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Crystal structure of enterotoxigenic E scherichia coli colonization factor CS 6 reveals a novel type of functional assembly
Author(s) -
Roy Saumendra P.,
Rahman Mohammad M.,
Yu Xiao Di,
Tuittila Minna,
Knight Stefan D.,
Zavialov Anton V.
Publication year - 2012
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12044
Subject(s) - biology , complementation , microbiology and biotechnology , chaperone (clinical) , enterotoxigenic escherichia coli , fibronectin , bacterial adhesin , extracellular matrix , biochemistry , escherichia coli , enterotoxin , medicine , pathology , gene , phenotype
Summary Coli surface antigen 6 ( CS 6) is a widely expressed enterotoxigenic E scherichia coli ( ETEC ) colonization factor that mediates bacterial attachment to the small intestinal epithelium. CS 6 is a polymer of two protein subunits CssA and CssB , which are secreted and assembled on the cell surface via the CssC / CssD chaperone usher ( CU ) pathway. Here, we present an atomic resolution model for the structure of CS 6 based on the results of X ‐ray crystallographic, spectroscopic and biochemical studies, and suggest a mechanism for CS 6‐mediated adhesion. We show that the CssA and CssB subunits are assembled alternately in linear fibres by the principle of donor strand complementation. This type of fibre assembly is novel for CU assembled adhesins. We also show that both subunits in the fibre bind to receptors on epithelial cells, and that CssB , but not CssA , specifically recognizes the extracellular matrix protein fibronectin. Taken together, structural and functional results suggest that CS 6 is an adhesive organelle of a novel type, a hetero‐polyadhesin that is capable of polyvalent attachment to different receptors.