TCDB is operated by the Saier Lab Bioinformatics Group

1.B.38 The Treponema Porin Major Surface Protein (TP-MSP) Family

MSP is a 53 kDa (474 aa) surface antigen in the outer sheath of Treponema denticola. It is an adhesin, but additionally it has been purified to homogeneity and reconstituted in black lipid membranes where it showed channel activity (Egli et al., 1993). It also induces channel activity in HeLa cell membranes (Mathers et al., 1996). The channel had a single conductance of 1.8 nS in 0.1 M KCl (estimated pore diameter of 3.4 nm), the largest porin channel documented in 1996. Electron microscopy suggested a regular hexagonal array in the membrane. Homologues are found in other Treponema species.

The transport reaction catalyzed by MSP is:

ions (non-selective)(periplasm) ions (out)

References associated with 1.B.38 family:

Anand A., LeDoyt M., Karanian C., Luthra A., Koszelak-Rosenblum M., Malkowski MG., Puthenveetil R., Vinogradova O. and Radolf JD. (2015). Bipartite Topology of Treponema pallidum Repeat Proteins C/D and I: OUTER MEMBRANE INSERTION, TRIMERIZATION, AND PORIN FUNCTION REQUIRE A C-TERMINAL beta-BARREL DOMAIN. J Biol Chem. 290(19):12313-31. 25805501
Anand, A., A. Luthra, M.E. Edmond, M. Ledoyt, M.J. Caimano, and J.D. Radolf. (2013). The major outer sheath protein (Msp) of Treponema denticola has a bipartite domain architecture and exists as periplasmic and outer membrane-spanning conformers. J. Bacteriol. 195: 2060-2071. 23457251
Egli, C., W.K. Leung, K.H. Muller, R.E. Hancock, and B.C. McBride. (1993). Pore-forming properties of the major 53-kilodalton surface antigen from the outer sheath of Treponema denticola. Infect. Immun. 61: 1694-1699. 7682993
Giacani, L., S.L. Brandt, M. Puray-Chavez, T.B. Reid, C. Godornes, B.J. Molini, M. Benzler, J.S. Hartig, S.A. Lukehart, and A. Centurion-Lara. (2012). Comparative investigation of the genomic regions involved in antigenic variation of the TprK antigen among treponemal species, subspecies, and strains. J. Bacteriol. 194: 4208-4225. 22661689
Mathers, D.A., W.K. Leung, J.C. Fenno, Y. Hong, and B.C. McBride. (1996). The major surface protein complex of Treponema denticola depolarizes and induces ion channels in HeLa cell membranes. Infect. Immun. 64: 2904-2910. 8757811
Reid, T.B., B.J. Molini, M.C. Fernandez, and S.A. Lukehart. (2014). Antigenic variation of TprK facilitates development of secondary syphilis. Infect. Immun. 82: 4959-4967. 25225245