title: Identification of two-component system AfsQ1/Q2 regulon and its cross-regulation with GlnR in Streptomyces coelicolor.
abstract: The two-component system AfsQ1/Q2 of Streptomyces coelicolor was identified in our previous work as a pleiotropic regulator for antibiotic biosynthesis and morphological differentiation under the condition of a minimal medium supplemented with 75 mM glutamate. In this work, we report the dissection of the mechanism underlying the function of AfsQ1/Q2 on antibiotic production and also the identification of the AfsQ1/Q2 regulon. The results showed that AfsQ1/Q2 stimulated antibiotic ACT, RED and CDA production directly through the pathway-specific activator genes actII-ORF4, redZ and cdaR respectively. In addition, expression of sigQ that encodes a sigma factor and is divergently transcribed from afsQ1 was also subject to direct regulation by AfsQ1/Q2. The precise AfsQ1 binding sites in the upstream regions of these target genes were determined by DNase I footprinting assays coupled with site-directed DNA mutagenesis. By computational prediction and functional analysis, at least 17 new AfsQ1 targets were identified, including pstS gene encoding a high-affinity phosphate-binding protein and two developmental genes whiD, bldM. For the AfsQ1/Q2 regulon, an AfsQ1 binding motif comprising the sequence GTnAC-n(6) -GTnAC has been defined. Interestingly, we found from electrophoretic mobility shift assays and transcriptional analysis that AfsQ1/Q2 can also function as a repressor for nitrogen assimilation, and AfsQ1 can compete with GlnR for the promoter regions of glnA and nirB, suggesting the cross-regulation between AfsQ1/Q2 and GlnR in nitrogen metabolism. These findings suggested that AfsQ1/Q2 is important not only for antibiotic biosynthesis but also in maintaining the metabolic homeostasis of nutrient utilization under the stress of high concentration of glutamate in S. coelicolor.
authors.affiliation: 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: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Mast
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.forename: Weiwen
authors.initials: W
authors.lastname: Zhang
authors.forename: Guoping
authors.initials: G
authors.lastname: Zhao
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wohlleben
authors.forename: Yinhua
authors.initials: Y
authors.lastname: Lu
authors.forename: Weihong
authors.initials: W
authors.lastname: Jiang
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018983:DNA Footprinting; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial; D018698:Glutamic Acid / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D011401:Promoter Regions, Genetic; D018085:Regulon / Q000235:genetics*; D048372:Streptomyces coelicolor / Q000235:genetics* / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C082451:GlnR protein, Streptomyces coelicolor; D015534:Trans-Activators; D014157:Transcription Factors; C498877:WhiD protein, Streptomyces coelicolor; D018698:Glutamic Acid; D003850:Deoxyribonuclease I; D009584:Nitrogen