京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19041号 / 農博第2119号 / 新制||農||1032(附属図書館) / 学位論文||H27||N4923(農学部図書室) / 31992 / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 植田 充美, 教授 渡邊 隆司, 教授 梅澤 俊明 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

A contributing factor in recurrent Listeria monocytogenes (L. monocytogenes) food contamination is that this bacterium produces biofilms on surfaces to persist in food-processing environments. Quorum sensing (QS) is a cell-to-cell communication system utilized by bacteria within biofilms to collaborate and adapt to environmental stresses. However, the details of how the QS-dependent network contributes to biofilm development of L. monocytogenes have yet to be well understood. By comparing the transfer rates of planktonic and biofilm (sessile) L. monocytogenes from stainless steel blades to bologna slices, we found that sessile bacteria had reduced transferability onto a single slice but caused the increase in the number of contaminated slices. This suggests that physiological adaptions derived during biofilm development affect bacterial dissemination. Given the contribution of proteins and environmental temperatures to the extracellular polymeric substances (EPS) synthesis and biofilm integrity, we evaluated the exoproteomes of biofilms formed at 25 and 37°C using 2D-gel electrophoresis and LC-MS/MS. We found exoproteases Lmo0186, Cwh, and Spl exclusively in biofilms formed at 25°C and their greater expression in the gene level at 25°C. By using the zymography and crystal-violet-staining assay with a protease inhibitor, we observed a greater proteolytic activity at lower temperatures and showed that the attenuated proteolytic activity of proteases is positively correlated with increased biofilmorming ability at 25°C. Considering the transcriptional role of QS systems during biofilm development, we investigated how the accessory gene regulator (Agr)-based and metabolite S-Adenosylmethionine (SAM)-involved QS systems modulate nutrient availability and EPS synthesis. The results revealed that the SAM signal interacts with the Agr QS at the transcriptional level during biofilm development, whereas SAM and Agr QS regulate distinct EPS synthesis pathways. Additionally, this interaction is dependent on bacterial life modes (planktonic and sessile). Overall, we conclude that L. monocytogenes manipulates the synthesis of EPS with the coregulation of metabolism and QS for biofilm formation and the production of exoproteases for biofilm dispersion. These precise regulations on EPS enable L. monocytogenes to prolong its survival and promote its dissemination in environments.

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-12-10T14:10:12Z No. of bitstreams: 2 Dissertação - Lucas Silva de Oliveira - 2014.pdf: 3199133 bytes, checksum: cb42a7815c2701477249ff4d0cb2a05b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-12-11T07:57:23Z (GMT) No. of bitstreams: 2 Dissertação - Lucas Silva de Oliveira - 2014.pdf: 3199133 bytes, checksum: cb42a7815c2701477249ff4d0cb2a05b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2015-12-11T07:57:23Z (GMT). No. of bitstreams: 2 Dissertação - Lucas Silva de Oliveira - 2014.pdf: 3199133 bytes, checksum: cb42a7815c2701477249ff4d0cb2a05b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-04-23 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Staphylococcus saprophyticus is characterized as uropathogenic bacteria that causes urinary tract infections especially in young women. Some virulence factors were elucidated, however, little is known about how this bacteria install itself at host human. The urease was the first virulence factor described in S. saprophyticus, being responsible by increasing of the bladder pH in infected patients. This is the first study about S. saprophyticus in proteomics and immunoproteomics perspective of the secreted proteins (exoproteome) of this bacterium. A total of 44 new secreted proteins were detected by mass spectrometry. Among the proteins found, five of them have a crucial role in the glycolytic pathway: Triosephosphate isomerase (TPI), enolase (ENO), Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and Glucose-6-phosphate isomerase (GPI), however, its role as moonlighting proteins have been observed in various microorganisms. Through of the immunoproteomics, it was possible to detect 18 protein species that reacted onto Western-blotting, and 5 of them could be identified by mass spectrometry. The most abundant protein specie identified as immunogenic in S. saprophyticus, it was transglycosilase IsaA (Immunodominant staphylococcal antigen A), being it well described in Staphylococcus aureus as virulence factor. Another abundant protein found as immunogenic was Ssa (Staphylococcal secretory antigen), which, it was identified under 3 isoforms. The enolase was the last protein identified at immunoproteome of S. saprophyticus. It was possible to conclude from these results that S. saprophyticus has a wide of extracellular proteins capable to promote bacteria adaption, and some of them are involved in oxidative/nitrosative stress (SOD and AhpC), besides possess proteins that have the capacity to incite the humoral immune response in BalbC mice. All this lead us to hypothesize that S. saprophyticus have defense and virulence mechanisms in order to protect itself against extracellular stresses and appropriate mechanisms to promote urinary tract infections. / Staphylococcus saprophyticus caracteriza-se por ser uma bactéria uropatogênica que causa infecção no trato genito-urinário especialmente de mulheres jovens. Alguns fatores de virulência já foram elucidados, no entanto, pouco se conhece do modo pelo qual esta bactéria acomete o hospedeiro humano. A uréase foi o primeiro fator de virulência descrito em S. saprophyticus, sendo responsável pela alcalinização do pH da bexiga de pacientes contaminados. Este estudo é o pioneiro tratando-se de S. saprophyticus na abordagem da proteômica e imunoproteômica do perfil de proteínas secretadas (exoproteoma) por esta bactéria. Um total de 44 proteínas secretadas inéditas foram detectadas por espectrometria de massas. Dentre as proteínas encontradas, cinco delas possuem papel fundamental na via glicolítica: triose-fosfato isomerase (TPI), enolase (ENO), gliceraldeído-3-fosfato-desidrogenase (GAPDH) e glicose-6-fosfato isomerase (GPI), no entanto, seu papel como proteína “moonlighting” já foi observado em diversos microrganismos. Através da imunoproteômica, foi possível detectar 18 espécies proteicas que reagiram no Wester-blotting, e 5 delas puderam ser identificadas por espectrometria de massas. A espécie proteica mais abundante identificada como imunogênica em S. saprophyticus, foi a transglicosilase IsaA (Immunodominant staphylococcal antigen A), sendo bem descrita em S. aureus como um fator de virulência. Outra proteína abundante identificada como imunogênica foi a Ssa (Staphylococcal secretory antigen), no qual, foi identificada em 3 isoformas. A enolase também foi identificada no imunoproteoma de S. saprophyticus. Foi possível concluir através destes resultados que S. saprophyticus possui uma gama de proteínas extracelulares capazes de promover a adaptação desta bactéria, algumas delas envolvidas na proteção contra o estresse oxidativo/nitrosativo (SOD e AhpC), além de possuir proteínas que tem a característica de incitar a resposta imune humoral de camundongos BalbC. Isso tudo nos leva a hipotetizar que S. saprophyticus possui mecanismos de defesa e virulência a fim de se proteger contra estresses exteriores e mecanismos para promover a patogênese no trato genito-urinário.

Listeria monocytogenes est une bactérie pathogène impliquée dans la toxi-infection alimentaire à l’origine de la listeriose, une maladie peu fréquente mais avec un taux de mortalité de 25 % chez l’homme. Cette bactérie est capable de former un biofilm lui permettant de mieux résister aux stress environnementaux ainsi qu’aux traitements de décontamination. Une nouvelle stratégie d’analyse génomique a été développée et a permis de cibler des systèmes de sécrétion et des protéines potentiellement impliqués dans la formation de biofilm. L’inactivation de la voie SecA2 entraîne la formation d’un biofilm aérien et par conséquent fragile. Ce morphotype est capable de croître de façon sessile à 20°C sur du polystyrène alors que ce n’est pas le cas pour la souche sauvage. De nouvelles protéines sécrétées de façon SecA2 dépendante ont été identifiées par l’étude de l’exoprotéome du mutant ΔsecA2 en comparaison avec celui de la souche sauvage. Le rôle des lipoprotéines dans la formation de biofilm ainsi que leur maturation par les peptidases signal de type II, LspA et LspB, a également été abordé. La combinaison d'une analyse de l’expression des gènes codant les lipoprotéines au cours de la formation de biofilm avec l’analyse génomique basé sur le sécrétome a permis de cibler trois lipoprotéines, dont LpeA qui serait impliquée dans les phases tardives de formation de biofilm. Enfin, l’importance majeure de LspA dans la maturation des lipoprotéines, a été mise en évidence par l’étude de l’exoprotéome des doubles mutant ΔlgtΔlspA et ΔlgtΔlspB en comparaison avec celui de Δlgt. / Listeria monocytogenes is a foodborne pathogenic bacteria responsible for listeriosis, a rare but high mortality rate disease in humans (25 %). This bacterium can form biofilm allowing a better resistance to environmental stresses as well as decontamination treatments. A new strategy for genomic analysis was developed and allowed to target secretion systems and proteins potentially involved in biofilm formation. Inactivation of the SecA2 pathway leads to the formation of an aerial and fragile biofilm. This morphotype is able to grow in a sessile mode at 20 °C on polystyrene whereas this is not the case for the wild type strain. New proteins secreted in a SecA2 manner were identified by comparing the ΔsecA2 exoproteome to the one of the wild type. The role of lipoproteins in biofilm formation and their maturation by the signal peptidase II, LpsA and LspB, was also tackled. Combining expression analysis of genes encoding lipoproteins during biofilm formation with genomic analysis based on the secretome allowed targeting three lipoproteins, including LpeA, which appeared to be involved in the later stages of biofilm formation. Finally, the importance of LspA in the maturation of lipoproteins,was highlighted by comparing of the double mutant ΔlgtΔlspA and ΔlgtΔlspB exoproteomes to the one of Δlgt.