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Abstract Heterologous expression of polyketide synthase (PKS) genes inEscherichia colihas enabled the production of various valuable natural and synthetic products. However, the limited availability of malonyl-CoA (M-CoA) inE. coliremains a substantial impediment to high-titer polyketide production. Here we address this limitation by disrupting the native M-CoA biosynthetic pathway and introducing an orthogonal pathway comprising a malonate transporter and M-CoA ligase, enabling efficient M-CoA biosynthesis under malonate supplementation. This approach substantially increases M-CoA levels, enhancing fatty acid and polyketide titers while reducing the promiscuous activity of PKSs toward undesired acyl-CoA substrates. Subsequent adaptive laboratory evolution of these strains provides insights into M-CoA regulation and identifies mutations that further boost M-CoA and polyketide production. This strategy improvesE. colias a host for polyketide biosynthesis and advances understanding of M-CoA metabolism in microbial systems.
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Giant polyketide synthase enzymes in the biosynthesis of giant marine polyether toxins
Prymnesium parvumare harmful haptophyte algae that cause massive environmental fish kills. Their polyketide polyether toxins, the prymnesins, are among the largest nonpolymeric compounds in nature and have biosynthetic origins that have remained enigmatic for more than 40 years. In this work, we report the “PKZILLAs,” massiveP. parvumpolyketide synthase (PKS) genes that have evaded previous detection. PKZILLA-1 and -2 encode giant protein products of 4.7 and 3.2 megadaltons that have 140 and 99 enzyme domains. Their predicted polyene product matches the proposed pre-prymnesin precursor of the 90-carbon–backbone A-type prymnesins. We further characterize the variant PKZILLA-B1, which is responsible for the shorter B-type analog prymnesin-B1, fromP. parvumRCC3426 and thus establish a general model of haptophyte polyether biosynthetic logic. This work expands expectations of genetic and enzymatic size limits in biology.
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- Award ID(s):
- 1831493
- PAR ID:
- 10535969
- Publisher / Repository:
- Science
- Date Published:
- Journal Name:
- Science
- Volume:
- 385
- Issue:
- 6709
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 671 to 678
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1126/science.ado3290
