Dataset Information

Transient shielding of intimin and the type III secretion system of enterohemorrhagic and enteropathogenic Escherichia coli by a group 4 capsule.

ABSTRACT: Enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC, respectively) strains represent a major global health problem. Their virulence is mediated by the concerted activity of an array of virulence factors including toxins, a type III protein secretion system (TTSS), pili, and others. We previously showed that EPEC O127 forms a group 4 capsule (G4C), and in this report we show that EHEC O157 also produces a G4C, whose assembly is dependent on the etp, etk, and wzy genes. We further show that at early time points postinfection, these G4Cs appear to mask surface structures including intimin and the TTSS. This masking inhibited the attachment of EPEC and EHEC to tissue-cultured epithelial cells, diminished their capacity to induce the formation of actin pedestals, and attenuated TTSS-mediated protein translocation into host cells. Importantly, we found that Ler, a positive regulator of intimin and TTSS genes, represses the expression of the capsule-related genes, including etp and etk. Thus, the expression of TTSS and G4C is conversely regulated and capsule production is diminished upon TTSS expression. Indeed, at later time points postinfection, the diminishing capsule no longer interferes with the activities of intimin and the TTSS. Notably, by using the rabbit infant model, we found that the EHEC G4C is required for efficient colonization of the rabbit large intestine. Taken together, our results suggest that temporal expression of the capsule, which is coordinated with that of the TTSS, is required for optimal EHEC colonization of the host intestine.

SUBMITTER: Shifrin Y

PROVIDER: S-EPMC2447026 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Transient shielding of intimin and the type III secretion system of enterohemorrhagic and enteropathogenic Escherichia coli by a group 4 capsule.

Shifrin Yulia Y Peleg Adi A Ilan Ophir O Nadler Chen C Kobi Simi S Baruch Kobi K Yerushalmi Gal G Berdichevsky Tatiana T Altuvia Shoshy S Elgrably-Weiss Maya M Abe Cecilia C Knutton Stuart S Sasakawa Chihiro C Ritchie Jennifer M JM Waldor Matthew K MK Rosenshine Ilan I

Journal of bacteriology 20080523 14

Enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC, respectively) strains represent a major global health problem. Their virulence is mediated by the concerted activity of an array of virulence factors including toxins, a type III protein secretion system (TTSS), pili, and others. We previously showed that EPEC O127 forms a group 4 capsule (G4C), and in this report we show that EHEC O157 also produces a G4C, whose assembly is dependent on the etp, etk, and wzy genes. We furth ...[more]

PMID: 18502854

Similar Datasets

Project description:UnlabelledTranslocation of effector proteins via a type III secretion system (T3SS) is a widespread infection strategy among Gram-negative bacterial pathogens. Each pathogen translocates a particular set of effectors that subvert cell signaling in a way that suits its particular infection cycle. However, as effector unbalance might lead to cytotoxicity, the pathogens must employ mechanisms that regulate the intracellular effector concentration. We present evidence that the effector EspZ controls T3SS effector translocation from enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli. Consistently, an EPEC espZ mutant is highly cytotoxic. Following ectopic expression, we found that EspZ inhibited the formation of actin pedestals as it blocked the translocation of Tir, as well as other effectors, including Map and EspF. Moreover, during infection EspZ inhibited effector translocation following superinfection. Importantly, while EspZ of EHEC O157:H7 had a universal "translocation stop" activity, EspZ of EPEC inhibited effector translocation from typical EPEC strains but not from EHEC O157:H7 or its progenitor, atypical EPEC O55:H7. We found that the N and C termini of EspZ, which contains two transmembrane domains, face the cytosolic leaflet of the plasma membrane at the site of bacterial attachment, while the extracellular loop of EspZ is responsible for its strain-specific activity. These results show that EPEC and EHEC acquired a sophisticated mechanism to regulate the effector translocation.ImportanceEnteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are important diarrheal pathogens responsible for significant morbidity and mortality in developing countries and the developed world, respectively. The virulence strategy of EPEC and EHEC revolves around a conserved type III secretion system (T3SS), which translocates bacterial proteins known as effectors directly into host cells. Previous studies have shown that when cells are infected in two waves with EPEC, the first wave inhibits effector translocation by the second wave in a T3SS-dependent manner, although the factor involved was not known. Importantly, we identified EspZ as the effector responsible for blocking protein translocation following a secondary EPEC infection. Interestingly, we found that while EspZ of EHEC can block protein translocation from both EPEC and EHEC strains, EPEC EspZ cannot block translocation from EHEC. These studies show that EPEC and EHEC employ a novel infection strategy to regulate T3SS translocation.

Project description:UnlabelledType III secretion systems (TTSSs) are employed by pathogens to translocate host cells with effector proteins, which are crucial for virulence. The dynamics of effector translocation, behavior of the translocating bacteria, translocation temporal order, and relative amounts of each of the translocated effectors are all poorly characterized. To address these issues, we developed a microscopy-based assay that tracks effector translocation. We used this assay alongside a previously described real-time population-based translocation assay, focusing mainly on enteropathogenic Escherichia coli (EPEC) and partly comparing it to Salmonella. We found that the two pathogens exhibit different translocation behaviors: in EPEC, a subpopulation that formed microcolonies carried out most of the translocation activity, while Salmonella executed protein translocation as planktonic bacteria. We also noted variability in host cell susceptibility, with some cells highly resistant to translocation. We next extended the study to determine the translocation dynamics of twenty EPEC effectors and found that all exhibited distinct levels of translocation efficiency. Further, we mapped the global effects of key TTSS-related components on TTSS activity. Our results provide a comprehensive description of the dynamics of the TTSS activity of EPEC and new insights into the mechanisms that control the dynamics.ImportanceEPEC and the closely related enterohemorrhagic Escherichia coli (EHEC) represent a global public health problem. New strategies to combat EPEC and EHEC infections are needed, and development of such strategies requires better understanding of their virulence machinery. The TTSS is a critical virulence mechanism employed by these pathogens, and by others, including Salmonella. In this study, we aimed at elucidating new aspects of TTSS function. The results obtained provide a comprehensive description of the dynamics of TTSS activity of EPEC and new insights into the mechanisms that control these changes. This knowledge sets the stage for further analysis of the system and may accelerate the development of new ways to treat EPEC and EHEC infections. Further, the newly described microscopy-based assay can be readily adapted to study the dynamics of TTSS activity in other pathogens.

Dataset Information

Transient shielding of intimin and the type III secretion system of enterohemorrhagic and enteropathogenic Escherichia coli by a group 4 capsule.

Publications

Transient shielding of intimin and the type III secretion system of enterohemorrhagic and enteropathogenic Escherichia coli by a group 4 capsule.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets