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New tools in an old trade: CS1 pilus morphogenesis
Author(s) -
Sakellaris Harry,
Scott June R.
Publication year - 1998
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 - 10.1046/j.1365-2958.1998.01088.x
Subject(s) - pilus , pilin , biology , periplasmic space , bacterial outer membrane , fimbriae proteins , protein subunit , operon , microbiology and biotechnology , genetics , escherichia coli , gene
CS1 pili serve as the prototype for a large class of serologically distinct pili associated with enterotoxigenic Escherichia coli that cause diarrhoea in humans. The four genes essential for CS1 pilus morphogenesis, cooB , A , C and D , are arranged in an operon and encode structural and assembly proteins unlike those of other pilus systems commonly associated with Gram‐negative bacteria. CS1 pili are composed primarily of the major pilin subunit, CooA, which determines the serological type of the pilus. The major pilin subunit is assembled into pili by the proteins CooB, CooC and CooD. CooD is both a minor component found at the pilus tip and an essential assembly protein, whereas CooC is an outer membrane protein thought to be involved in pilin transport. CooB is a novel periplasmic chaperone‐like protein that forms intermolecular complexes with and stabilizes the major and minor pilins. Unlike other pilin chaperones, CooB also stabilizes the outer membrane component of the assembly system, CooC. The proteins of CS1 pili have no significant homology to those of the well‐characterized Pap (pyelonephritis‐associated) pili and related systems, although most of the features of pilus morphogenesis are similar. Therefore, these appear to be among the rare cases of convergent evolution. Thus, for CS1 pili, enterotoxigenic E. coli use new protein ‘tools’ in the old ‘trade’ of forming functional pili.