Source of methylmalonyl-coenzyme A for erythromycin synthesis: methylmalonyl-coenzyme A mutase from Streptomyces erythreus.
AUTOR(ES)
Hunaiti, A A
RESUMO
Streptomyces erythreus produces erythromycin, presumably from methylmalonyl-coenzyme A (CoA), which could be generated by the isomerization of succinyl-CoA. In S. erythreus cultures, [1,4-14C,2,3-3H]succinate was incorporated into erythromycin with a doubling of the 3H/14C ratio. This result is consistent with the hypothesis that succinyl-CoA is isomerized to methylmalonyl-CoA before incorporation into the macrocyclic lactone of erythromycin. The presence of methylmalonyl-CoA mutase, which catalyzes this isomerization, was demonstrated in cell-free extracts prepared from this organism. Consistent with the suggested role for this enzyme, methylmalonyl-CoA mutase activity increased over 12-fold at the time of the most rapid antibiotic production, and the activity level drastically declined when the antibiotic production ceased. The mutase was partially purified from this organism with DEAE-cellulose, ammonium sulfate precipitation, and affinity chromatography on a B12-coenzyme Sepharose column. The enzyme was stimulated 2.5-fold by the addition of B12-coenzyme. The enzyme showed a typical Michaelis-Menten type substrate saturation patterns, with KmS of 0.31 mM and 0.09 microM for methylmalonyl-CoA and B12-coenzyme, respectively, and a V of 0.5 mumol/min per mg. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed a major band with a molecular weight of 63,000. The properties of this enzyme appear to be fairly similar to those of the mutase previously obtained from other sources.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=185468Documentos Relacionados
- Cloning, sequencing, and expression of the gene encoding methylmalonyl-coenzyme A mutase from Streptomyces cinnamonensis.
- Genetic analysis of erythromycin production in Streptomyces erythreus.
- Metabolism of methylmalonic acid in rats. Is methylmalonyl-coenzyme a racemase deficiency symptomatic in man?
- Evidence for a sex factor in Streptomyces erythreus.
- Expression of the sodium ion pump methylmalonyl-coenzyme A-decarboxylase from Veillonella parvula and of mutated enzyme specimens in Escherichia coli.