The Lactococcus lactis CodY regulon -: Identification of a conserved cis-regulatory element
The Lactococcus lactis CodY regulon -: Identification of a conserved cis-regulatory element
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DOI：
10.1074/jbc.m502349200
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发表时间：
2005-10-07
影响因子：
4.8
通讯作者：
Kuipers, OP
中科院分区：
文献类型：
--
作者：
den Hengst, CD;van Hijum, SAFT;Kuipers, OP
乳酸乳球菌MG1363的CodY是抑制蛋白水解系统的几个编码蛋白的基因的表达的转录调节因子。DNA微阵列分析，比较L。乳酸菌MG1363和其中codY突变的等基因菌株，用于确定CodY调节子。在富含肽的培养基和指数生长的细胞中，其中CodY发挥强抑制活性，在去除codY后超过30个基因的表达显著增加。差异表达的基因包括那些主要参与氨基酸转运和代谢。此外，属于其他功能类别的几个基因被去抑制，强调了CodY的多效性作用。用生物信息学工具仔细检查转录组数据，发现在L. lactis MG1363 Delta codY.证据表明，这15个碱基的顺式序列，AATTTTCWGAAAATT，作为一个高亲和力的结合位点CodY，电泳迁移率变动分析和DNA酶I足迹分析所示。该CodY盒的存在足以引起体内CodY介导的调节。该基序的拷贝也存在于codY自身的上游区域中。结果表明，CodY调节其自身的合成，并需要CodY盒和支链氨基酸与其启动子相互作用。
CodY of Lactococcus lactis MG1363 is a transcriptional regulator that represses the expression of several genes encoding proteins of the proteolytic system. DNA microarray analysis, comparing the expression profiles of L. lactis MG1363 and an isogenic strain in which codY was mutated, was used to determine the CodY regulon. In peptide-rich medium and exponentially growing cells, where CodY exerts strong repressing activity, the expression of over 30 genes was significantly increased upon removal of codY. The differentially expressed genes included those predominantly involved in amino acid transport and metabolism. In addition, several genes belonging to other functional categories were derepressed, stressing the pleiotropic role of CodY. Scrutinizing the transcriptome data with bioinformatics tools revealed the presence of a novel overrepresented motif in the upstream regions of several of the genes derepressed in L. lactis MG1363 Delta codY. Evidence is presented that this 15-bp cis-sequence, AATTTTCWGAAAATT, serves as a high affinity binding site for CodY, as shown by electrophoretic mobility shift assays and DNase I footprinting analyses. The presence of this CodY-box is sufficient to evoke CodY-mediated regulation in vivo. A copy of this motif is also present in the upstream region of codY itself. It is shown that CodY regulates its own synthesis and requires the CodY-box and branched-chain amino acids to interact with its promoter.