Genetic and physiological characterization of rpoB mutations that activate antibiotic production in Streptomyces lividans.
Antibiotic production in Streptomyces lividans can be activated by introducing certain mutations (rif) into the rpoB gene that confer resistance to rifampicin. Working with the most typical (rif-17) mutant strain, KO-417, the rif-17 mutation was characterized. The rif-17 mutation was shown to be responsible for activating antibiotic production and for reducing the growth rate of strain KO-417, as demonstrated by gene-replacement experiments. Gene-expression analysis revealed that introduction of rif into S. lividans elevates expression of the pathway-specific regulatory gene actII-ORF4 to nearly the same level seen in Streptomyces coelicolor. The rif effect on antibiotic production was still evident in the genetic background of relC, indicating that the rif mutation can provoke its effect without depending on ppGpp. Accompanying the restoration of antibiotic production, rif mutants also exhibited a lower rate of RNA synthesis compared to the parental strain when grown in a nutritionally rich medium, suggesting that the mutant RNA polymerases may behave like 'stringent' RNA polymerases. These results indicate that the rif mutation can alter the gene-expression pattern independent of ppGpp. The impaired growth of strain KO-417 (rif-17) was largely restored by introducing the second rif mutation (rif-18) just adjacent to the rif-17 position. Proteome analysis using two-dimensional PAGE revealed that the rif mutant strain KO-418 (rif-17 rif-18) displayed a temporal burst of expression especially of two enzymes, glutamine synthetase (type II) and oxidoreductase, during the late growth phase.
Lai
Caixia
C
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan1.
Xu
Jun
J
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan1.
Tozawa
Yuzuru
Y
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan1.
Okamoto-Hosoya
Yoshiko
Y
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan1.
Yao
Xingsheng
X
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan1.
Ochi
Kozo
K
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan1.
D000596:Amino Acids / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D009154:Mutation; D010641:Phenotype; D012269:Ribosomal Proteins / Q000235:genetics; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism*
D000596:Amino Acids; D000900:Anti-Bacterial Agents; D012269:Ribosomal Proteins; C017721:casamino acids; C027624:ribosomal protein L11; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit