earticle

영어

FK506 is a 23-membered polyketide macrolide with immunosuppressant activity produced by
Streptomyces species. The production of FK506 in Streptomyces clavuligerus CKD1119 (KCTC
10561BP) was improved by enhancing the supply of biosynthetic precursors. FK506 production by S. clavuligerus CKD1119 was improved approximately 2.5-fold (15 mg/l) through the supplementation of 10 mM methyl oleate, which is the probable source of acyl-CoAs, in R2YE medium. When the level of FK506 production reached its maximum, the intracellular concentration of methylmalonyl- CoA in S. clavuligerus CKD1119 supplemented with methyl oleate was 12.5 times higher than that of the unsupplemented strain, suggesting that an increased methylmalonyl-CoA level caused the highlevel production of FK506. The following three pathways for the production of (2S)-methylmalonyl- CoA were evaluated to identify the effective precursor supply pathway that can support the high production of FK506 in S. clavuligerus CKD1119: propionyl-CoA carboxylase, methylmalonyl-CoA mutase (MCM), and malonyl/methylmalonyl-CoA ligase. Of the three pathways examined, the MCM pathway supported the highest levels of FK506 production. The expression of MCM in S. clavuligerus
CKD1119 led to a 3-fold and 1.5-fold increase in the methylmalonyl-CoA pool and FK506
production, respectively. Supplementing the culture broth of S. clavuligerus CKD1119 expressing
MCM with methyl oleate resulted in an additional 2-fold increase in the FK506 titer (17.8 mg/l).
Overall, these results show that the methylmalonyl-CoA supply is a limiting factor for FK506
biosynthesis, and among the three pathways analyzed, the MCM pathway is the most effective
precursor supply pathway supporting the highest titer of FK506 in S. clavuligerus CKD1119.