Rational Control of Polyketide Extender Units by Structure-Based Engineering of a Crotonyl-CoA Carboxylase/Reductase in Antimycin Biosynthesis

• Published in: Angewandte Chemie International Edition 2015-11, Vol.54 (45), p.13462-13465
• Main Authors: Zhang, Lihan, Mori, Takahiro, Zheng, Qingfei, Awakawa, Takayoshi, Yan, Yan, Liu, Wen, Abe, Ikuro
• Format: Article
• Language: English
• Subjects: Acyl-CoA Dehydrogenases - chemistry; Acyl-CoA Dehydrogenases - metabolism; Antimycin A - analogs & derivatives; Antimycin A - biosynthesis; Antimycin A - chemistry; Bearing; Biocatalysts; Bioengineering; Biosynthesis; Carbon; Carboxylation; Combinatorial analysis; crotonyl-CoA carboxylase/reductase; Crystal structure; Engineering; Molecular modelling; Mutation; Natural products; polyketides; Polyketides - chemistry; Protein Conformation; Protein Engineering; Reductase; Reductases; Site-directed mutagenesis; Strain; Substrates
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201506899

Bioengineering of natural product biosynthesis is a powerful approach to expand the structural diversity of bioactive molecules. However, in polyketide biosynthesis, the modification of polyketide extender units, which form the carbon skeletons, has remained challenging. Herein, we report the rational control of polyketide extender units by the structure‐based engineering of a crotonyl‐CoA carboxylase/reductase (CCR), in the biosynthesis of antimycin. Site‐directed mutagenesis of the CCR enzyme AntE, guided by the crystal structure solved at 1.5 Å resolution, expanded its substrate scope to afford indolylmethylmalonyl‐CoA by the V350G mutation. The mutant A182L selectively catalyzed carboxylation over the regular reduction. Furthermore, the combinatorial biosynthesis of heterocycle‐ and substituted arene‐bearing antimycins was achieved by an engineered Streptomyces strain bearing AntEV350G. These findings deepen our understanding of the molecular mechanisms of the CCRs, which will serve as versatile biocatalysts for the manipulation of building blocks, and set the stage for the rational design of polyketide biosynthesis. Extender unit engineering: The crotonyl‐CoA carboxylase/reductase AntE was engineered to catalyze the carboxylation of a variety of substrates. By introducing the engineered AntE into a host strain, unnatural antimycins bearing a heterocyclic or substituted arene extender unit were biosynthesized.