ChvD, a chromosomally encoded ATP-binding cassette transporter-homologous protein involved in regulation of virulence gene expression in Agrobacterium tumefaciens

Zhenying Liu, Mark Jacobs, Dennis A. Schaff, Colleen A. McCullen, Andrew N. Binns

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

A yeast two-hybrid screen searching for chromosomally encoded proteins that interact with the Agrobacterium tumefaciens VirB8 protein was carried out. This screen identified an interaction candidate homologous to the partial sequence of a gene that had previously been identified in a transposon screen as a potential regulator of virG expression, chvD. In this report, the cloning of the entire chvD gene is described and the gene is sequenced and characterized. Insertion of a promoterless lacZ gene into the chvD locus greatly attenuated virulence and vir gene expression. Compared to that of the wild-type strain, growth of the chvD mutant was reduced in rich, but not minimal, medium. Expression of chvD, as monitored by expression of β-galactosidase activity from the chvD-lacZ fusion, occurred in both rich and minimal media as well as under conditions that induce virulence gene expression. The ChvD protein is highly homologous to a family of ATP-binding cassette transporters involved in antibiotic export from bacteria and has two complete Walker box motifs. Molecular genetic analysis demonstrated that disruption of either Walker A box, singly, does not inactivate this protein's effect on virulence but that mutations in both Walker A boxes renders it incapable of complementing a chvD mutant strain. Constitutive expression of virG in the chvD mutant strain restored virulence, supporting the hypothesis that ChvD controls virulence through effects on virG expression.

Original languageEnglish (US)
Pages (from-to)3310-3317
Number of pages8
JournalJournal of bacteriology
Volume183
Issue number11
DOIs
StatePublished - Jun 1 2001

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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