title: GlnR-Mediated Regulation of ectABCD Transcription Expands the Role of the GlnR Regulon to Osmotic Stress Management.
abstract: Ectoine and hydroxyectoine are excellent compatible solutes for bacteria to deal with environmental osmotic stress and temperature damages. The biosynthesis cluster of ectoine and hydroxyectoine is widespread among microorganisms, and its expression is activated by high salinity and temperature changes. So far, little is known about the mechanism of the regulation of the transcription of ect genes and only two MarR family regulators (EctR1 in methylobacteria and the EctR1-related regulator CosR in Vibrio cholerae) have been found to negatively regulate the expression of ect genes. Here, we characterize GlnR, the global regulator for nitrogen metabolism in actinomycetes, as a negative regulator for the transcription of ectoine/hydroxyectoine biosynthetic genes (ect operon) in Streptomyces coelicolor. The physiological role of this transcriptional repression by GlnR is proposed to protect the intracellular glutamate pool, which acts as a key nitrogen donor for both the nitrogen metabolism and the ectoine/hydroxyectoine biosynthesis.
  
  
  OBJECTIVE
  High salinity is deleterious, and cells must evolve sophisticated mechanisms to cope with this osmotic stress. Although production of ectoine and hydroxyectoine is one of the most frequently adopted strategies, the in-depth mechanism of regulation of their biosynthesis is less understood. So far, only two MarR family negative regulators, EctR1 and CosR, have been identified in methylobacteria and Vibrio, respectively. Here, our work demonstrates that GlnR, the global regulator for nitrogen metabolism, is a negative transcriptional regulator for ect genes in Streptomyces coelicolor. Moreover, a close relationship is found between nitrogen metabolism and osmotic resistance, and GlnR-mediated regulation of ect transcription is proposed to protect the intracellular glutamate pool. Meanwhile, the work reveals the multiple roles of GlnR in bacterial physiology.
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: ZhiHui
authors.initials: Z
authors.lastname: Shao
authors.affiliation: Key Laboratory of Medical Reprogramming Technology, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, China.
authors.forename: WanXin
authors.initials: W
authors.lastname: Deng
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: ShiYuan
authors.initials: S
authors.lastname: Li
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: JuanMei
authors.initials: J
authors.lastname: He
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: ShuangXi
authors.initials: S
authors.lastname: Ren
authors.affiliation: Key Laboratory of Medical Reprogramming Technology, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, China.
authors.forename: WeiRen
authors.initials: W
authors.lastname: Huang
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: YinHua
authors.initials: Y
authors.lastname: Lu
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China Key Laboratory of Medical Reprogramming Technology, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, China State Key Lab of Genetic Engineering & Center for Synthetic Biology, Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai, China Department of Microbiology and Li KaShing Institute of Health Sciences, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.
authors.forename: GuoPing
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Medical Reprogramming Technology, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, China caizhiming2000@163.com jinwang@sibs.ac.cn.
authors.forename: ZhiMing
authors.initials: Z
authors.lastname: Cai
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China Key Laboratory of Medical Reprogramming Technology, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, China caizhiming2000@163.com jinwang@sibs.ac.cn.
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
mesh_terms: D000599:Amino Acids, Diamino / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D005971:Glutamates / Q000378:metabolism; D009154:Mutation; D009997:Osmotic Pressure / Q000502:physiology*; D018085:Regulon / Q000502:physiology*; D048372:Streptomyces coelicolor / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D000599:Amino Acids, Diamino; D001426:Bacterial Proteins; C082451:GlnR protein, Streptomyces coelicolor; D005971:Glutamates; D015534:Trans-Activators; C121557:hydroxyectoine; C045628:ectoine