title: NAD(+)-specific glutamate dehydrogenase (EC.1.4.1.2) in Streptomyces coelicolor; in vivo characterization and the implication for nutrient-dependent secondary metabolism.
abstract: While glutamate and glutamate-rich compounds are widely used for culturing Streptomyces sp., little is known regarding glutamate catabolism at molecular level. Noting the presence of two distinct putative glutamate dehydrogenases (GDH), we constructed knockout mutants of each gene with Streptomyces coelicolor M145 and examined the functionality related to antibiotic production. Out of the two, the sco2999 knockout (ΔgdhB, NAD(+)-specific) showed outstanding effects; it decreased the growth sevenfold but initiated the undecylprodigiosin (RED) production in complex Difco nutrient media which otherwise does not support the production from M145. With glucose supplementation, the growth difference by ΔgdhB disappeared but we could obtain significantly increased actinorhodin (ACT) and RED biosynthesis with the mutant by limiting the glucose content (0.5∼1.0 %, w/v). Complementing the gene to the knockout mutant inhibited the production, confirming its gene specificity. Along with the extended impacts on overall nitrogen metabolism based on the intracellular metabolite analysis and enzyme assays, GdhB and glutamate utilization were shown to interfere with N-acetylglucosamine metabolism and the activity of its associated global transcriptional regulator (DasR). Taken together, GdhB-subjected to the nutritional context-dependent regulation-is proposed as a key member of central nitrogen metabolism to control the secondary metabolism initiation in exploiting the organic nitrogen sources.
authors.affiliation: Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea. songhee@snu.ac.kr.
authors.forename: Songhee H
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Institute of Molecular Biology and Genetics, Seoul National University, Seoul, Republic of Korea. byungkim@snu.ac.kr.|School of Chemical and Biological Engineering, Institute of Bioengineering, Seoul National University, Seoul, Republic of Korea. byungkim@snu.ac.kr.
authors.forename: Byung-Gee
authors.initials: BG
authors.lastname: Kim
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000378:metabolism; D001426:Bacterial Proteins; D003470:Culture Media / Q000737:chemistry; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D005947:Glucose / Q000378:metabolism*; D005969:Glutamate Dehydrogenase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D011353:Prodigiosin / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000378:metabolism; D011485:Protein Binding; D064210:Secondary Metabolism; D048372:Streptomyces coelicolor / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003470:Culture Media; D009243:NAD; C047347:undecylprodigiosin; D005969:Glutamate Dehydrogenase; D005947:Glucose; D011353:Prodigiosin
keywords: DasR; Glucose; Glutamate dehydrogenase; N-acetylglucosamine; Secondary metabolism