A rhodanese-like protein is highly overrepresented in the mutant S. clavuligerus oppA2::aph: effect on holomycin and other secondary metabolites production.
Bottom Line: Whereas total thiosulfate sulfurtransferase activity in cell extracts was not affected by the rhlA deletion, growth, cephamycin C and clavulanic acid production were impaired in the rhlA mutants.While growth on thiosulfate as the sole sulfur source was particularly low the volumetric and specific antibiotic production of the three antibiotics increased in all the strains in the presence of thiosulfate.This stimulatory effect of thiosulfate on antibiotic production was confirmed by addition of thiosulfate to pre-grown cells and appears to be a general effect of thiosulfate on oxidative stress as was also evident in the production of staurosporin by S. clavuligerus.
Affiliation: Área de Microbiología, Facultad de Ciencias Biológicas y Ambientales, Universidad de León, 24071 León, Spain.Show MeSH
Mentions: The rhlA gene is expressed in S. clavuligerus ATCC 27064 at 37 and 60 h of culture as detected by RT‐PCR experiments (Fig. 3D). In order to know if rhlA encodes a rhodanese‐like enzyme with thiosulfate sulfurtransferase activity, the enzyme was measured in S. clavuligerus ATCC 27064, S. clavuligerus oppA2::aph and their respective rhlA‐deleted mutants. Cultures were grown in SA medium and the enzyme activity was measured in cell extracts of 37 and 60 h of culture. Two compounds, thiosulfate and 3‐mercaptopyruvate, were used as substrates for the enzyme, giving relatively similar specific activities (1.16 ± 0.33 mUnits versus 0.87 ± 0.20 mUnits µg−1 protein respectively), with an activity slightly higher at 37 h than at 60 h. The results indicate that the rhlA deletion has no effect on the total thiosulfate sulfurtransferase activity (1.0 ± 0.24 in the wild‐type strain versus 1.04 ± 0.37 mUnits µg−1 protein in the rhlA‐deleted mutant), suggesting that the rhlA gene does not encode a thiosulfate sulfurtransferase.
Affiliation: Área de Microbiología, Facultad de Ciencias Biológicas y Ambientales, Universidad de León, 24071 León, Spain.