Unveiling the regulatory mechanisms of salicylate degradation gene cluster cehGHIR4 in Rhizobium sp. strain X9
Unveiling the regulatory mechanisms of salicylate degradation gene cluster cehGHIR4 in Rhizobium sp. strain X9
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DOI：
10.1128/aem.00802-23
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发表时间：
2023-10
影响因子：
4.4
通讯作者：
Zhijian Ke;Q. Zhu;Mingliang Zhang;Siyuan Gao;Mingli Jiang;Yidong Zhou;J. Qiu;Minggen Cheng
中科院分区：
文献类型：
--
作者：
Zhijian Ke;Q. Zhu;Mingliang Zhang;Siyuan Gao;Mingli Jiang;Yidong Zhou;J. Qiu;Minggen Cheng
在先前的一项研究中，发现新的基因簇cehGHI参与根瘤菌X9通过辅酶a介导的途径降解水杨酸（Mol Microbiol 116:783-793, 2021）。在这项研究中，发现了一个IclR家族转录调控因子CehR4。与其他参与水杨酸降解的调节因子不同，cehR4与龙胆碱-辅酶a硫酯酶基因cehI形成一个操纵子，而cehG和cehH（分别编码水杨酸-辅酶a连接酶和水杨酸-辅酶a羟化酶）形成另一个操纵子。cehGH和cehIR4是发散性转录的，它们的启动子重叠。电泳迁移迁移实验和dna酶I足迹分析结果表明，CehR4结合到cehH和cehI基因之间的42bp基序上，从而调控cehGH和cehIR4的转录。该基序中的重复序列IR1 （5 ' -TTTATATAAA-3 ‘）和IR2 （5 ’ -AATATAGAAA-3 '）是CehR4结合的关键位点。在其他细菌属中也发现了cehGH和cehIR4的排列以及CehR4的保守结合基序。研究结果揭示了CoA途径对水杨酸盐降解的调控机制，拓展了对IclR家族转录调控因子调控系统的认识。芳香化合物在环境中的长期残留给环境和人体健康带来了极大的威胁。微生物降解在环境中芳香族化合物的消除中起着重要作用。水杨酸盐是多种芳香族化合物降解过程中常见的中间代谢物。近年来，从被威威利污染的土壤中分离到一株能降解农药威威利的根瘤菌X9。水杨酸盐是西威因降解过程中出现的中间代谢物，发现了一条新的水杨酸盐降解途径及其涉及的基因簇cehGHIR4。本研究鉴定并鉴定了抑制cehGHIR4基因簇转录的IclR转录调节因子CehR4。此外，在其他细菌属中也发现了cehGH和cehIR4的遗传排列和CehR4的结合位点。该研究为水杨酸的生物降解提供了新的思路，并为芳香族化合物污染环境的生物修复提供了应用前景。芳香族化合物在环境中的长期残留给环境和人体健康带来了极大的威胁。微生物降解在环境中芳香族化合物的消除中起着重要作用。水杨酸盐是多种芳香族化合物降解过程中常见的中间代谢物。近年来，从被威威利污染的土壤中分离到一株能降解农药威威利的根瘤菌X9。水杨酸盐是西威因降解过程中出现的中间代谢物，发现了一条新的水杨酸盐降解途径及其涉及的基因簇cehGHIR4。本研究鉴定并鉴定了抑制cehGHIR4基因簇转录的IclR转录调节因子CehR4。此外，在其他细菌属中也发现了cehGH和cehIR4的遗传排列和CehR4的结合位点。该研究为水杨酸的生物降解提供了新的思路，并为芳香族化合物污染环境的生物修复提供了应用前景。
ABSTRACT In a previous study, the novel gene cluster cehGHI was found to be involved in salicylate degradation through the CoA-mediated pathway in Rhizobium 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, cehR4 forms one operon with the gentisyl-CoA thioesterase gene cehI, while cehG and cehH (encoding salicylyl-CoA ligase and salicylyl-CoA hydroxylase, respectively) form another operon. cehGH and cehIR4 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 cehH and cehI, thus regulating transcription of cehGH and cehIR4. The repeat sequences IR1 (5′-TTTATATAAA-3′) and IR2 (5′-AATATAGAAA-3′) in the motif are key sites for CehR4 binding. The arrangement of cehGH and cehIR4 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. IMPORTANCE The 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, Rhizobium 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 cehGHIR4 have been identified. This study identified and characterized the IclR transcription regulator CehR4 that represses transcription of cehGHIR4 gene cluster. Additionally, the genetic arrangements of cehGH and cehIR4 and the binding sites of CehR4 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. The 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, Rhizobium 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 cehGHIR4 have been identified. This study identified and characterized the IclR transcription regulator CehR4 that represses transcription of cehGHIR4 gene cluster. Additionally, the genetic arrangements of cehGH and cehIR4 and the binding sites of CehR4 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.