Brinkrolf Karina, Plöger Svenja, Solle Sandra, Brune Iris, Nentwich Svenja S, Hüser Andrea T, Kalinowski Jörn, Pühler Alfred, Tauch Andreas
International NRW Graduate School in Bioinformatics and Genome Research, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany.
Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany.
Microbiology (Reading). 2008 Apr;154(Pt 4):1068-1081. doi: 10.1099/mic.0.2007/014001-0.
The Cg1547 protein of Corynebacterium glutamicum ATCC 13032 is a member of the LacI/GalR family of DNA-binding transcriptional regulators. A defined deletion in the cg1547 gene, now designated uriR (uridine utilization regulator), resulted in the mutant strain C. glutamicum KB1547. Comparison of gene expression levels in C. glutamicum KB1547 and the wild-type strain revealed enhanced expression of the uriR operon genes cg1546 (ribokinase), cg1545 (uridine transporter) and cg1543 (uridine-preferring nucleoside hydrolase). Gene expression of the uriR operon was stimulated by the presence of either uridine or ribose. Growth assays with C. glutamicum mutants showed that functional Cg1543 and Cg1545 proteins are essential for the utilization of uridine as the sole carbon source. Transcriptional regulation of the uriR operon is mediated by a 29 bp palindromic sequence composed of two catabolite-responsive element (cre)-like sequences and located in between the mapped -10 promoter region and the start codon of uriR. A similar cre sequence was detected in the upstream region of rbsK2 (cg2554), coding for a second ribokinase in C. glutamicum ATCC 13032. DNA band-shift assays with a streptavidin-tagged UriR protein and labelled oligonucleotides including the cre-like sequences of uriR and rbsK2 demonstrated the specific binding of the purified regulator in vitro. Whole-genome DNA microarray hybridizations comparing the gene expression in C. glutamicum KB1547 with that of the wild-type strain revealed that UriR is a pathway-specific repressor of genes involved in uridine utilization in C. glutamicum.
谷氨酸棒杆菌ATCC 13032的Cg1547蛋白是DNA结合转录调节因子的LacI/GalR家族成员。cg1547基因（现命名为uriR，即尿苷利用调节因子）中的一个特定缺失导致了突变菌株谷氨酸棒杆菌KB1547。对谷氨酸棒杆菌KB1547和野生型菌株中基因表达水平的比较显示，uriR操纵子基因cg1546（核糖激酶）、cg1545（尿苷转运蛋白）和cg1543（尿苷偏好性核苷水解酶）的表达增强。uriR操纵子的基因表达受到尿苷或核糖的刺激。对谷氨酸棒杆菌突变体的生长测定表明，功能性的Cg1543和Cg1545蛋白对于将尿苷作为唯一碳源的利用至关重要。uriR操纵子的转录调控由一个29 bp的回文序列介导，该序列由两个类似分解代谢物反应元件（cre）的序列组成，位于定位的-10启动子区域和uriR的起始密码子之间。在编码谷氨酸棒杆菌ATCC 13032中第二种核糖激酶的rbsK2（cg2554）的上游区域检测到了类似的cre序列。用链霉亲和素标记的UriR蛋白和包含uriR和rbsK2的cre样序列的标记寡核苷酸进行的DNA带移分析证明了纯化的调节因子在体外的特异性结合。将谷氨酸棒杆菌KB1547与野生型菌株的基因表达进行比较的全基因组DNA微阵列杂交显示，UriR是谷氨酸棒杆菌中参与尿苷利用的基因的途径特异性阻遏物。
