The Longus type IV pilus of enterotoxigenic Escherichia coli (ETEC) mediates bacterial self-aggregation and protection from antimicrobial agents

• Published in: Microbial pathogenesis Vol. 48; no. 6; pp. 230 - 238
• Main Authors: Clavijo, Andrea P., Bai, Jing, Gómez-Duarte, Oscar G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier India Pvt Ltd 01-06-2010; Elsevier
• Subjects: Amino Acid Sequence; Anti-Bacterial Agents - pharmacology; Bacterial Adhesion; Bacteriology; Biological and medical sciences; Diarrhea; DNA, Bacterial - genetics; Enterotoxigenic E. coli; Enterotoxigenic Escherichia coli - drug effects; Enterotoxigenic Escherichia coli - genetics; Enterotoxigenic Escherichia coli - growth & development; Escherichia coli; Fimbriae, Bacterial - genetics; Fimbriae, Bacterial - metabolism; Fundamental and applied biological sciences. Psychology; Longus; Microbial Viability; Microbiology; Microscopy, Electron, Transmission; Miscellaneous; Molecular Sequence Data; Muramidase - pharmacology; Mutagenesis; Mutagenesis, Site-Directed; Mutation; Pili; Protein Structure, Secondary; Protein Structure, Tertiary; Vibrio cholerae; Diarrhea; Longus; Enterotoxigenic E. coli; Pili; Mutagenesis; Escherichia coli; Pilus; Antimicrobial agent; Aggregation; Bacteria; Digestive diseases; Intestinal disease; Enterobacteriaceae
• ISSN: 0882-4010; 1096-1208
• DOI: 10.1016/j.micpath.2010.03.006

Enterotoxigenic
Escherichia coli (ETEC) strains are leading causes of childhood diarrhea in developing countries. ETEC pili and non-pili adherence factors designated colonization surface antigens (CSA) are believed to be important in the pathogenesis of diarrhea. Longus, a type IV pilus identified as the CSA
21, is expressed in up to one-third of ETEC strains, and share similarities to the toxin-coregulated pilus of
Vibrio cholerae, and the bundle-forming pilus of enteropathogenic
E. coli. To identify longus phenotype and possible function, a site-directed mutation of the
lngA major subunit gene in the E9034A wild type ETEC strain was constructed. Lack of longus expression from the
lngA mutant was demonstrated by immunoblot analysis and electron microscopy using specific anti-LngA antibody. Formation of self-aggregates by ETEC was shown to be dependent on longus expression as the
lngA mutant or wild type grown under poor longus expression conditions was unable to express this phenotype. Longus-expressing ETEC were also associated with improved survival when exposed to antibacterial factors including lysozyme and antibiotics. This suggests that longus-mediated bacterial self-aggregates protect bacteria against antimicrobial environmental agents and may promote gut colonization.