Identification of a bacterial type III effector family with G protein mimicry functions

Neal M. Alto, Feng Shao, Cheri S. Lazar, Renee L. Brost, Gordon Chua, Seema Mattoo, Stephen A. McMahon, Partho Ghosh, Timothy R. Hughes, Charles Boone, Jack E. Dixon

Research output: Contribution to journalArticlepeer-review

215 Scopus citations


Many bacterial pathogens use the type III secretion system to inject "effector" proteins into host cells. Here, we report the identification of a 24 member effector protein family found in pathogens including Salmonella, Shigella, and enteropathogenic E. coli. Members of this family subvert host cell function by mimicking the signaling properties of Ras-like GTPases. The effector IpgB2 stimulates cellular responses analogous to GTP-active RhoA, whereas IpgB1 and Map function as the active forms of Rac1 and Cdc42, respectively. These effectors do not bind guanine nucleotides or have sequences corresponding the conserved GTPase domain, suggesting that they are functional but not structural mimics. However, several of these effectors harbor intracellular targeting sequences that contribute to their signaling specificities. The activities of IpgB2, IpgB1, and Map are dependent on an invariant WxxxE motif found in numerous effectors leading to the speculation that they all function by a similar molecular mechanism.

Original languageEnglish (US)
Pages (from-to)133-145
Number of pages13
Issue number1
StatePublished - Jan 13 2006

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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