces plasmid vector pIJ486. A hom mutant of S. clavuligerus (AK39) was formed through integration into the chromosome by double crossing over and the effects of hom disruption on cephamycin C yields were investigated. Disruption of hom gene resulted in a 1.7 to 2.0 fold increase in specific cephamycin C production in chemically defined medium (CDM).

Orientador: Anita Jocelyne Marsaioli / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-13T13:06:45Z (GMT). No. of bitstreams: 1 Pomini_ArmandoMateus_D.pdf: 4501241 bytes, checksum: 249f7514962993874b22ddcad9831cc8 (MD5) Previous issue date: 2009 / As bactérias Gram-positivas e Gram-negativas possuem um mecanismo de comunicação química intra-específico conhecido como ¿quorum-sensing¿, regulando a expressão de uma vasta gama de atividades biológicas. As bactérias Gram-negativas utilizam acil-homosserina lactonas (acil-HSLs) como principais substâncias sinalizadoras. Na presente tese, relatamos a determinação da configuração absoluta do raro metabólito (S)-(-)-N-heptanoil-HSL produzida pela bactéria fitopatogênica Pantoea ananatis. A configuração absoluta desta substância foi determinada através da técnica de cromatografia gasosa com detecção por ionização em chama com coluna quiral, através de comparações de tempo de retenção e co-injeção com padrões sintetizados. Avaliou-se também a importância da configuração absoluta para a atividade antimicrobiana de acil-HSLs contra bactérias Gram-positivas (Bacillus subtilis, Bacillus cereus e Staphylococcus aureus). Curiosamente, o enantiômero não natural (R)-N-3-oxo-octanoil-HSL foi tão ativo quanto o produto natural (S). Estudou-se também as interações da (S)-N-3-oxo-octanoil-HSL com células de Agrobacterium tumefaciens NTL4(pZLR4) através da técnica de ressonância magnética nuclear de hidrogênio por diferença de transferência de saturação (STD-RMN), revelando que o primeiro evento de interação da substância com a célula ocorre com a região lipídica da membrana celular externa. Finalmente, realizou-se o estudo químico das substâncias sinalizadoras produzidas pela bactéria Methylobacterium mesophilicum, que ocorre simbioticamente com a bactéria Xylella fastidiosa nos vasos condutores de laranjeiras atacadas pela clorose variegada dos citros. Entre os vários resultados inéditos, reportamos a caracterização e síntese do produto natural inédito (S)-N-(2E)-dodecenoil-HSL e a primeira síntese do metabólito (S)-N-(2E, 7Z)-tetradecadienil-HSL. Outrossim, reportamos a primeira caracterização da configuração absoluta de cinco acil-HSLs naturais de cadeia longa. Realizou-se também estudos relacionados aos efeitos das acil-HSLs sintéticas contra bactérias Gram-positivas endofíticas da laranjeira. Adicionalmente, caracterizou-se a secreção de defesa do opilião Hoplobunus mexicanus. O repertório de defesa deste animal é composto por dois componentes voláteis de alta irritabilidade (2,5-dimetil-fenol e 2-metil-5-etil-fenol), além da tanatose e emissão de sons, uma característica inédita em opiliões / Gram-positive and Gram-negative bacteria use quorum sensing communication circuits to regulate a diverse array of physiological activities. In general, Gram-negative bacteria use acylated homoserine lactones (acyl-HSLs) as autoinducers, and Gram-positive bacteria use processed oligo-peptides. In the present work, we relate the absolute configuration determination of the rare metabolite (S)-(-)-N-heptanoyl-HSL produced by the phytopathogen Pantoea ananatis. The absolute configuration was determined by gas chromatography coupled to flame ionization detection with chiral column, through retention time comparison and co-injections with synthetic products. The importance of the absolute configuration for the antimicrobial activity of acyl-HSL against Gram-positive bacteria (Bacillus subtilis, Bacillus cereus and Staphylococcus aureus) was assessed. Curiously, non-natural (R)-N-3-oxo-octanoyl-HSL was as active as the natural product with (S) absolute configuration. The interaction of (S)-N-3-oxo-octanoil-HSL with Agrobacterium tumefaciens NTL4(pZLR4) cells was further studied using hydrogen nuclear magnetic resonance experiments with saturation transfer difference (STD-NMR) revealing that the first binding event is the diffusion through the lipidic part of the outer membrane. Finally, we have investigated the chemical study of the signaling substances produced by Methylobacterium mesophilicum, which co-occurs with Xylella fastidiosa in orange trees affected by the citrus variegated chlorosis disease. Among several results, we report herein the characterization and synthesis of a new natural product [(S)-N-(2E)-dodecenoyl-HSL], the first synthetic procedure for the rare (S)-N-(2E,7Z)-tetradecadienyl-HSL and the occurrence of a rare long, odd chain representative (N-tridecanoyl-HSL) in trace amounts. We report the first absolute configuration determination for five natural acyl-HSLs. We have also studied the effects of synthetic acyl-HSLs on Gram positive bacteria isolated from orange tissues. Additionally, the defensive secretion produced by the harvestman Hoplobunus mexicanus was characterized. The defensive repertory of this arachnid includes two irritating and volatile components (2,5-dimethyl-phenol and 2-methyl-5-ethyl-phenol), besides thanatosis and sound emission, a new behavioral artifice in opilionids / Doutorado / Quimica Organica / Doutor em Ciências

A semente de milho, base da alimentação em muitos países na África, Ásia e América Latina, possui ~10% de proteína na semente. Por ser um cereal a proteína da semente de milho apresenta uma baixa concentração de aminoácidos essenciais como: lisina e triptofano. Com a descoberta do milho opaco-2, o qual apresenta um maior teor de lisina e triptofano em suas sementes, surgiu a oportunidade de se desenvolver milhos com qualidade protéica, aumentando o conteúdo de aminoácidos e a qualidade nutricional dos grãos. Assim, surgiu o milho QPM (quality protein maize), milho de alta qualidade protéica, melhorado pelo CIMMYT (México). O QPM possui duas vezes mais lisina que o milho normal mantendo a sua produtividade equivalente. A EMBRAPA, Milho e Sorgo, desenvolveu duas variedades QPM comercializadas: BR451 e BR473. A linhagem QPM 161 (EMBRAPA Milho e Sorgo) teve suas proteínas de reserva analisadas bioquimicamente neste trabalho, concluindo que o QPM 161, possui uma concentração maior de lisina em suas sementes, chegando a superar o BR 451 e a manter a mesma concentração de lisina que o BR 473. Em outra parte do trabalho, sementes imaturas (14, 20 e 14 DAP) das linhagens 161, assim como as do selvagem W22+ e de seus mutantes W22o10, W22o11 e W22o13, foram utilizadas para caracterizar a enzima homoserina quinase (HK). A HK faz parte da via de biossíntese do aminoácido essencial treonina. Constatou-se que uma alta atividade desta enzima está relacionada ao aumento de treonina na semente, porém, a alta atividade de HK foi observada nos menores estágios de maturação. Assim os resultados mostram que mais estudos sobre a regulação desta enzima devem ser realizados para que se possam desenvolver sementes ricas em lisina e também em treonina. / Maize which is the staple food in many countries in Africa, Asia and Latin America, has ~10% of protein in the seeds. Maize seeds protein presents low contents of essential amino acids, such as lysine and tryptophan. Since the discovery of the opaque-2 maize, a recessive mutation that results in high concentrations of lysine and tryptophan, the major challenge has been to develop better quality protein maize to increase the rate of amino acids consumed by population. The QPM (quality protein maize), originally produced and breeded at CIMMYT in Mexico, came to solve the issue. The QPM protein has twice as much lysine and tryptophan, with the same yield of normal maize. The EMBRAPA, Maize and Sorghum, has bred two QPM varieties that are already commercialized (BR 451 and BR 473), but to increase the quality of the Brazilian QPM, EMBRAPA developed a new QPM line, the 161, whose storage proteins were biochemically analyzed in this study. Line 161 exhibited a higher lysine concentration than BR 451, but about the same concentration of that exhibited by BR 473. Further analyses conducted in this research involved the study of immature seeds (14, 20 and 24 DAP) of line 161, and the wild-type W22+ and its counterpart mutants W22o10, W22o11 and W22o13, and the characterization of the enzyme homoserine kinase (HK). HK is a key enzyme of the threonine biosynthetic pathway. The high HK activity was shown to be related to the increased threonine concentration in the maize seeds. HK activity was shown to reach the highest level in the first developmental stage, whereas in the last developmental stage the activity is lower and so is the rate of threonine. Therefore, it is necessary more studies on HK regulation to improve the mature maize seeds with the best rate of lysine and threonine.

Codakia orbicularis est un mollusque bivalve appartenant à la famille des Lucinidae et établissant des symbioses avec des bactéries sulfo-oxydantes (symbiotes) au sein de ses branchies. Dans l’hypothèse où toute symbiose nécessite une régulation par des molécules de dialogue, une étude chimique exhaustive pourrait aboutir à la mise en évidence des métabolites impliqués. Le travail de ce manuscrit porte donc sur l'isolement de métabolites secondaires à partir des branchies de ce bivalve et sur l'évaluation de l'activité antibactérienne des molécules isolées. Douze composés ont été isolés des branchies de Codakia orbicularis et leurs structures ont été déterminées par les méthodes spectroscopiques usuelles. Parmi ces molécules, une seule est nouvelle et a été nommée orbicularisine. Elle présente un squelette indolone spirotetracyclique inédit. Parmi les molécules isolées, seules quatre d’entre elles présentent une activité antibactérienne à savoir le soufre S8, la 4-hydroxybenzaldéhyde et deux monoglycérolipides. L'orbicularisine s'est révélée inactive contre un panel de lignées cellulaires cancéreuses et de kinases. Le nouveau squelette de l’orbicularisine pourrait permettre d'aboutir à une nouvelle famille de molécules par synthèse organique et ainsi accroître la diversité moléculaire autour de ce motif inédit. Il sera également intéressant de déterminer l'origine des molécules isolées et de connaître leur(s) implication(s) dans la régulation des symbiotes du bivalve. Les résultats chimiques obtenus sur C. orbicularis et sur les Lucinidae en général sont intéressants puisque les espèces côtières appartenant aux bivalves ont été peu exploitées en chimie jusqu’à ce jour. / Codakia orbicularis is a bivalve mollusc belonging to the family Lucinidae and establishing symbiosis with sulfooxidizing bacteria (symbionts) within its gills. In the hypothesis that any symbiosis requires a regulation by molecules of dialogue, an exhaustive chemical study could lead to the demonstration of the metabolites involved. The work of this manuscript focuses on the isolation of secondary metabolites from the gills of this bivalve and on the evaluation of the antibacterial activity of the isolated molecules. Twelve compounds were isolated from the gills of Codakia orbicularis and their structures were determined by the usual spectroscopic methods. Of these molecules, only one is new and has been named orbicularisin. It presents an indolone spirotetracyclic skeleton unpublished. Among the isolated molecules, only four of them have antibacterial activity, namely sulfur S8, 4-hydroxybenzaldehyde and two monoglycerolipids. Orbicularisin has been shown to be inactive against a panel of cancer cell lines and kinases. The new skeleton of orbicularisin could lead to a new family of molecules by organic synthesis and thus increase the molecular diversity around this original motif. It will also be interesting to determine the origin of the isolated molecules and know their involvement (s) in the regulation of the bivalve symbionts. The chemical results obtained on C. orbicularis and on Lucinidae in general are interesting because the coastal species belonging to bivalves have been little exploited in chemistry to date.

The black band disease (BBD) microbial consortium often causes mortality of reef-building corals. Microbial chemical interactions (i.e., quorum sensing (QS) and antimicrobial production) may be involved in the BBD disease process. Culture filtrates (CFs) from over 150 bacterial isolates from BBD and the surface mucopolysaccharide layer (SML) of healthy and diseased corals were screened for acyl homoserine lactone (AHL) and Autoinducer-2 (AI-2) QS signals using bacterial reporter strains. AHLs were detected in all BBD mat samples and nine CFs. More than half of the CFs (~55%) tested positive for AI-2. Approximately 27% of growth challenges conducted among 19 isolates showed significant growth inhibition. These findings demonstrate that QS is actively occurring within the BBD microbial mat and that culturable bacteria from BBD and the coral SML are able to produce QS signals and antimicrobial compounds. This is the first study to identify AHL production in association with active coral disease.

The tumor microenvironment is a well-recognized contributor to cancer progression in solid tumors. Cancer cell interactions with abnormal extracellular matrix, tumor associated immune and stromal cells, and aberrant fluid flow all contribute to cancer progression. Breast tumors are often characterized by a dense collagenous stroma and a hypoxic core. A recently identified and little understood component of the breast tumor microenvironment is the breast microbiome. The work described here elaborates on the importance of the tumor microenvironment in cancer progression and demonstrates the importance of studying cancer-microbiome interactions in the context of tumor microenvironmental stimuli. / Master of Science / One of the major barriers to effective cancer treatment is the environment is which cancer grows. Tumors insulate themselves in a thick protein structure that leads to a stiffening of the breast tissue. In addition, irregular tumor-associated blood vessels lead to poor blood flow, and therefore a lack of oxygen, in the center of the tumor. These and other characteristics of tumors create an environment in which cancer cells are resistant to current anti-cancer therapies and thereby allows them to flourish. It was recently discovered that, contrary to previous belief, there are resident bacteria present in normal and cancerous breast tissue. The role they play in controlling cancer development and progression in the tumor is unknown. The work described here elaborates on the tumor environmental barriers to current anti-cancer therapies and shows how one bacterial produced compound may interact with other features of the tumor environment in order to control breast cancer survival.

Yes / Bacterial cells sense their population density and respond accordingly by producing various signal molecules to the surrounding environments thereby trigger a plethora of gene expression. This regulatory pathway is termed quorum sensing (QS). Plenty of bacterial virulence factors are controlled by QS or QS-mediated regulatory systems and QS signal molecules (QSSMs) play crucial roles in bacterial signaling transduction. Moreover, bacterial QSSMs were shown to interfere with host cell signaling and modulate host immune responses. QSSMs not only regulate the expression of bacterial virulence factors but themselves act in the modulation of host biology that can be potential therapeutic targets. / Open Access Funding from the University of Dundee.Also supported by the University of Malaya High Impact Research Grants (UMC/625/1/HIR/MOHE/CHAN/01,A-000001-50001,and UM C/625/1/HIR/MOHE/CHAN/14/1, H-50001-A000027)

Yes / Bacteria sense their own population size, tune the expression of responding genes, and behave accordingly to environmental stimuli by secreting signaling molecules. This phenomenon is termed as quorum sensing (QS). By exogenously manipulating the signal transduction bacterial population behaviors could be controlled, which may be done through quorum quenching (QQ). QS related regulatory networks have been proven their involvement in regulating many virulence determinants in pathogenic bacteria in the course of infections. Interfering with QS signaling system could be a novel strategy against bacterial infections and therefore requires more understanding of their fundamental mechanisms. Here we review the development of studies specifically on the inhibition of production of N-acyl-homoserine lactone (AHL), a common proteobacterial QS signal. The opportunistic pathogen, Pseudomonas aeruginosa, equips the alkylquinolone (AQ)-mediated QS which also plays crucial roles in its pathogenicity. The studies in QQ targeting on AQ are also discussed. / University of Malaya High Impact Research Grants (UMC/625/1/HIR/MOHE/CHAN/01, A-000001-50001,and UMC/625/1/HIR/MOHE/CHAN/14/1, H-50001-A000027)

Yes / Burkholderia spp. rely on N-acyl homoserine lactone as quorum-sensing signal molecules which coordinate their phenotype at the population level. In this work, we present the whole genome of Burkholderia sp. strain A9, which enables the discovery of its N-acyl homoserine lactone synthase gene. / UM High Impact Research Grants (UM-MOHE HIR grant UM C/625/1/HIR/MOHE/CHAN/01, H-50001-A000001 and UMMOHE HIR Grant UM C/625/1/HIR/MOHE/CHAN/14/1, H-50001- A000027)

L'environnement marin est constitué d'écosystèmes nombreux et variés, qui sont habités par des organismes appartenant aux trois domaines du vivant dont celui des bactéries. La coopération bactérienne est basée sur un mécanisme moléculaire appelé quorum sensing (QS). Ce système est dépendant de la densité cellulaire de la communauté, ce qui permet aux bactéries de synchroniser leur expression génétique, pour coordonner certaines de leurs activités physiologiques. Les bactéries produisent plusieurs types de molécules signal dont les acyl-homosérines lactones (AHLs ou AI-1) et le furanosyl diester borate (AI-2). La majorité des recherches dans le domaine du QS s'est portée sur des modèles bactériens d'intérêt biomédical ou agronomique. Cependant, l'importance du QS chez les bactéries marines reste mal connu. Ce travail de thèse a pour question: Quelle est la prévalence des AI chez les bactéries marines ? Pour aborder cette problématique : trois axes : Le criblage de la collection de bactéries marines MOLA, qui est basé sur des techniques de chimie des substances naturelles, et a permis de mettre en exergue des souches bactériennes originales comme Maribius sp MOLA 401, qui produisent un très grand nombre d'AHLs avec de nouvelles structures. Le second axe s'appuie sur des méthodes de bio-informatique pour réaliser le criblage du métagénome marin du Global Ocean Sampling pour la recherche de gènes luxI, ainS, hdtS et luxS. L'ensemble de ces données sur la diversité, l'abondance et la répartition biogéographique des AI-1 dans l'écosystème marin suggère une forte importance des mécanismes du QS à l'¿uvre dans les communautés bactériennes marines naturelles. / The marine environment is composed of many and varied ecosystems, which are inhabited by organisms belonging to the three domains of life including the bacteria. Bacterial cooperation is based on a molecular mechanism called quorum sensing (QS). This system is dependent on the cell density of the community, which allows bacteria to synchronize their gene expression, to coordinate some of their physiological activities. Bacteria produce several types of signal molecules with acyl-homoserines lactones (AHLs or AI-1) and the furanosyl borate diester (AI-2). The majority of research in the field of QS has focused on bacterial models for biomedical and agricultural interest. However, the importance of QS in marine bacteria remains unclear. This work has the question: What is the prevalence of AI in marine bacteria? To address this problem two axes: Screening the collection of marine bacteria MOLA, which is based on chemistry techniques of natural substances, and allowed to highlight original bacterial strains as Maribius sp MOLA 401, which produce very large number of AHLs with new structures. The second axis is based on the methods of bioinformatics to perform screening of metagenome marine Global Ocean Sampling for research luxI, ainS, luxS and hdtS genes,. All these data on diversity, abundance and biogeographical distribution of AI-1 in the marine ecosystem suggests a strong importance of QS mechanisms at work in the natural marine bacterial communities.