Agrobacterium tumefaciens type IV secretion protein VirB3 is an inner membrane protein and requires VirB4, VirB7, and VirB8 for stabilization.

ABSTRACT: Agrobacterium tumefaciens VirB proteins assemble a type IV secretion apparatus and a T-pilus for secretion of DNA and proteins into plant cells. The pilin-like protein VirB3, a membrane protein of unknown topology, is required for the assembly of the T-pilus and for T-DNA secretion. Using PhoA and green fluorescent protein (GFP) as periplasmic and cytoplasmic reporters, respectively, we demonstrate that VirB3 contains two membrane-spanning domains and that both the N and C termini of the protein reside in the cytoplasm. Fusion proteins with GFP at the N or C terminus of VirB3 were fluorescent and, like VirB3, localized to a cell pole. Biochemical fractionation studies demonstrated that VirB3 proteins encoded by three Ti plasmids, the octopine Ti plasmid pTiA6NC, the supervirulent plasmid p

SUBMITTER: Mossey P 

PROVIDER: S-EPMC2876495 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature