VirB10 and similar proteins form part of core complex in Type IV secretion system (T4SS)
This family contains VirB10, a component of the type IV secretion system (T4SS) and its homologs, including TraB, TraF, IcmE, and similar proteins. 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. In Gram-negative bacterial pathogen Helicobacter pylori, an important aetiological agent of gastroduodenal disease in humans, the comB3 gene encodes protein with best homologies to TraS/TraB from the Pseudomonas aeruginosa conjugative plasmid RP1 and TrbI of plasmid RP4 and VirB10 from the Ti plasmid of Agrobacterium tumefaciens, as well as DotG/IcmE of Legionella pneumophila.