Transcription in the acetoin catabolic pathway is regulated by AcoR and CcpA in Bacillus thuringiensis
Transcription in the acetoin catabolic pathway is regulated by AcoR and CcpA in Bacillus thuringiensis
复制标题
苏云金芽孢杆菌中乙偶姻分解代谢途径的转录受 AcoR 和 CcpA 调节
DOI：
10.1016/j.micres.2020.126438
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发表时间：
2020-05-01
影响因子：
6.7
通讯作者：
Song, Fuping
中科院分区：
文献类型：
--
作者：
Peng, Qi;Zhao, Xin;Song, Fuping
乙偶姻（3 - 羟基 - 2 - 丁酮）是许多微生物中一种重要的生理代谢产物。乙偶姻的分解由乙偶姻脱氢酶系（AoDH ES）催化，该酶系由acoABCL操纵子编码。在本研究中，我们分析了苏云金芽孢杆菌（Bt）中aco操纵子的转录和调控。逆转录聚合酶链反应（RT - PCR）分析表明，acoABCL形成一个转录单元。受Sigma 54调控的共有序列位于距acoA转录起始位点（TSS）12个碱基对处。β - 半乳糖苷酶测定显示，aco操纵子的转录受乙偶姻诱导，由Sigma 54控制，并受AcoR正调控。AcoR的螺旋 - 转角 - 螺旋（HTH）结构域识别并特异性结合一个13碱基对的反向重复区域，该区域参与位于acoA转录起始位点上游81个碱基对处的30个碱基对的片段定位。AcoR中的GAF结构域抑制acoA启动子处的增强子转录活性。葡萄糖通过CcpA抑制aco操纵子和acoR的转录，并且CcpA特异性结合到acoR启动子片段内的序列上。在acoABCL和acoR突变体中，乙偶姻的利用被消除，这表明aco操纵子对乙偶姻的利用是必不可少的。此处呈现的数据增进了我们对细菌中aco基因簇调控的理解。
Acetoin (3-hydroxy-2-butanone) is an important physiological metabolic product in many microorganisms. Acetoin breakdown is catalyzed by the acetoin dehydrogenase enzyme system (AoDH ES), which is encoded by acoABCL operon. In this study, we analyzed transcription and regulation of the aco operon in Bacillus thuringiensis (Bt). RT-PCR analysis revealed that acoABCL forms one transcriptional unit. The Sigma 54 controlled consensus sequence was located 12 bp from the acoA transcriptional start site (TSS). beta-galactosidase assay revealed that aco operon transcription is induced by acetoin, controlled by sigma 54, and positively regulated by AcoR. The HTH domain of AcoR recognized and specifically bound to a 13-bp inverted repeat region that participates in 30-bp fragment mapping 81 bp upstream of the acoA TSS. The GAF domain in AcoR represses enhancer transcriptional activity at the acoA promoter. Transcriptions of the aco operon and acoR were repressed by glucose via CcpA, and CcpA specifically bound to sequences within the acoR promoter fragment. In the acoABCL and acoR mutants, acetoin use was abolished, suggesting that the aco operon is essential for utilization of acetoin. The data presented here improve our understanding of the regulation of the aco gene cluster in bacteria.