Different functions of MdtB and MdtC subunits in the heterotrimeric efflux transporter MdtB(2)C complex of Escherichia coli.

Biochemistry
Hong-Suk Kim, Hiroshi Nikaido

Abstract

In contrast to homotrimeric transporters of the RND (resistance-nodulation-division) superfamily, which often conduct efflux transport of a wide range of substrates by the functionally rotating mechanism, the mechanism utilized by the heterotrimeric members of this family, which also perform multidrug efflux, is unclear. We examined one heterotrimeric transporter, the MdtB(2)C complex of Escherichia coli, by an extensive cysteine scanning mutagenesis of residues likely involved in ligand transport. Many such mutations in MdtC strongly decreased the level of cloxacillin transport, whereas mutations of corresponding residues in MdtB did not affect transport. Furthermore, many such residues in MdtC were covalently modified by fluorescein maleimide, which acted as a substrate and presumably produced labeling of the residues in the substrate path. In contrast, few residues in MdtB were labeled. Together with the previous data showing that the inactivation of proton translocation channel in MdtC has an only modest effect on transport yet in MdtB totally inactivated the activity, these results suggest that the two subunits, MdtB and MdtC, play very different roles, MdtC likely involved in substrate binding and transport and MdtB presu...Continue Reading

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Citations

Feb 23, 2013·Plasmid·Anthony G Vecchiarelli, Barbara E Funnell
Apr 8, 2014·Annual Review of Biophysics·Jared A DelmarEdward W Yu
Aug 11, 2015·Protein Science : a Publication of the Protein Society·Jared A DelmarEdward W Yu
Jun 27, 2015·Frontiers in Microbiology·João AnesMarta Martins
Mar 12, 2015·Frontiers in Microbiology·Helen I ZgurskayaDavid Wolloscheck
Mar 20, 2015·Clinical Microbiology Reviews·Xian-Zhi LiHiroshi Nikaido
Jan 26, 2013·FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology·Thais Bergamin LimaOctávio Luiz Franco
Aug 20, 2019·Antimicrobial Resistance and Infection Control·Giorgio CasaburiMark A Underwood
Jul 14, 2018·Nature Reviews. Microbiology·Dijun DuBen F Luisi
Oct 8, 2019·Annals of the New York Academy of Sciences·Jessica KobylkaKlaas M Pos
Feb 28, 2021·Biotechnology and Bioengineering·José M Salvador López, Inge N A Van Bogaert

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