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EMBO J. 2007 May 16;26(10):2540-51.

Agrobacterium ParA/MinD-like VirC1 spatially coordinates early conjugative DNA transfer reactions.

Author information

1
Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX 77030, USA.

Abstract

Agrobacterium tumefaciens translocates T-DNA through a polar VirB/D4 type IV secretion (T4S) system. VirC1, a factor required for efficient T-DNA transfer, bears a deviant Walker A and other sequence motifs characteristic of ParA and MinD ATPases. Here, we show that VirC1 promotes conjugative T-DNA transfer by stimulating generation of multiple copies per cell of the T-DNA substrate (T-complex) through pairwise interactions with the processing factors VirD2 relaxase, VirC2, and VirD1. VirC1 also associates with the polar membrane and recruits T-complexes to cell poles, the site of VirB/D4 T4S machine assembly. VirC1 Walker A mutations abrogate T-complex generation and polar recruitment, whereas the native protein recruits T-complexes to cell poles independently of other polar processing factors (VirC2, VirD1) or T4S components (VirD4 substrate receptor, VirB channel subunits). We propose that A. tumefaciens has appropriated a progenitor ParA/MinD-like ATPase to promote conjugative DNA transfer by: (i) nucleating relaxosome assembly at oriT-like T-DNA border sequences and (ii) spatially positioning the transfer intermediate at the cell pole to coordinate substrate-T4S channel docking.

PMID:
17505518
PMCID:
PMC1868908
DOI:
10.1038/sj.emboj.7601696
[Indexed for MEDLINE]
Free PMC Article

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