Efflux permease CgAcr3-1 of Corynebacterium glutamicum is an arsenite-specific antiporter.

TitleEfflux permease CgAcr3-1 of Corynebacterium glutamicum is an arsenite-specific antiporter.
Publication TypeJournal Article
Year of Publication2012
AuthorsVilladangos, A. F., H-L. Fu, J. A. Gil, J. Messens, B. P. Rosen, and L. M. Mateos
JournalJ Biol Chem
Date Published2012 Jan 02
Type of Articleredox
KeywordsAmino Acid Sequence, Antiporters, Arsenites, Bacterial Proteins, Biocatalysis, Biological Transport, Cell Membrane, Corynebacterium glutamicum, Hydrogen-Ion Concentration, Hydrophobic and Hydrophilic Interactions, Membrane Potentials, Membrane Transport Proteins, Molecular Sequence Data, Mutagenesis, Site-Directed, Protein Structure, Tertiary, Protons, Sequence Homology, Amino Acid, Substrate Specificity

Resistance to arsenite (As(III)) by cells is generally accomplished by arsenite efflux permeases from Acr3 or ArsB unrelated families. We analyzed the function of three Acr3 proteins from Corynebacterium glutamicum, CgAcr3-1, CgAcr3-2, and CgAcr3-3. CgAcr3-1 conferred the highest level of As(III) resistance and accumulation in vivo. CgAcr3-1 was also the most active when everted membranes vesicles from Escherichia coli or C. glutamicum mutants were assayed for efflux with different energy sources. As(III) and antimonite (Sb(III)) resistance and accumulation studies using E. coli or C. glutamicum arsenite permease mutants clearly show that CgAcr3-1 is specific for As(III). In everted membrane vesicles expressing CgAcr3-1, dissipation of either the membrane potential or the pH gradient of the proton motive force did not prevent As(III) uptake, whereas dissipation of both components eliminated uptake. Further, a mutagenesis study of CgAcr3-1 suggested that a conserved cysteine and glutamate are involved in active transport. Therefore, we propose that CgAcr3-1 is an antiporter that catalyzes arsenite-proton exchange with residues Cys129 and Glu305 involved in efflux.

Alternate JournalJ. Biol. Chem.
PubMed ID22102279
PubMed Central IDPMC3249127
Grant ListR01 GM055425 / GM / NIGMS NIH HHS / United States
R37 GM055425 / GM / NIGMS NIH HHS / United States
GM55425 / GM / NIGMS NIH HHS / United States
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