Hedger Jennifer, Holmquist Peter C, Leigh Kimberly A, Saraff Kumuda, Pomykal Christina, Summers Michael L
California State University Northridge, Department of Biology, 18111 Nordhoff St, Northridge, CA 91330, USA.
Amgen, Thousand Oaks, CA 91320, USA.
Microbiology (Reading). 2009 Sep;155(Pt 9):2994-3004. doi: 10.1099/mic.0.028035-0. Epub 2009 Jun 18.
The cAMP receptor protein (Crp) is a global transcriptional regulator that binds sequence-specific promoter elements when associated with cAMP. In the motile cyanobacterium Synechocystis sp. strain PCC 6803, intracellular cAMP increases when dark-adapted cells are illuminated. Previous work has established that Crp binds proposed Crp target sites upstream of slr1351 (murF), sll1874 (chlA(II)), sll1708 (narL), slr0442 and sll1268 in vitro, and that slr0442 is downregulated in a crp mutant during photoautotrophic growth. To identify additional Crp target genes in Synechocystis, 11 different Crp binding sites proposed during a previous computational survey were tested for in vitro sequence-specific binding and crp-dependent transcription. The results indicate that murF, chlA(II) and slr0442 can be added as 'target genes of Sycrp1' in Synechocystis. Promoter mapping of the targets revealed the same close association of RNA polymerase and Crp as that found in Escherichia coli class I and class II Crp-regulated promoters, thereby strongly suggesting similar mechanisms of transcriptional activation.
环磷酸腺苷受体蛋白（Crp）是一种全局转录调节因子，当与环磷酸腺苷结合时，它会结合序列特异性启动子元件。在运动型蓝藻集胞藻PCC 6803菌株中，暗适应细胞受光照时细胞内环磷酸腺苷会增加。先前的研究已经证实，Crp在体外可结合slr1351（murF）、sll1874（chlA(II)）、sll1708（narL）、slr0442和sll1268上游的假定Crp靶位点，并且在光合自养生长过程中，slr0442在crp突变体中表达下调。为了鉴定集胞藻中其他的Crp靶基因，对先前计算分析中提出的11个不同的Crp结合位点进行了体外序列特异性结合和crp依赖性转录测试。结果表明，murF、chlA(II)和slr0442可被添加到集胞藻中“Sycrp1的靶基因”列表中。对这些靶标的启动子定位显示，RNA聚合酶和Crp之间的紧密关联与在大肠杆菌I类和II类Crp调节启动子中发现的相同，从而强烈暗示了相似的转录激活机制。
