title: Analysis of the tetronomycin gene cluster: insights into the biosynthesis of a polyether tetronate antibiotic.
abstract: The biosynthetic gene cluster for tetronomycin (TMN), a polyether ionophoric antibiotic that contains four different types of ring, including the distinctive tetronic acid moiety, has been cloned from Streptomyces sp. NRRL11266. The sequenced tmn locus (113 234 bp) contains six modular polyketide synthase (PKS) genes and a further 27 open-reading frames. Based on sequence comparison to related biosynthetic gene clusters, the majority of these can be assigned a plausible role in TMN biosynthesis. The identity of the cluster, and the requirement for a number of individual genes, especially those hypothesised to contribute a glycerate unit to the formation of the tetronate ring, were confirmed by specific gene disruption. However, two large genes that are predicted to encode together a multifunctional PKS of a highly unusual type seem not to be involved in this pathway since deletion of one of them did not alter tetronomycin production. Unlike previously characterised polyether PKS systems, oxidative cyclisation appears to take place on the modular PKS rather than after transfer to a separate carrier protein, while tetronate ring formation and concomitant chain release share common mechanistic features with spirotetronate biosynthesis.
authors.affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Demydchuk
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Sun
authors.forename: Hui
authors.initials: H
authors.lastname: Hong
authors.forename: James
authors.initials: J
authors.lastname: Staunton
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Spencer
authors.forename: Peter F
authors.initials: PF
authors.lastname: Leadlay
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry; D002244:Carbon / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D003001:Cloning, Molecular; D004987:Ethers / Q000378:metabolism; D005663:Furans / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D009154:Mutation; D016366:Open Reading Frames / Q000235:genetics; D048630:Polyketide Synthases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D002352:Carrier Proteins; D004987:Ethers; D005663:Furans; D002244:Carbon; D048630:Polyketide Synthases; C034612:tetronomycin; C003422:tetronic acid