title: Molecular evidence for the coordination of nitrogen and carbon metabolisms, revealed by a study on the transcriptional regulation of the agl3EFG operon that encodes a putative carbohydrate transporter in Streptomyces coelicolor.
abstract: In the agl3EFGXYZ operon (SCO7167-SCO7162, abbreviated as agl3 operon) of Streptomyces coelicolor M145, agl3EFG genes encode a putative ABC-type carbohydrate transporter. The transcription of this operon has been proved to be repressed by Agl3R (SCO7168), a neighboring GntR-family regulator, and this repression can be released by growth on poor carbon sources. Here in this study, we prove that the transcription of agl3 operon is also directly repressed by GlnR, a central regulator governing the nitrogen metabolism in S. coelicolor. The electrophoretic mobility shift assay (EMSA) employing the agl3 promoter and mixtures of purified recombinant GlnR and Agl3R indicates that GlnR and Agl3R bind to different DNA sequences within the promoter region of agl3 operon, which is further confirmed by the DNase I footprinting assay. As Agl3R and GlnR have been demonstrated to sense the extracellular carbon and nitrogen supplies, respectively, it is hypothesized that the transcription of agl3 operon is stringently governed by the availabilities of extracellular carbon and nitrogen sources. Consistent with the hypothesis, the agl3 operon is further found to be derepressed only under the condition of poor carbon and rich nitrogen supplies, when both regulators are inactivated. It is believed that activation of the expression of agl3 operon may facilitate the absorption of extracellular carbohydrates to balance the ratio of intracellular carbon to nitrogen.
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Xu-Feng
authors.initials: XF
authors.lastname: Cen
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Jing-Zhi
authors.initials: JZ
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China; State Key Laboratory of Genetic Engineering, Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China; Shanghai-MOST Key Laboratory for Health and Disease Genomics, Chinese National Human Genome Center, Shanghai 201203, China; Department of Microbiology and Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong Special Administrative Region.
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Zhao
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China. Electronic address: ying.wang@tju.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China. Electronic address: jinwang@sibs.ac.cn.
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D050260:Carbohydrate Metabolism / Q000235:genetics; D002244:Carbon / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism*; D009876:Operon; D011401:Promoter Regions, Genetic; D048372:Streptomyces coelicolor / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C082451:GlnR protein, Streptomyces coelicolor; D015534:Trans-Activators; D002244:Carbon; D009584:Nitrogen
keywords: Agl3R; Carbon metabolism; GlnR; Nitrogen metabolism; Streptomyces coelicolor