Disease relevance of virB1

• Characterization of the virB operon of an Agrobacterium tumefaciens Ti plasmid: nucleotide sequence and protein analysis [1].
• In a search for these additional genes, we have identified the rpoA gene, encoding the alpha subunit of RNA polymerase (RNAP), which confers significant expression of a virB promoter (virBp)::lacZ fusion in E. coli in the presence of an active transcriptional regulator virG gene [2].
• The Brucella suis virB operon is induced intracellularly in macrophages [3].

High impact information on virB1

• Fluorescence-activated cell sorter analysis and fluorescence microscopy showed that the virB promoter is induced in macrophages within 3 h after infection [3].
• These tra genes are homologous to and colinear with genes found in the virB operon of Agrobacterium tumefaciens Ti plasmids [4].
• The amino acid sequence of PtlC shows a high degree of homology to VirB4, a protein encoded by the virB operon, which contains 11 open reading frames that are involved in the transfer of T-DNA from Agrobacterium tumefaciens to the plant cells [5].
• A virGN54D mutant gene of M. loti caused constitutive expression of lacZ reporter gene fusions to virB1, virD4, msi059, and msi061 [6].
• The initiation of translation of five virB ORFs occurs at codons that overlap the termination codons of the ORF immediately upstream; thus, translational coupling may be an important mechanism for efficient translation of the large virB polycistronic mRNA [7].

Biological context of virB1

• To provide information relevant to understanding the function of VirB polypeptides, the nucleotide sequence of the virB operon from a nopaline plasmid, pTiC58, is presented here [7].
• Transposon mutagenesis studies have shown that virB gene products are required for virulence but their functions remain largely unknown [7].

Anatomical context of virB1

• Based on hydropathy plot analysis nine of the virB ORFs encode proteins that may interact with membranes; these data support the earlier hypothesis that virB gene products may form a membrane pore or channel to mediate exit of the T-DNA copy (T-strands) from Agrobacterium into the plant cell [7].

Associations of virB1 with chemical compounds

• A comparison of the two published octopine virB sequences with the nopaline sequence presented here is made [7].

Analytical, diagnostic and therapeutic context of virB1

• Flow cytometry used to measure green fluorescent protein expression from the virB promoter confirmed the data from slot blots [3].

References