Ren-Hsuan Ku, Hsu-Feng Lu, Li-Hua Li, Ting-Yu Yeh, Yi-Tsung Lin, Tsuey-Ching Yang
{"title":"Roles of the <i>rpoEc-chrR-chrA</i> operon in superoxide tolerance and β-lactam susceptibility of <i>Stenotrophomonas maltophilia</i>.","authors":"Ren-Hsuan Ku, Hsu-Feng Lu, Li-Hua Li, Ting-Yu Yeh, Yi-Tsung Lin, Tsuey-Ching Yang","doi":"10.3389/fcimb.2025.1492008","DOIUrl":null,"url":null,"abstract":"<p><strong>Introduction: </strong>The <i>rpoE-chrR</i> pair is a regulatory system used by photosynthetic microorganisms to overcome singlet oxygen stress. <i>rpoE</i> and <i>chrR</i> encode the sigma factor σ<sup>E</sup> and anti-sigma factor ChrR, respectively. Stenotrophomonas maltophilia, an opportunistic pathogen, is a multidrug-resistant gram-negative bacterium. Although it is not a photosynthetic microorganism, a <i>rpoE-chrR</i> homolog (<i>smlt2377-smlt2378</i>) was found in the <i>S. maltophilia</i> genome. In this study, we aimed to assess the significance of σ<sup>Ec</sup>-ChrR pair in oxidative stress alleviation and antibiotic susceptibility of <i>S. maltophilia</i> KJ.</p><p><strong>Methods: </strong>Reverse transcription-polymerase chain reaction was used to validate the presence of operon. The contribution of <i>rpoEc-chrR-chrA</i> operon to oxidative stress alleviation and antibiotic susceptibility was evaluated using mutant constructs and stress-tolerance assays. RNA-seq transcriptome assay of wild-type KJ, KJΔChrR (<i>chrR</i> mutant), and KJΔChrRΔRpoEc (<i>chrR/rpoEc</i> double mutant) was performed to reveal the σ<sup>Ec</sup> regulon.</p><p><strong>Results: </strong>The <i>rpoEc-chrR</i> pair and downstream chrA formed an operon. Inactivation of <i>chrR</i> upregulated the expression of <i>rpoEc-chrR-chrA</i> operon in an σ<sup>Ec</sup>- and ChrA-dependent manner. σ<sup>Ec</sup> activation contributed to superoxide tolerance and increased β-lactam susceptibility but did not affect the tolerance to singlet oxygen and hydrogen peroxide. Transcriptome analysis revealed that expression of the nine-gene cluster, <i>smlt2375-smlt2367</i>, was significantly upregulated in KJΔChrR and reverted to the wild-type level in KJΔChrRΔRpoEc. <i>smlt2375-smlt2367</i> cluster was located upstream of the <i>rpoEc-chrR-chrA</i> operon and divergently transcribed, seeming to be involved in membrane lipid modification. Deletion of <i>smlt2375-smlt2367</i> cluster from the chromosome of KJΔChrR reverted the superoxide tolerance and β-lactam susceptibility to the wild-type level.</p><p><strong>Discussion: </strong>The <i>rpoEc-chrR</i> pair of <i>S. maltophilia</i> was involved in superoxide tolerance and β-lactam susceptibility. Notably, a novel regulatory circuit involving <i>rpoEc-chrR-chrA</i> operon and <i>smlt2375-smlt2367</i> cluster was revealed.</p>","PeriodicalId":12458,"journal":{"name":"Frontiers in Cellular and Infection Microbiology","volume":"15 ","pages":"1492008"},"PeriodicalIF":4.6000,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11832516/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Frontiers in Cellular and Infection Microbiology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.3389/fcimb.2025.1492008","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/1/1 0:00:00","PubModel":"eCollection","JCR":"Q2","JCRName":"IMMUNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Introduction: The rpoE-chrR pair is a regulatory system used by photosynthetic microorganisms to overcome singlet oxygen stress. rpoE and chrR encode the sigma factor σE and anti-sigma factor ChrR, respectively. Stenotrophomonas maltophilia, an opportunistic pathogen, is a multidrug-resistant gram-negative bacterium. Although it is not a photosynthetic microorganism, a rpoE-chrR homolog (smlt2377-smlt2378) was found in the S. maltophilia genome. In this study, we aimed to assess the significance of σEc-ChrR pair in oxidative stress alleviation and antibiotic susceptibility of S. maltophilia KJ.
Methods: Reverse transcription-polymerase chain reaction was used to validate the presence of operon. The contribution of rpoEc-chrR-chrA operon to oxidative stress alleviation and antibiotic susceptibility was evaluated using mutant constructs and stress-tolerance assays. RNA-seq transcriptome assay of wild-type KJ, KJΔChrR (chrR mutant), and KJΔChrRΔRpoEc (chrR/rpoEc double mutant) was performed to reveal the σEc regulon.
Results: The rpoEc-chrR pair and downstream chrA formed an operon. Inactivation of chrR upregulated the expression of rpoEc-chrR-chrA operon in an σEc- and ChrA-dependent manner. σEc activation contributed to superoxide tolerance and increased β-lactam susceptibility but did not affect the tolerance to singlet oxygen and hydrogen peroxide. Transcriptome analysis revealed that expression of the nine-gene cluster, smlt2375-smlt2367, was significantly upregulated in KJΔChrR and reverted to the wild-type level in KJΔChrRΔRpoEc. smlt2375-smlt2367 cluster was located upstream of the rpoEc-chrR-chrA operon and divergently transcribed, seeming to be involved in membrane lipid modification. Deletion of smlt2375-smlt2367 cluster from the chromosome of KJΔChrR reverted the superoxide tolerance and β-lactam susceptibility to the wild-type level.
Discussion: The rpoEc-chrR pair of S. maltophilia was involved in superoxide tolerance and β-lactam susceptibility. Notably, a novel regulatory circuit involving rpoEc-chrR-chrA operon and smlt2375-smlt2367 cluster was revealed.
期刊介绍：
Frontiers in Cellular and Infection Microbiology is a leading specialty journal, publishing rigorously peer-reviewed research across all pathogenic microorganisms and their interaction with their hosts. Chief Editor Yousef Abu Kwaik, University of Louisville is supported by an outstanding Editorial Board of international experts. This multidisciplinary open-access journal is at the forefront of disseminating and communicating scientific knowledge and impactful discoveries to researchers, academics, clinicians and the public worldwide.
Frontiers in Cellular and Infection Microbiology includes research on bacteria, fungi, parasites, viruses, endosymbionts, prions and all microbial pathogens as well as the microbiota and its effect on health and disease in various hosts. The research approaches include molecular microbiology, cellular microbiology, gene regulation, proteomics, signal transduction, pathogenic evolution, genomics, structural biology, and virulence factors as well as model hosts. Areas of research to counteract infectious agents by the host include the host innate and adaptive immune responses as well as metabolic restrictions to various pathogenic microorganisms, vaccine design and development against various pathogenic microorganisms, and the mechanisms of antibiotic resistance and its countermeasures.
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号
