BfpI, BfpJ, and BfpK Minor Pilins Are Important for the Function and Biogenesis of Bundle-Forming Pili Expressed by...

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Molecular Biology

Background:

• Enteropathogenic Escherichia coli (EPEC) causes significant infant diarrheal disease globally.
• EPEC colonizes the small intestine via a multistep process, starting with loose attachment mediated by bundle-forming pili (BFP).
• BFP are type 4b pili (T4bP) crucial for EPEC's host colonization strategy.

Purpose of the Study:

• To investigate the role of three minor pilin subunits (BfpI, BfpJ, BfpK) in BFP structure and function.
• To determine if these minor pilins are essential for BFP biogenesis and host cell adhesion.
• To explore the potential of these subunits as vaccine targets.

Main Methods:

• Genetic manipulation of EPEC strains to assess the necessity of BfpI, BfpJ, and BfpK for BFP formation.
• Biochemical analysis to confirm the incorporation of minor pilins into the BFP filament.
• Functional assays to evaluate the impact of minor pilins on bacterial adhesion to host cells.

Main Results:

• BfpI, BfpJ, and BfpK are dispensable for BFP biogenesis in the absence of the BFP retraction ATPase (BfpF).
• These minor pilins are incorporated into the BFP filament alongside the major subunit, bundlin.
• The presence of BfpI, BfpJ, and BfpK significantly contributes to the structural integrity and adhesive properties of BFP.

Conclusions:

• Minor pilins BfpI, BfpJ, and BfpK play a critical role in the structure and function of EPEC's bundle-forming pili.
• These findings extend knowledge of type 4b pilus systems, confirming observations from type 4a pili.
• The identified minor pilins represent potential targets for developing vaccines against EPEC infections.