The three-dimensional structure of CFA/I adhesion pili: Traveler's diarrhea bacteria hang on by a spring

JOURNAL OF MOLECULAR BIOLOGY

卷:376

Article

Mu, Xuang-Qi¹  Savarino, Stephen J.²  Bullitt, Esther¹ 

[1] Boston Univ, Sch Med, Dept Physiol & Biophys, Boston, MA 02118 USA

[2] USN, Med Res Ctr, Enter Dis Dept, Silver Spring, MD 20910 USA

关键词: adhesion pili;    fimbriae;    ETEC;    helical reconstruction;    electron microscopy and image processing;   

DOI  :  10.1016/j.jmb.2007.10.067

来源: Elsevier

【 摘 要 】

To survive the harsh environment of a churning intestinal tract, bacteria attach to the host epithelium via thin fibers called pili (or fimbriae). Enterotoxigenic Escherichia coli bacteria expressing colonization factor antigen I (CFA/I) pili and related pili are the most common known bacterial cause of diarrheal disease, including traveler's diarrhea. CFA/I pili, assembled via the alternate chaperone pathway, are essential for binding and colonization of the small bowel by these pathogenic bacteria. Herein, we elucidate unique structural features of CFA/I pili that appear to optimize their function as bacterial tethers in the intestinal tract. Using transmission electron microscopy of negatively stained samples in combination with iterative three-dimensional helical reconstruction methods for image processing, we determined the structure of the CFA/I pilus filament. Our results indicate that strong end-to-end protein interactions and weak interactions between the coils of a sturdy spring-like helix provide the combination of strength, stability, and flexibility required to sustain bacterial adhesion and incite intestinal disease. We propose that CFA/I pili behave like a spring to maintain attachment to the gut lining during vortex mixing and downward flow of the intestinal contents, thereby persisting long enough for these bacteria to colonize the host epithelium and cause enteric disease. (C) 2007 Elsevier Ltd. All rights reserved.

【 授权许可】

Free