Journal of Microbiology

Research Support, Non-U.S. Gov't

The α-Barrel Tip Region of Escherichia coli TolC Homologs of Vibrio vulnificus Interacts with the MacA Protein to Form the Functional Macrolide-Specific Efflux Pump MacAB-TolC: Minho Lee , Hyun-Lee Kim , Saemee Song , Minju Joo , Seunghwa Lee , Daeyoung Kim , Yoonsoo Hahn , Nam-Chul Ha , Kangseok Lee; J. Microbiol. 2013;51(2):154-159. Published online April 27, 2013; DOI: https://doi.org/10.1007/s12275-013-2699-3

Abstract: TolC and its homologous family of proteins are outer membrane factors that are essential for exporting small molecules and toxins across the outer membrane in Gram-negative bacteria. Two open reading frames in the Vibrio vulnificus genome that encode proteins homologous to Escherichia coli TolC, designated TolCV1 and TolCV2, have 51.3% and 29.6% amino acid identity to TolC, respectively. In this study, we show that TolCV1 and TolCV2 functionally and physically interacted with the membrane fusion protein, MacA, a component of the macrolide-specific MacAB-TolC pump of E. coli. We further show that the conserved residues located at the aperture tip region of the α-hairpin of TolCV1 and TolCV2 played an essential role in the formation of the functional MacAB-TolC pump using site-directed mutational analyses. Our findings suggest that these outer membrane factors have conserved tip-to-tip interaction with the MacA membrane fusion protein for action of the drug efflux pump in Gramnegative bacteria.

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