| Title | 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 |
|---|---|
| Author | Minho Lee1, Hyun-Lee Kim1, Saemee Song1, Minju Joo1, Seunghwa Lee1, Daeyoung Kim1, Yoonsoo Hahn1, Nam-Chul Ha2, and Kangseok Lee1* |
| Address | 1Department of Life Science, Chung-Ang University, Seoul 156-756, Republic of Korea, 2Department of Manufacturing Pharmacy, Pusan National University, Busan 609-735, Republic of Korea |
| Bibliography | Journal of Microbiology, 51(2),154-159, 2013, |
| DOI | 10.1007/s12275-013-2699-3 |
| Key Words | MacA, MacB, TolC, TolCV1, TolCV2, Type I secretion system |
| 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. |