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

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 kno...

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Bibliographic Details
Published in:The Journal of biological chemistry 1999-12, Vol.274 (50), p.35969-35974
Main Authors: Delahay, R M, Knutton, S, Shaw, R K, Hartland, E L, Pallen, M J, Frankel, G
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Bacterial Proteins - chemistry
Bacterial Proteins - genetics
Bacterial Proteins - ultrastructure
Cell Membrane - physiology
Cloning, Molecular
Escherichia coli
Escherichia coli - genetics
Escherichia coli - pathogenicity
Escherichia coli Proteins
EspA protein
EspB protein
EspD protein
Molecular Sequence Data
Protein Structure, Quaternary
Protein Structure, Secondary
Recombinant Fusion Proteins - biosynthesis
Recombinant Fusion Proteins - chemistry
Signal Transduction
Software
Tir protein
Virulence
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Summary: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 alpha-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 A/E lesions; additional mutation totally abolished EspA filament assembly and A/E 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.
ISSN:0021-9258
DOI:10.1074/jbc.274.50.35969