9.B.138 The Putative Mycobacterial Outer Membrane Porin, LprG (LprG; P27) Family

The P27-P55 (lprG-Rv1410c) operon is crucial for the survival of Mycobacterium tuberculosis during infection in mice. P55 encodes an MFS efflux pump (2.A.1.3.34) that has been shown to provide Mycobacterium smegmatis and Mycobacterium bovis BCG with resistance to several drugs, while P27 encodes a mannosylated lipoglycoprotein, previously described as an antigen that modulates the immune response against mycobacteria.

P27 and P55 function together through an efflux-pump mechanism. Deletion of the P27-P55 operon made M. tuberculosis susceptible to sodium dodecyl sulfate, suggesting that the lack of these proteins causes alterations in the cell wall permeability of the bacterium. Both P27 and P55 are required to restore wild type drug resistance phenotypes in the mutant (Bianco et al., 2011; Farrow and Rubin, 2008). LprG and LppX have been suggested to function as carriers of lipids, glycolipids or their derviatives in outer membrane biogenesis (Luthra et al., 2011).

This family belongs to the .



Bianco, M.V., F.C. Blanco, B. Imperiale, M.A. Forrellad, R.V. Rocha, L.I. Klepp, A.A. Cataldi, N. Morcillo, and F. Bigi. (2011). Role of P27 -P55 operon from Mycobacterium tuberculosis in the resistance to toxic compounds. BMC Infect Dis 11: 195.

Farrow, M.F. and E.J. Rubin. (2008). Function of a mycobacterial major facilitator superfamily pump requires a membrane-associated lipoprotein. J. Bacteriol. 190: 1783-1791.

Luthra, A., G. Zhu, D.C. Desrosiers, C.H. Eggers, V. Mulay, A. Anand, F.A. McArthur, F.B. Romano, M.J. Caimano, A.P. Heuck, M.G. Malkowski, and J.D. Radolf. (2011). The transition from closed to open conformation of Treponema pallidum outer membrane-associated lipoprotein TP0453 involves membrane sensing and integration by two amphipathic helices. J. Biol. Chem. 286: 41656-41668.


TC#NameOrganismal TypeExample

LprG (P27) lipoprotein


LprG of Mycobacterium tuberculosis (P0A518)


LppX lipoprotein


LppX of Mycobacterium tuberculosis (P65306)