A family of lysozyme-like virulence factors in bacterial pathogens of plants and animals

Arcady R. Mushegian, Karla Jean Fullner, Eugene V. Koonin, Eugene W. Nester*

*Corresponding author for this work

Research output: Contribution to journalArticle

89 Scopus citations

Abstract

We describe a conserved family of bacterial gene products that includes the VirB1 virulence factor encoded by tumor-inducing plasmids of Agrobacterium spp., proteins involved in conjugative DNA transfer of broad- host-range bacterial plasmids, and gene products that may be involved in invasion by Shigella spp. and Salmonella enterica. Sequence analysis and structural modeling show that the proteins in this group are related to chicken egg white lysozyme and are likely to adopt a lysozyme-like structural fold. Based on their similarity to lysozyme, we predict that these proteins have glycosidase activity. Iterative data base searches with three conserved sequence motifs from this protein family detect a more distant relationship to bacterial and bacteriophage lytic transglycosylases, and goose egg white lysozyme. Two acidic residues in the VirB1 protein of Agrobacterium tumefaciens form a putative catalytic dyad. Each of these residues was changed into the corresponding amide by site-directed mutagenesis. Strains of A. tumefaciens that express mutated VirB1 proteins have a significantly reduced virulence. We hypothesize that many bacterial proteins involved in export of macromolecules belong to a widespread class of hydrolases and cleave β-1,4-glycosidic bonds as part of their function.

Original languageEnglish (US)
Pages (from-to)7321-7326
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume93
Issue number14
DOIs
StatePublished - Jul 9 1996

Keywords

  • Agrobacterium
  • conjugative DNA transfer
  • glycosidase
  • invasion
  • virB genes

ASJC Scopus subject areas

  • General

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