Starter Unit Flexibility for Engineered Product Synthesis by the Nonreducing Polyketide Synthase PksA
| Autor: | Jesse W. Li, Anna L. Vagstad, Craig A. Townsend, Callie R. Huitt-Roehl, Eric A. Hill, Martina M. Adams |
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| Rok vydání: | 2015 |
| Předmět: |
Fatty Acid Synthases
Aflatoxin B1 Stereochemistry Gene Expression Naphthalenes Biochemistry Article Substrate Specificity Fungal Proteins chemistry.chemical_compound Polyketide Starter Biosynthesis Acetyl Coenzyme A Catalytic Domain Polyketide synthase Escherichia coli biology food and beverages General Medicine Recombinant Proteins Kinetics Aspergillus Metabolic Engineering chemistry Pyrones Polyketides biology.protein Molecular Medicine Primer (molecular biology) Polyketide Synthases Acyl group Polyketide synthesis |
| Zdroj: | ACS Chemical Biology. 10:1443-1449 |
| ISSN: | 1554-8937 1554-8929 |
| DOI: | 10.1021/acschembio.5b00005 |
| Popis: | Non-reducing polyketide synthases (NR-PKSs) are unique among PKSs in their domain structure, notably including a starter unit:acyl-carrier protein (ACP) transacylase (SAT) domain that selects an acyl group as the primer for biosynthesis, most commonly acetyl-CoA from central metabolism. This clan of mega-enzymes resembles fatty acid synthases (FASs) by both sharing their central chain elongation steps and their capacity for iterative catalysis. In this mode of synthesis, catalytic domains involved in chain extension exhibit substrate plasticity to accommodate growing chains as small as two carbons to 20 or more. PksA is the NR-PKS central to the biosynthesis of the mycotoxin aflatoxin B1 and whose SAT domain accepts an unusual hexanoyl starter from a dedicated yeast-like FAS. Explored in this paper is the ability of PksA to utilize a selection of potential starter units as substrates to initiate and sustain extension and cyclization to on-target, programmed polyketide synthesis. Most of these starter units were successfully accepted and properly processed by PksA to achieve biosynthesis of the predicted naphthopyrone product. Analysis of the on-target and derailment products revealed trends of tolerance by individual PksA domains to alternative starter units. In addition, natural and unnatural variants of the active site cysteine were examined and found to be capable of biosynthesis, suggesting possible direct loading of starter units onto the β-ketoacyl synthase (KS) domain. In light of the data assembled here, the predictable synthesis of un-natural products by NR-PKSs is more fully defined. |
| Databáze: | OpenAIRE |
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