title: Expanding our understanding of sequence-function relationships of type II polyketide biosynthetic gene clusters: bioinformatics-guided identification of Frankiamicin A from Frankia sp. EAN1pec.
abstract: A large and rapidly increasing number of unstudied "orphan" natural product biosynthetic gene clusters are being uncovered in sequenced microbial genomes. An important goal of modern natural products research is to be able to accurately predict natural product structures and biosynthetic pathways from these gene cluster sequences. This requires both development of bioinformatic methods for global analysis of these gene clusters and experimental characterization of select products produced by gene clusters with divergent sequence characteristics. Here, we conduct global bioinformatic analysis of all available type II polyketide gene cluster sequences and identify a conserved set of gene clusters with unique ketosynthase α/β sequence characteristics in the genomes of Frankia species, a group of Actinobacteria with underexploited natural product biosynthetic potential. Through LC-MS profiling of extracts from several Frankia species grown under various conditions, we identified Frankia sp. EAN1pec as producing a compound with spectral characteristics consistent with the type II polyketide produced by this gene cluster. We isolated the compound, a pentangular polyketide which we named frankiamicin A, and elucidated its structure by NMR and labeled precursor feeding. We also propose biosynthetic and regulatory pathways for frankiamicin A based on comparative genomic analysis and literature precedent, and conduct bioactivity assays of the compound. Our findings provide new information linking this set of Frankia gene clusters with the compound they produce, and our approach has implications for accurate functional prediction of the many other type II polyketide clusters present in bacterial genomes.
authors.affiliation: Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, United States of America.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ogasawara
authors.affiliation: Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, United States of America.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Yackley
authors.affiliation: Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, United States of America.
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Greenberg
authors.affiliation: Department of Chemistry, New Mexico Institute of Mining and Technology, Socorro, New Mexico, United States of America; Department of Biology, New Mexico Institute of Mining and Technology, Socorro, New Mexico, United States of America.
authors.forename: Snezna
authors.initials: S
authors.lastname: Rogelj
authors.affiliation: Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico, United States of America; Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America; Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico, United States of America.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Melançon
mesh_terms: D000595:Amino Acid Sequence; D000880:Anthraquinones / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001688:Biological Products / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D019295:Computational Biology; D017124:Conserved Sequence; D040161:Frankia / Q000201:enzymology / Q000235:genetics*; D015870:Gene Expression; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family; D048630:Polyketide Synthases / Q000235:genetics* / Q000378:metabolism; D061065:Polyketides / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D000880:Anthraquinones; D001426:Bacterial Proteins; D001688:Biological Products; D061065:Polyketides; D048630:Polyketide Synthases
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