Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun 130062, People's Republic of China.
Can J Microbiol. 2013 May;59(5):304-10. doi: 10.1139/cjm-2012-0705. Epub 2013 Mar 19.
Yersinia pestis is one of the most dangerous pathogens. The cyclic AMP receptor protein (CRP) is required for the full virulence of Y. pestis, and it acts as a transcriptional regulator to control a large regulon, which includes several virulence-associated genes. The regulatory action of CRP is triggered only by binding to the small molecule cofactor cyclic AMP (cAMP). cAMP is synthesized from adenosine triphosphate by the adenylyl cyclase encoded by cyaA. In the present work, the regulation of crp and cyaA by CRP was investigated by primer extension, LacZ fusion, electrophoretic mobility shift assay, and DNase I footprinting. No transcriptional regulatory association between CRP and its own gene could be detected under the growth conditions tested. In contrast, CRP bound to a DNA site overlapping the core promoter -10 region of cyaA to repress the cyaA transcription. The determination of cellular cAMP levels further verified that CRP negatively controlled cAMP production. Repression of cAMP production by CRP through acting on the cAMP synthesase gene cyaA would represent a mechanism of negative automodulation of cellular CRP function.
鼠疫耶尔森菌是最危险的病原体之一。环腺苷酸受体蛋白（CRP）是鼠疫耶尔森菌完全毒力所必需的，它作为转录调节剂控制一个大的调控基因，其中包括几个与毒力相关的基因。CRP 的调节作用仅在与小分子辅助因子环腺苷酸（cAMP）结合时才被触发。cAMP 由 cyaA 编码的腺苷酸环化酶从三磷酸腺苷合成。在本工作中，通过引物延伸、LacZ 融合、电泳迁移率变动分析和 DNase I 足迹法研究了 CRP 对 crp 和 cyaA 的调节。在测试的生长条件下，未检测到 CRP 与其自身基因之间的转录调控关联。相比之下，CRP 与重叠 cyaA 核心启动子-10 区的 DNA 位点结合，抑制 cyaA 转录。细胞 cAMP 水平的测定进一步证实，CRP 通过作用于 cAMP 合成酶基因 cyaA 负调控 cAMP 的产生。CRP 通过作用于 cAMP 合成酶基因 cyaA 抑制 cAMP 的产生，这代表了细胞 CRP 功能负自动调节的一种机制。
