VirB10 forms part of core complex in Type IV secretion system (T4SS)
This family contains VirB10, a component of the type IV secretion system (T4SS), including homologs TrbI, TraF, TrwE and TraL. T4S system is employed by pathogenic bacteria to export virulence DNAs and/or proteins directly from the bacterial cytoplasm into the host cell. It forms a large multiprotein complex consisting of 12 proteins termed VirB1-11 and VirD4. VirB10, interacts with VirB7 and VirB9, forming the membrane-spanning 'core complex' (CC), around which all other components assemble. The CC is inserted in both, the outer and inner membranes, playing a fundamental role as a scaffold for the rest of the T4SS components and actively participating in T4S substrate transfer through the bacterial envelope via conformational changes regulating channel opening and closing. TrwE in R33 plasmid has been shown to be anchored to the inner membrane and its C-terminal is necessary for conjugation; the transmembrane domains of TrwB and TrwE are involved in TrwB-TrwE interactions. TraF protein of the RP4 plasmid is involved in circularization of pilin subunits of P-type pili. In gonococcal genetic island (GGI) of Neisseria gonorrhoeae, T4SS encodes TrbI and circularization occurs via a covalent intermediate between the C terminus of putative pilin protein TraA and TrbI.
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