Current and Ongoing Projects:
The Class B tetracycline efflux pump in Enterobacteriaceae was the first drug efflux pump described and serves as a model for other active efflux systems for antibiotics and other toxic compounds. The Tet protein has 12 putative membrane spanning regions and is organized into two genetic domains (halves) each of which is needed to mediate efflux. Work in this area involves genetic and biochemical studies of the efflux protein itself and chemical synthesis of tetracycline derivatives to define the active site and to circumvent or block the efflux pump. One focus is directed at obtaining a 3D structure of the Tet protein.
- Levy, S.B. and L. McMurry (1974) Detection of an inducible membrane protein associated with R-factor-mediated tetracycline resistance. Biochem. Biophys. Res. Comm. 56:1060- 1068.
- McMurry, L.M., R. Petrucci and S.B. Levy (1980) Active efflux of tetracycline encoded by four genetically different tetracycline resistance determinants in E. coli. Proc. Natl. Acad. Sci. (U.S.A.) 77:3974-3977.
- Levy, S.B. (1992)Active efflux mechanisms for antimicrobial resistance.Antimicrob. Agents and Chemother. 36:695-703.
- Nelson, M.L., B.H. Park and S.B. Levy (1994)Molecular requirements for the inhibition of the tetracycline antiport protein and the effect of potent inhibitors on growth of tetracycline resistant bacteria.J. Med. Chem. 37:1355-1361.
- McMurry, L.M. and S.B. Levy(1995)The NH2-terminal half of the Tn10-specified tetracycline efflux protein TetA contains a dimerization domain.J. Biol. Chem. 270:22752-22757.
- Aldema, M.L., L.M. McMurry, A.R. Walmsley and S.B. Levy (1996)Purification of the Tn10-specified tetracycline efflux antiporter TetA in a native state as a polyhistidine. Molec. Microb. 19:187-195.
- Nelson, M.L. and S. B. Levy (1999) Reversal of tetracycline resistance mediated by different bacterial tetracycline resistance determinants by an inhibitor of the Tet(B) antiport protein.Antimicrob. Agts. Chemother. 43:1719-1724.
- Saraceni-Richards, C. and S.B. Levy (2000) Evidence for interactions between helices 5 and 8 and a role for the interdomain loop in tetracycline resistance mediated by hybrid Tet proteins.J. Biol. Chem 275:6101-6106.
- Saraceni-Richards, C. and S.B. Levy. (2000)Second site suppressor mutations of Gly-247 substitution mutants of the tetracycline efflux protein Tet(B) J. Bacteriol. 182: 6514-6516.
- Yin, C-C., M.L. Aldema-Ramos, I. Borges-Walmsley, R.W. Taylor, A.R. Walmsley, S.B. Levy and P.A. Bullough. (2000) The quarternary molecular architecture of TetA, a secondary tetracycline transporter from Escherichia coli Molec. Microb. 38: 482-492.McMurry, L.M. and S.B. Levy. (2002) Fe2+ -tetracycline-mediated cleavage of the Tn10 tetracycline efflux protein Teta reveals a substrate binding site near glutamine 225 in a transmembrane helix 7. J. Bacteriol. 184:5113-5120
- Nelson, M.L., M.Y. Ismail, B. Bhatia, P. Viski, G. Rennie, D. Andorsky, D. Messersmith, K. Stapleton, J. Dumornay, P. Sheahan, A.K. Verma, T. Warchol, and S.B. Levy (2003) Versatile and facile synthesis of diverse semisynthetic tetracycline derivatives via pd-catalyzed reactions. J. Org. Chem. 68:5838-5851
- Sapunaric, F. and and S.B. Levy (2005). Substitutions in the interdomain loop of the Tn10 TetA efflux protein alter tetracycline resistance and substrate specificity. Microbiology 151:2315-2322.
- McMurry, L.M. and S. B. Levy (2006) Tetracycline resistance determinants in gram-positive bacteria.In: Gram Positive Pathogens (Fischetti, V., R. Novick, J. Ferretti, D. Portnoy and J. Rood,eds.) ASM Press.
- Sapunaric, F. and S.B. Levy (2007). Interdomain loop mutation Asp190Cys of tetracycline
efflux transporter TetA(B) decreases affinity for substrate. Antimicrob. Agents
Chemother. 51: 3036-3037