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Characterization of an Unprecedented Hybrid Pteridine‐Nonribosomal Peptide Synthetase‐Like Biosynthetic Gene Cluster
Author(s) -
Perez Corey E,
Park Hyun Bong,
Barber Karl W,
Rinehart Jesse,
Crawford Jason M
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.766.19
Subject(s) - biology , photorhabdus luminescens , nonribosomal peptide , photorhabdus , biochemistry , biogenesis , polyketide synthase , gene , biosynthesis , polyketide
The entomopathogen Photorhabdus luminescens is mutualistically associated with nematodes of the genus Heterohabditis while pathogenically associated with the nematode's larval prey. Upon invasion of an insect larva and exposure to its haemocoel, the nematode regurgitates P. luminescens . In this environment, an array of cellular processes are activated ultimately producing a plethora of small molecule metabolites that serve as antimicrobials, immunosuppressants, and cellular signals, amongst other functions. Given this nature, P. luminescens serves as an ideal source for the discovery of novel, bioactive small molecules as well as intriguing biochemistry. Utilizing genome synteny analysis, a technique capable of identifying atypical biosynthetic gene clusters that have been integrated into their host genomes via horizontal gene transfer, we identified a silent and previously uncharacterized biosynthetic pathway in P. luminescens that contains an unprecedented fusion of pteridine, pyruvate dehydrogenase‐like, and nonribosomal peptide synthetase (NRPS) biosynthetic machineries. Through the application of pathway‐targeted metabolomic analysis, a small family of metabolites, which we termed the “pepteridines,” were identified and structurally characterized. These molecules consist of a tetrahydropterin core functionalized with an acyl appendage at the N5 position. Through genetics, we further identified the individual genetic determinants for pepteridine biosynthesis. Seeking to better understand the coupling of the tetrahydropterin with its acyl substituent, a series of in vitro biochemical reactions were performed to assess the substrate scope of the atypical condensation domain present in the biosynthetic pathway. The resulting condensed metabolites demonstrate in vitro radical scavenging activity. And, utilizing a P. luminescens knockout strain, we demonstrated that the pathway serves to protect against oxidative stress. The pepteridines, as the first reported example of metabolites synthesized by a hybrid NRPS‐pteridine pathway, enhance our understanding of the combinatorial biosynthetic potential available in microbes. Support or Funding Information National Cancer Institute Grant (1DP2‐CA186575)National Institute of General Medical Sciences Grant (R00‐GM097096)Searle Scholars Program Grant (13‐SSP‐210) CEP was supported in part by a National Institutes of Health Chemistry Biology Interface Training Grant (5T32GM067543‐12)