Disease relevance of virB11

• In this report, the product of virB11, an essential virulence gene, was overproduced in Escherichia coli and purified by using immunoaffinity chromatography [1].
• A partially sequenced tra gene directly upstream of nuc is homologous to the virB11 gene of Agrobacterium tumefaciens [2].
• The deduced VirB11 protein exhibits sequence similarity to comG ORF1, a protein required for uptake of DNA by competent Bacillus subtilis cells [1].
• A chimeric protein composed of VirB11 fused to the DNA binding domain of lambda cI repressor protein formed dimers, as shown by immunity of Escherichia coli to lambda superinfection [3].

High impact information on virB11

• We propose that the virB9, virB10, and virB11 gene products function coordinately and stoichiometrically to enhance DNA transfer in a fashion specific for the T-DNA intermediate [4].
• The DNA sequence analysis also revealed consensus mononucleotide binding domains in the deduced virB5 and virB11 gene products, suggesting that one or both of these proteins couple energy, by means of nucleotide triphosphate (NTP) hydrolysis, to T-DNA transport [1].
• VirB11 protein was localized primarily to the cytoplasmic membrane by immunoblot analysis of membrane fractions [1].
• These interactions were mapped onto the homology models to predict direct interactions between the hexameric interfaces of VirB4 and VirB11 such that the VirB4 C terminus stacks above VirB11 in the periplasm [5].
• Here, by TrIP, we show that nucleoside triphosphate binding site (Walker A motif) mutations do not disrupt VirD4 substrate binding or transfer to VirB11, suggesting that these early reactions proceed independently of ATP binding or hydrolysis [6].

Chemical compound and disease context of virB11

• To facilitate the further characterization of VirB11, we purified this protein from the soluble fraction of an Escherichia coli extract by fusing VirB11 to the maltose-binding protein [7].

Biological context of virB11

• In the large virB-operon (9600 nucleotides) we have identified eleven open reading frames, designated virB1 to virB11 [8].
• Due to the polarity of the transposon insertions, only the last gene in the operon, virB11, is known to provide an essential virulence function [9].
• Interestingly, both a membrane protein (VirB4) and a potential cytoplasmic protein (VirB11) contain the consensus amino acid sequence of ATP-binding proteins [8].
• The mutant genes did not exhibit a transdominant phenotype on tumor formation in bacteria that were expressing wild-type virB11 [7].
• Our earlier studies showed that the IncQ broad-host-range plasmid RSF1010, which can be transferred from Agrobacterium cells to plant cells, inhibits the transfer of T-DNA from pTiA6 in a fashion that is reversed by overexpression of virB9, virB10, and virB11 [10].

Anatomical context of virB11

• The virB operon on pRiA4 has been sequenced and found to be composed of 11 genes, virB1 to virB11, whose products mostly appear to be associated with the cell membrane [11].
• VirB11 was stripped from the membranes by 6 M urea but not by a more mild salt extraction [12].

Associations of virB11 with chemical compounds

• The maltose-binding protein-VirB11 fusion was able to complement a virB11 deletion mutant of A. tumefaciens for tumor formation and also localized properly to the inner membrane of A. tumefaciens [7].
• To study the importance of the Walker nucleotide-binding site present in VirB11, mutations were generated to replace the conserved lysine residue with either alanine or arginine [7].

Other interactions of virB11

• All dominant alleles were suppressed at least to some extent by multicopy expression of the virB9, virB10, and/or virB11 genes [13].
• Two derivatives, A348 delta B4.4 and A348 delta B4.5, sustained a nonpolar deletion of the wild-type virB4 allele, as judged by Southern blot hybridization and immunoblot analyses with antibodies specific for VirB4, VirB5, VirB10, and VirB11 [14].

Analytical, diagnostic and therapeutic context of virB11

• By co-immunoprecipitation, we supply evidence for VirD4 interactions with VirB4 and VirB11 independently of other T4SS subunits or intact Walker A motifs, and with the bitopic inner membrane subunit VirB10 [6].
• X-ray crystallography revealed that homologues of the A. tumefaciens inner membrane-associated proteins VirB11 and VirD4 from H. pylori and R388, respectively, may form channels for substrate translocation or assembly of the transmembrane TFSS machinery [15].
• In support of the titration model, a complex of native VirB11 and VirB11::GFP was recovered by precipitation with anti-GFP antibodies from detergent-solubilized A. tumefaciens cell extracts [3].

References