ArticleThe Journal of antimicrobial chemotherapy2023
The role of TMS 12 in the staphylococcal multidrug efflux protein QacA.
Article in The Journal of antimicrobial chemotherapy, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
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Who cites it
2 citing papers in PubMed, 2 citations in OpenAlex.
- Is CepA frommSphere · 2025Article
- Cryo-EM structure of antibacterial efflux transporter QacA from Staphylococcus aureus reveals a novel extracellular loop with allosteric role.The EMBO journal · 2023Article
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Authors and funding
3 authors at 1 institution in 1 country.
Funding
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Abstract
objectivesTo elucidate the importance of a region in QacA predicted to be important in antimicrobial substrate recognition.
methodsA total of 38 amino acid residues within or flanking putative transmembrane helix segment (TMS) 12 of QacA were individually replaced with cysteine using site-directed mutagenesis. The impact of these mutations on protein expression, drug resistance, transport activity and interaction with sulphhydryl-binding compounds was determined.
resultsAccessibility analysis of cysteine-substituted mutants identified the extents of TMS 12, which allowed for refinement of the QacA topology model. Mutation of Gly-361, Gly-379 and Ser-387 in QacA resulted in reduced resistance to at least one bivalent substrate. Interaction with sulphhydryl-binding compounds in efflux and binding assays demonstrated the role of Gly-361 and Ser-387 in the binding and transport pathway of specific substrates. The highly conserved residue Gly-379 was found to be important for the transport of bivalent substrates, commensurate with the role of glycine residues in helical flexibility and interhelical interactions.
conclusionsTMS 12 and its external flanking loop is required for the structural and functional integrity of QacA and contains amino acids directly involved in the interaction with substrates.
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