CcpC, a novel regulator of the LysR family required for glucose repression of the citB gene in Bacillus subtilis
CcpC, a novel regulator of the LysR family required for glucose repression of the citB gene in Bacillus subtilis
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DOI：
10.1006/jmbi.1999.3420
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发表时间：
2000-01-28
影响因子：
5.6
通讯作者：
Sonenshein, AL
中科院分区：
文献类型：
--
作者：
Jourlin-Castelli, C;Mani, N;Sonenshein, AL
葡萄糖和2-酮戊二酸源对枯草芽孢杆菌乌头酸酶（citB）基因的协同碳分解代谢产物抑制依赖于位于该基因上游的DNA序列。以位置-66为中心的二分体对称元件中的突变和位置-27处的二分体对称的下游臂的重复中的突变引起去阻遏的citB表达。在这项工作中，一种能够与含有这些元件的DNA片段结合的蛋白质被纯化和鉴定。这种蛋白质被命名为CcpC（分解代谢物控制蛋白C），与转录调节因子LysR家族的成员具有序列相似性。除了与citB启动子结合外，CcpC还与citZ基因的启动子结合，citZ基因编码细胞的主要柠檬酸合酶并受到碳分解代谢物的抑制。在ccpC无效突变体中，citB和citZ的表达在葡萄糖-谷氨酰胺基本培养基中被去抑制，表明CcpC是citB和citZ基因表达的负调节因子。DNA酶I足迹实验表明，CcpC结合citB启动子区域内的两个位点，对应于二分体对称性和-27元件。在柠檬酸盐的存在下，一个假定的诱导剂，只有二分体对称元素是完全保护CcpC。当二分体对称元件发生突变时，CcpC不再能够与二分体对称或-27元件结合。在厌氧条件下，citB和citZ基因表达的抑制也被证明是由CcpC介导的。(C)北京大学出版社.
Synergistic carbon catabolite repression of the Bacillus subtilis aconitase (citB) gene by glucose and a source of 2-ketoglutarate is dependent on DNA sequences located upstream of the gene. Mutations in a dyad symmetry element centered at position -66 and in a repeat of the downstream arm of the dyad symmetry at position -27 cause derepressed citB expression. In this work, a protein able to bind to a DNA fragment containing these elements was purified and identified. This protein, named CcpC (Catabolite control protein C), shares sequence similarity with members of the LysR family of transcriptional regulators. In addition to binding to the citB promoter, CcpC bound to the promoter of the citZ gene, which encodes the cell's major citrate synthase and is subject to carbon catabolite repression. In a ccpC null mutant, expression of both citB and citZ was derepressed in glucose-glutamine minimal medium, indicating that CcpC is a negative regulator of citB and citZ gene expression. DNase I footprinting experiments showed that CcpC binds to two sites within the citB promoter region, corresponding to the dyad symmetry and -27 elements. In the presence of citrate, a putative inducer, only the dyad symmetry element was fully protected by CcpC. When the dyad symmetry element was mutated, CcpC was no longer able to bind to either the dyad symmetry or -27 elements. Repression of citB and citZ gene expression during anaerobiosis also proved to be mediated by CcpC. (C) 2000 Academic Press.