The G243D mutation (afsB mutation) in the principal sigma factor sigmaHrdB alters intracellular ppGpp level and antibiotic production in Streptomyces coelicolor A3(2).
Deficient antibiotic production in an afsB mutant, BH5, of Streptomyces coelicolor A3(2) was recently shown to be due to a mutation (G243D) in region 1.2 of the primary sigma factor sigma(HrdB). Here we show that intracellular ppGpp levels during growth, as well as after amino acid depletion, in the mutant BH5 are lower than those of the afsB(+) parent strain. The introduction of certain rifampicin resistance (rif) mutations, which bypassed the requirement of ppGpp for transcription of pathway-specific regulatory genes, actII-ORF4 and redD, for actinorhodin and undecylprodigiosin, respectively, completely restored antibiotic production by BH5. Antibiotic production was restored also by introduction of a new class of thiostrepton-resistance (tsp) mutations, which provoked aberrant accumulation of intracellular ppGpp. Abolition of ppGpp synthesis in the afsB tsp mutant Tsp33 again abolished antibiotic production. These results indicate that intracellular ppGpp level is finely tuned for successful triggering of antibiotic production in the wild-type strain, and that this fine tuning was absent from the afsB mutant BH5, resulting in a failure to initiate antibiotic production in this strain.
Wang
Guojun
G
National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan.
Tanaka
Yukinori
Y
National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan.
Ochi
Kozo
K
Hiroshima Institute of Technology, Department of Health Science, Faculty of Applied Information Science, Miyake 2-1-1, Saeki-ku, Hiroshima 731-5193, Japan.|National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan.
D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics*; D003227:Conjugation, Genetic; D004268:DNA-Binding Proteins / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D006159:Guanosine Tetraphosphate / Q000096:biosynthesis*; D008826:Microbial Sensitivity Tests; D009154:Mutation; D012329:RNA, Bacterial / Q000235:genetics; D012293:Rifampin; D012808:Sigma Factor / Q000235:genetics*; D048372:Streptomyces coelicolor / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012329:RNA, Bacterial; D012808:Sigma Factor; D014157:Transcription Factors; C066581:AfsR protein, Streptomyces coelicolor; C071941:HrdB protein, Streptomyces; D006159:Guanosine Tetraphosphate; D012293:Rifampin