title: Agrobacterium ParA/MinD-like VirC1 spatially coordinates early conjugative DNA transfer reactions.
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.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX 77030, USA.
authors.forename: Krishnamohan
authors.initials: K
authors.lastname: Atmakuri
authors.forename: Eric
authors.initials: E
authors.lastname: Cascales
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Burton
authors.forename: Lois M
authors.initials: LM
authors.lastname: Banta
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Christie
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016960:Agrobacterium tumefaciens / Q000472:pathogenicity*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D005982:Glutathione Transferase / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D010957:Plasmids; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D011994:Recombinant Proteins; D037521:Virulence Factors; D005982:Glutathione Transferase; D000251:Adenosine Triphosphatases