Abstract
In type II polyketide synthases (PKSs), the ketosynthase-chain length factor (KS-CLF) complex catalyzes polyketide chain elongation with the acyl carrier protein (ACP). Highly reducing type II PKSs, represented by IgaPKS, produce polyene structures instead of the well-known aromatic skeletons. Here, we report the crystal structures of the Iga11-Iga12 (KS-CLF) heterodimer and the covalently cross-linked Iga10=Iga11-Iga12 (ACP=KS-CLF) tripartite complex. The latter structure revealed the molecular basis of the interaction between Iga10 and Iga11-Iga12, which differs from that between the ACP and KS of Escherichia coli fatty acid synthase. Furthermore, the reaction pocket structure and site-directed mutagenesis revealed that the negative charge of Asp 113 of Iga11 prevents further condensation using a β-ketoacyl product as a substrate, which distinguishes IgaPKS from typical type II PKSs. This work will facilitate the future rational design of PKSs.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Acyl Carrier Protein / chemistry*
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Acyl Carrier Protein / genetics
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Acyl Carrier Protein / metabolism
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Biocatalysis
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Catalytic Domain
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Cloning, Molecular
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Crystallography, X-Ray
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Escherichia coli / enzymology*
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Escherichia coli / genetics
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Escherichia coli Proteins / chemistry*
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Escherichia coli Proteins / genetics
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Escherichia coli Proteins / metabolism
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Fatty Acid Synthases / chemistry*
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Fatty Acid Synthases / genetics
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Fatty Acid Synthases / metabolism
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Gene Expression
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Genetic Vectors / chemistry
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Genetic Vectors / metabolism
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Models, Molecular
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Mutagenesis, Site-Directed
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Polyketide Synthases / chemistry*
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Polyketide Synthases / genetics
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Polyketide Synthases / metabolism
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Polyketides / chemistry*
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Polyketides / metabolism
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Protein Binding
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Protein Conformation, alpha-Helical
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Protein Conformation, beta-Strand
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Protein Interaction Domains and Motifs
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Protein Multimerization
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Streptomyces / enzymology
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Streptomyces / genetics
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Substrate Specificity
Substances
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Acyl Carrier Protein
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Escherichia coli Proteins
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Polyketides
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Recombinant Proteins
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Polyketide Synthases
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Fatty Acid Synthases