1.B.50 The Acid-fast Bacterial, Outer Membrane Porin (AFB-OMP) Family Mycobacteria contain an outer membrane composed of mycolic acids and a large variety of other lipids. Its protective function is an essential virulence factor of Mycobacterium tuberculosis. Rv1698 was predicted to be an outer membrane protein. Expression of rv1698 restored the sensitivity to ampicillin and chloramphenicol of a mutant of Mycobacterium smegmatis lacking the main porin MspA. Rv1698 complements the permeability defect of the M. smegmatis porin mutant for glucose and is surface-accessible (Siroy et al., 2008). Lipid bilayer experiments demonstrated that purified Rv1698 is an integral membrane protein which produces channels. The main conductance is 4.5 /- 0.3 nS in 1 M KCl with weak preference for cations. Thus, Rv1698 is a channel protein that is likely involved in transport processes across the outer membrane of M. tuberculosis. Rv1698 has single homologs in Corynebacterineae and is the first characterized member of a new class of channel proteins specific for mycolic acid-containing outer membranes. Homologues are present in other low and high G C Gram-positive bacteria, Gram-negative bacteria, and Archaea with outer mycolic acid-containing membranes. Rv1698 is distantly related to 9.A.42.1.1 (O53943).
References:
Siroy, A., C. Mailaender, D. Harder, S. Koerber, F. Wolschendorf, O. Danilchanka, Y. Wang, C. Heinz, and M. Niederweis. (2008). Rv1698 of Mycobacterium tuberculosis represents a new class of channel-forming outer membrane proteins. J. Biol. Chem. 283: 17827-17837.
Wolschendorf, F., D. Ackart, T.B. Shrestha, L. Hascall-Dove, S. Nolan, G. Lamichhane, Y. Wang, S.H. Bossmann, R.J. Basaraba, and M. Niederweis. (2011). Copper resistance is essential for virulence of Mycobacterium tuberculosis. Proc. Natl. Acad. Sci. USA 108: 1621-1626.
Examples:
TC#	Name	Organismal Type	Example
1.B.50.1.1	*Outer membrane porin, Rv1698 (314aas). Rv1698 accumulates 100-fold more Cu than WT (Wolschendorf et al., 2011).*	Acid-fast Gram-positive bacteria	*Rv1698 of Mycobacterium tuberculosis* (P64883)**

1.B.50.1.2	DUF3186 protein	Actinobacteria	DUF3186 protein of Actinomyces odontolyticus

Examples:
TC#	Name	Organismal Type	Example
1.B.50.2.1	Uncharacterized protein of 296 aas	Firmicutes	UP of Desulfotomaculum acetoxidans

1.B.50.2.2	Exported protein of 291 aas	Firmicutes	Exported protein of Clostridium difficile

1.B.50.2.3	Uncharacterized protein of 289 aas	Armalimonadetes	UP of Chthonomonas calidirosea