Enhanced salinomycin production by adjusting the supply of polyketide extender units in Streptomyces albus

• Published in: Metabolic engineering 2016-05, Vol.35, p.129-137
• Main Authors: Lu, Chenyang, Zhang, Xiaojie, Jiang, Ming, Bai, Linquan
• Format: Article
• Language: English
• Subjects: Acyl Coenzyme A - genetics; Acyl Coenzyme A - metabolism; Acyl-CoA Dehydrogenases - biosynthesis; Acyl-CoA Dehydrogenases - genetics; Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Crotonyl-CoA reductase; Extender unit; Genome; Metabolic Engineering; Polyketide; Polyketide Synthases - biosynthesis; Polyketide Synthases - genetics; Polyketides - metabolism; Pyrans - metabolism; Salinomycin; Streptomyces - genetics; Streptomyces - metabolism; Streptomyces albus
• ISSN: 1096-7176; 1096-7184
• DOI: 10.1016/j.ymben.2016.02.012

The anticoccidial salinomycin is a polyketide produced by Streptomyces albus and requires malonyl-CoAs, methylmalonyl-CoAs, and ethylmalonyl-CoAs for the backbone assembly. Genome sequencing of S. albus DSM 41398 revealed a high percentage of genes involved in lipid metabolism, supporting the high salinomycin yield in oil-rich media. Seven PKS/PKS-NRPS gene clusters in the genome were found to be actively transcribed and had been individually deleted, which resulted in significantly improved salinomycin production. However, a combined deletion of PKS-NRPS-2 and PKS-6 showed no further improvement. Whereas the concentrations of malonyl-CoA and methylmalonyl-CoA were increased, the concentration of ethylmalonyl-CoA remained low in the mutants. An endogenous crotonyl-CoA reductase gene (ccr) was overexpressed in the ΔPKS-NRPS-2/ΔPKS-6 mutant, resulting in improved production. Combination of cluster deletions and over-expression of ccr gene led to an overall titer improvement of salinomycin from 0.60 to 6.60g/L. This engineering strategy can be implemented for various natural polyketides production. •Streptomyces albus genome explained high salinomycin yield in oil-rich medium.•Quantitation of acyl-CoA esters identified limiting factors and engineered targets.•Cluster deletions and ethylmalonyl-CoA over-expression improved salinomycin titer.