This family contains the C-terminal domain of transfer protein TraM of the G+ broad host range Enterococcus conjugative plasmid pIP501 and similar proteins. The protein localizes to the cell envelope and is part of the plasmid transfer system that is accessible from outside of the cell. TraM displays a fold similar to the type IV secretion system (T4SS) VirB8 proteins from A. tumefaciens and B. suis (G-) and to the transfer protein TcpC from C. perfringens plasmid pCW3 (G+), reinforcing the prediction that TraM performs a key role in the secretion process, which is underlined by its surface accessibility. It is also structurally related to members of the nuclear transport factor-2 (NTF-2)-like superfamily with a high similarity to the NTF-2 protein from Rattus norvegicus. TraM (categorized as T4SS VirB8-like class GAMMA) does not possess the binding pocket of classic VirB8 class ALPHA proteins, recognized by VirB8 interaction inhibitors.
Comment:structure, molecular dynamics, and cross-linking studies indicate that a TraM trimer acts as the biological unit; trimerization is facilitated by the N-terminal coiled-coil motif
Structure:4EC6: Enterococcus faecalis Ntf2-like (potential transfer protein Tram) homotrimer; contacts at 4.0A
Jiyao W et al.(2023). "The conserved domain database in 2023.",