Abstract
The metabolic flux of fatty acyl-CoAs determines lipopeptide biosynthesis efficiency, because acyl donor competition often occurs from polyketide biosynthesis and homologous pathways. We used A40926B0 as a model to investigate this mechanism. The lipopeptide A40926B0 with a fatty acyl group is the active precursor of dalbavancin, which is considered as a new lipoglycopeptide antibiotic. The biosynthetic pathway of fatty acyl-CoAs in the A40926B0 producer Nonomuraea gerenzanensis L70 was efficiently engineered using endogenous replicon CRISPR (erCRISPR). A polyketide pathway and straight-chain fatty acid biosynthesis were identified as major competitors in the malonyl-CoA pool. Therefore, we modified both pathways to concentrate acyl donors for the production of the desired compound. Combined with multiple engineering approaches, including blockage of an acetylation side reaction, overexpression of acetyl-CoA carboxylase, duplication of the dbv gene cluster and optimization of the fermentation parameters, the final strain produced 702.4 mg l-1 of A40926B0, a 2.66-fold increase, and the ratio was increased from 36.2% to 81.5%. Additionally, an efficient erCRISPR-Cas9 editing system based on an endogenous replicon was specifically developed for L70, which increased conjugation efficiency by 660% and gene-editing efficiency was up to 90%. Our strategy of redirecting acyl donor metabolic flux can be widely adopted for the metabolic engineering of lipopeptide biosynthesis.