Substrate secretion by different EHEC secretion systems during their interaction with epithelial cells

Area of Science:

• Microbiology
• Pathogenesis
• Bacterial Secretion Systems

Background:

• Enterohemorrhagic Escherichia coli (EHEC) is a significant cause of human foodborne illness.
• EHEC possesses five types of secretion systems (SSs), but their collective role in host-pathogen interaction is poorly understood.
• While some substrates for these SSs are known, their coordinated function during infection remains largely unexplored.

Purpose of the Study:

• To investigate the collective function of EHEC secretion systems during interaction with epithelial cells.
• To elucidate the hierarchy and interdependence of protein secretion via different SSs in EHEC.
• To identify novel substrates secreted by EHEC SSs and understand their role in pathogenesis.

Main Methods:

• Optimized protein secretion assays for four EHEC SSs in vitro and in the presence of epithelial cells.
• Utilized Western blot and proteomics to analyze EHEC secretome changes.
• Performed bioinformatics analyses to predict new SS substrates.
• Generated and analyzed mutants deficient in specific SSs.

Main Results:

• Epithelial cells significantly increased protein secretion by EHEC, influencing the abundance of specific substrates.
• A hierarchical secretion pattern was observed when EHEC encountered epithelial cells.
• Mutations in one SS impacted the protein secretion of other SSs, indicating interdependence.
• Epithelial cells modulated the effects of SS mutations, and new potential substrates were identified.

Conclusions:

• A complex interplay exists between EHEC secretion systems during epithelial cell infection.
• This SS interaction influences host-pathogen interactions and EHEC pathogenesis.
• Understanding these SSs is crucial for developing strategies against EHEC infections.