Abstract
Proteins belonging to the NTF2-like superfamily are present in the biosynthetic pathways of numerous polyketide natural products, such as anthracyclins and benzoisochromanequinones. Some have been found to be bona fide polyketide cyclases, but many of them have roles that are currently unknown. Here, the X-ray crystal structures of three NTF2-like proteins of unknown function are reported: those of ActVI-ORFA from Streptomyces coelicolor A3(2) and its homologs Caci_6494, a protein from an uncharacterized biosynthetic cluster in Catenulispora acidiphila, and Aln2 from Streptomyces sp. CM020, a protein in the biosynthetic pathway of alnumycin. The presence of a solvent-accessible cavity and the conservation of the His/Asp dyad that is characteristic of many polyketide cyclases suggest a potential enzymatic role for these enzymes in polyketide biosynthesis.
Keywords:
NTF2-like superfamily; actinorhodin; alnumycin; polyketide cyclases; secondary metabolism.
MeSH terms
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Actinobacteria / chemistry*
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Actinobacteria / enzymology
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Amino Acid Sequence
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Anthraquinones / chemistry
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Anthraquinones / metabolism
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Bacterial Proteins / chemistry*
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Binding Sites
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Cloning, Molecular
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Crystallography, X-Ray
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Escherichia coli / genetics
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Escherichia coli / 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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Multigene Family
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Naphthoquinones / chemistry
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Naphthoquinones / 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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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Streptomyces / chemistry*
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Streptomyces / enzymology
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Streptomyces coelicolor / chemistry*
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Streptomyces coelicolor / enzymology
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Substrate Specificity
Substances
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Anthraquinones
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Bacterial Proteins
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Naphthoquinones
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Polyketides
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Recombinant Proteins
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alnumycin
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actinorhodin