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Mobilization protein B This is a family of unknown function found in Bacteria. Family members include Mobilization protein B (MobB). MobB contains a putative membrane-spanning domain, and might be involved in anchoring or presenting MobA, and the covalently-linked plasmid DNA, to the conjugative pore for subsequent export. In agreement with this, MobB has been shown to be associated with the membrane. Deletion of the membrane-spanning domain disrupts this association and decreases the frequency of both type IV transport and plasmid mobilization. MobB is one out of three proteins encoded by RSF1010 that are required for its mobilization along with MobA and MobC. MobB encoded by the broad-host-range plasmid R1162 is required for its efficient transfer by conjugation. The C-terminal half of the protein contains a membrane domain essential for transfer, while the other, functionally active region of MobB, identified by mutagenesis, is at the N-terminal end. One mutation affecting this region inhibits replication, suggesting that this part of the protein is contacting and sequestering the relaxase-linked primase. A model that represents MobB molecules as anchored in the membrane at one end and engaging the relaxase at the other. This arrangement is suggested to increase the transfer frequency by raising the probability of contact between the relaxase and the membrane-embedded, coupling protein for type IV secretion. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",