The coiled-coil domain of EspA is essential for the assembly of the type III secretion translocon on the surface of enteropathogenic Escherichia coli

Robin M. Delahay, Stuart Knutton, Robert K. Shaw, Elizabeth L. Hartland, Mark J. Pallen, Gad Frankel

Research output: Contribution to journalArticleResearchpeer-review

56 Citations (Scopus)

Abstract

Enteropathogenic E. coli (EPEC) utilize a type III secretion system to deliver virulence-associated effector proteins to the host cell. Four proteins, EspA, EspB, EspD, and Tir, which are integral to the formation of characteristic 'attaching and effacing' (A/E) intestinal lesions, are known to be exported via the EPEC type III secretion system. Recent work demonstrated that EspA is a major component of a filamentous structure, elaborated on the surface of EPEC, which is required for translocation of EspB and Tir. The carboxyl terminus of EspA is predicted to comprise an α- helical region, which demonstrates heptad periodicity whereby positions a and d in the heptad repeat unit abcdefg are occupied by hydrophobic residues, indicating a propensity for coiled-coil interactions. Here we demonstrate multimeric EspA isoforms in EPEC culture supernatants and EspA:EspA interaction on solid phase. Non-conservative amino acid substitution of specific EspA heptad residues generated EPEC mutants defective in filament assembly but which retained the ability to induce ArE lesions; additional mutation totally abolished EspA filament assembly and ArE lesion formation. These results demonstrate a similarity to flagellar biosynthesis and indicate that the coiled-coil domain of EspA is required for assembly of the EspA filament-associated type III secretion translocon.

Original languageEnglish
Pages (from-to)35969-35974
Number of pages6
JournalThe Journal of Biological Chemistry
Volume274
Issue number50
DOIs
Publication statusPublished - 10 Dec 1999

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