The role of the T-pilus in horizontal gene transfer and tumorigenesis

The T-pilus is a flexuous filamentous appendage that is essential for Agrob acterium tumefaciens virulence. T-pilus subunits are derived from a VirB2-p rocessing reaction that generates cyclized polypeptide subunits. The T-pilu s filament has a diameter of 10 nm and contains a lumen approximately 2 nm in diameter. Biogenesis of the T-pilus requires all 11 VirB proteins, but n ot the VirD4 protein, which is used in conjugal plasmid transfer. VirB4 and VirB11 are two ATPases that may form homohexameric rings within the transp ort apparatus, which is composed of VirB6-10 proteins.