Centre for Infection and Immunity, Queen's University Belfast, Belfast, United Kingdom.
Antimicrob Agents Chemother. 2013 Apr;57(4):1603-9. doi: 10.1128/AAC.01998-12. Epub 2013 Jan 14.
RarA is an AraC-type regulator in Klebsiella pneumoniae, which, when overexpressed, confers a low-level multidrug-resistant (MDR) phenotype linked to the upregulation of both the acrAB and oqxAB efflux genes. Increased rarA expression has also been shown to be integral in the development of tigecycline resistance in the absence of ramA in K. pneumoniae. Given its phenotypic role in MDR, microarray analyses were performed to determine the RarA regulon. Transcriptome analysis was undertaken using strains Ecl8ΔrarA/pACrarA-2 (rarA-expressing construct) and Ecl8ΔrarA/pACYC184 (vector-only control) using bespoke microarray slides consisting of probes derived from the genomic sequences of K. pneumoniae MGH 78578 (NC_009648.1) and Kp342 (NC_011283.1). Our results show that rarA overexpression resulted in the differential expression of 66 genes (42 upregulated and 24 downregulated). Under the COG (clusters of orthologous groups) functional classification, the majority of affected genes belonged to the category of cell envelope biogenesis and posttranslational modification, along with genes encoding the previously uncharacterized transport proteins (e.g., KPN_03141, sdaCB, and leuE) and the porin OmpF. However, genes associated with energy production and conversion and amino acid transport/metabolism (e.g., nuoA, narJ, and proWX) were found to be downregulated. Biolog phenotype analyses demonstrated that rarA overexpression confers enhanced growth of the overexpresser in the presence of several antibiotic classes (i.e., beta-lactams and fluoroquinolones), the antifungal/antiprotozoal compound clioquinol, disinfectants (8-hydroxyquinoline), protein synthesis inhibitors (i.e., minocycline and puromycin), membrane biogenesis agents (polymyxin B and amitriptyline), DNA synthesis (furaltadone), and the cytokinesis inhibitor (sanguinarine). Both our transcriptome and phenotypic microarray data support and extend the role of RarA in the MDR phenotype of K. pneumoniae.
RarA 是肺炎克雷伯菌中的一种 AraC 型调控因子，当过度表达时，会导致低水平的多药耐药 (MDR) 表型，与 acrAB 和 oqxAB 外排基因的上调有关。已经表明，rarA 表达的增加也是在肺炎克雷伯菌中没有 ramA 的情况下发展替加环素耐药的重要因素。鉴于其在 MDR 中的表型作用，进行了微阵列分析以确定 RarA 调节子。使用 Ecl8ΔrarA/pACrarA-2（rarA 表达构建体）和 Ecl8ΔrarA/pACYC184（载体对照）菌株进行转录组分析，使用来自肺炎克雷伯菌 MGH 78578（NC_009648.1）和 Kp342（NC_011283.1）基因组序列衍生的探针的定制微阵列载玻片进行分析。我们的结果表明，rarA 过表达导致 66 个基因的差异表达（42 个上调和 24 个下调）。在 COG（直系同源群聚类）功能分类下，受影响的大多数基因属于细胞包膜生物发生和翻译后修饰类别，以及先前未表征的转运蛋白（例如 KPN_03141、sdaCB 和 leuE）和孔蛋白 OmpF 的基因。然而，与能量产生和转化以及氨基酸运输/代谢相关的基因（例如 nuoA、narJ 和 proWX）被发现下调。Biolog 表型分析表明，rarA 过表达赋予了过表达菌在几种抗生素类（即β-内酰胺类和氟喹诺酮类）、抗真菌/抗原生动物化合物氯碘喹啉、消毒剂（8-羟基喹啉）、蛋白质合成抑制剂（即米诺环素和嘌呤霉素）、膜生物发生剂（多粘菌素 B 和阿米替林）、DNA 合成（呋喃他酮）和细胞分裂抑制剂（血根碱）中的生长增强。我们的转录组和表型微阵列数据都支持和扩展了 RarA 在肺炎克雷伯菌 MDR 表型中的作用。
