Department of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan.
J Antimicrob Chemother. 2011 May;66(5):1024-8. doi: 10.1093/jac/dkr049. Epub 2011 Feb 28.
To characterize the role of SmqnrR in the expression of Smqnr and SmtcrA, and the role of SmtcrA in drug resistance in Stenotrophomonas maltophilia.
SmqnrR, a DeoR-type regulator gene, is situated between a quinolone resistance gene (Smqnr) and a putative major facilitator superfamily transmembrane transporter gene (SmtcrA). To assess the regulatory role of SmQnrR in the expression of Smqnr and SmtcrA, the transcripts of Smqnr and SmtcrA genes were determined in the wild-type KJ and the SmqnrR isogenic mutant KJΔQnrR. An SmqnrR polar mutant, KJΔQnrRΩ, was constructed to investigate the possibility that SmqnrR and SmtcrA form an operon. The contribution of Smqnr and SmtcrA genes to the intrinsic and acquired resistance of S. maltophilia was evaluated using susceptibility testing.
SmQnrR acted as a repressor for the expression of Smqnr and SmtcrA genes. SmqnrR and SmtcrA genes formed an operon, which was negatively autoregulated by SmQnrR. Smqnr and SmtcrA contributed only slightly to intrinsic resistance in S. maltophilia. Nevertheless, overexpression of Smqnr and SmtcrA by inactivating SmqnrR conferred a slight increase in quinolone MICs and a more marked increase in tetracycline MIC.
The SmQnrR protein is a transcriptional repressor for the contiguous Smqnr and SmtcrA genes, and SmQnrR is a negative regulator of SmqnrR-SmtcrA operon expression. Inactivation of SmqnrR contributes to an acquired increase in quinolone and tetracycline MICs for S. maltophilia.
研究 SmqnrR 在 Smqnr 和 SmtcrA 表达中的作用以及 SmtcrA 在嗜麦芽寡养单胞菌耐药性中的作用。
SmqnrR 是一种 DeoR 型调控基因，位于喹诺酮类耐药基因（Smqnr）和假定的主要易化因子超家族跨膜转运蛋白基因（SmtcrA）之间。为了评估 SmQnrR 对 Smqnr 和 SmtcrA 表达的调控作用，测定了野生型 KJ 和 SmqnrR 同源缺失突变体 KJΔQnrR 中 Smqnr 和 SmtcrA 基因的转录本。构建 SmqnrR 极性突变体 KJΔQnrRΩ，以研究 SmqnrR 和 SmtcrA 是否形成操纵子。通过药敏试验评估 Smqnr 和 SmtcrA 基因对嗜麦芽寡养单胞菌固有和获得性耐药性的贡献。
SmQnrR 作为 Smqnr 和 SmtcrA 基因表达的抑制剂。SmqnrR 和 SmtcrA 基因形成一个操纵子，SmQnrR 对其进行负调控。Smqnr 和 SmtcrA 基因仅对嗜麦芽寡养单胞菌的固有耐药性略有贡献。然而，通过失活 SmqnrR 过度表达 Smqnr 和 SmtcrA 可导致喹诺酮 MIC 略有增加，四环素 MIC 显著增加。
SmQnrR 蛋白是连续的 Smqnr 和 SmtcrA 基因的转录抑制剂，SmQnrR 是 SmqnrR-SmtcrA 操纵子表达的负调控因子。SmqnrR 的失活有助于嗜麦芽寡养单胞菌对喹诺酮类和四环素类药物 MIC 的获得性增加。
