Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, China.
School of Biological and Chemical Engineering, Ningbo Tech University, Ningbo, Zhejiang, China.
Appl Environ Microbiol. 2023 Oct 31;89(10):e0080223. doi: 10.1128/aem.00802-23. Epub 2023 Oct 6.
In a previous study, the novel gene cluster was found to be involved in salicylate degradation through the CoA-mediated pathway in sp. strain X9 (Mol Microbiol 116:783-793, 2021). In this study, an IclR family transcriptional regulator CehR4 was identified. In contrast to other regulators involved in salicylate degradation, forms one operon with the gentisyl-CoA thioesterase gene , while and (encoding salicylyl-CoA ligase and salicylyl-CoA hydroxylase, respectively) form another operon. and are divergently transcribed, and their promoters overlap. The results of the electrophoretic mobility shift assay and DNase I footprinting showed that CehR4 binds to the 42-bp motif between genes and , thus regulating transcription of and . The repeat sequences IR1 (5'-TTTATATAAA-3') and IR2 (5'-AATATAGAAA-3') in the motif are key sites for CehR4 binding. The arrangement of and and the conserved binding motif of CehR4 were also found in other bacterial genera. The results disclose the regulatory mechanism of salicylate degradation through the CoA pathway and expand knowledge about the systems controlled by IclR family transcriptional regulators.IMPORTANCEThe long-term residue of aromatic compounds in the environment has brought great threat to the environment and human health. Microbial degradation plays an important role in the elimination of aromatic compounds in the environment. Salicylate is a common intermediate metabolite in the degradation of various aromatic compounds. Recently, sp. strain X9, capable of degrading the pesticide carbaryl, was isolated from carbaryl-contaminated soil. Salicylate is the intermediate metabolite that appeared during the degradation of carbaryl, and a novel salicylate degradation pathway and the involved gene cluster have been identified. This study identified and characterized the IclR transcription regulator CehR4 that represses transcription of gene cluster. Additionally, the genetic arrangements of and and the binding sites of were also found in other bacterial genera. This study provides insights into the biodegradation of salicylate and provides an application in the bioremediation of aromatic compound-contaminated environments.
在之前的一项研究中,发现在 sp. 菌株 X9 中,通过 CoA 介导的途径,新型基因簇 参与水杨酸降解(Mol Microbiol 116:783-793, 2021)。在本研究中,鉴定出一个 IclR 家族转录调节因子 CehR4。与其他参与水杨酸降解的调节剂不同, 与 形成一个操纵子,而 与 (分别编码水杨酸-CoA 连接酶和水杨酸-CoA 羟化酶)形成另一个操纵子。 和 是反向转录的,它们的启动子重叠。电泳迁移率变动分析和 DNase I 足迹实验的结果表明,CehR4 结合到基因 和 之间的 42 个碱基对的模体上,从而调节 和 的转录。模体中的重复序列 IR1(5'-TTTATATAAA-3')和 IR2(5'-AATATAGAAA-3')是 CehR4 结合的关键位点。该模体中的 和 以及 CehR4 的保守结合模体在其他细菌属中也被发现。这些结果揭示了 CoA 途径下水杨酸降解的调控机制,并扩展了关于 IclR 家族转录调节因子控制的系统的知识。
环境中芳香族化合物的长期残留对环境和人类健康带来了巨大威胁。微生物降解在消除环境中的芳香族化合物方面发挥着重要作用。水杨酸是降解各种芳香族化合物过程中的常见中间代谢物。最近,从含有carbaryl 的土壤中分离出一株能够降解杀虫剂 carbaryl 的 sp. 菌株 X9。水杨酸是 carbaryl 降解过程中出现的中间代谢物,一个新的水杨酸降解途径和相关的基因簇 已经被鉴定出来。本研究鉴定并表征了 IclR 转录调节因子 CehR4,它抑制 基因簇的转录。此外,还发现了其他细菌属中的 和 以及 的结合位点的基因排列。本研究为水杨酸的生物降解提供了新的见解,并为芳香族化合物污染环境的生物修复提供了应用。