title: Isolation and purification of a new kalimantacin/batumin-related polyketide antibiotic and elucidation of its biosynthesis gene cluster.
abstract: Kal/bat, a polyketide, isolated to high purity (>95%) is characterized by strong and selective antibacterial activity against Staphylococcus species (minimum inhibitory concentration, 0.05 microg/mL), and no resistance was observed in strains already resistant to commonly used antibiotics. The kal/bat biosynthesis gene cluster was determined to a 62 kb genomic region of Pseudomonas fluorescens BCCM_ID9359. The kal/bat gene cluster consists of 16 open reading frames (ORF), encoding a hybrid PKS-NRPS system, extended with trans-acting tailoring functions. A full model for kal/bat biosynthesis is postulated and experimentally tested by gene inactivation, structural confirmation (using NMR spectroscopy), and complementation. The structural and microbiological study of biosynthetic kal/bat analogs revealed the importance of the carbamoyl group and 17-keto group for antibacterial activity. The mechanism of self-resistance lies within the production of an inactive intermediate, which is activated in a one-step enzymatic oxidation upon export. The genetic basis and biochemical elucidation of the biosynthesis pathway of this antibiotic will facilitate rational engineering for the design of novel structures with improved activities. This makes it a promising new therapeutic option to cope with multidrug-resistant clinical infections.
authors.affiliation: Laboratory of Gene Technology, Katholieke Universiteit Leuven, Leuven B-3000, Belgium.
authors.forename: Wesley
authors.initials: W
authors.lastname: Mattheus
authors.forename: Ling-Jie
authors.initials: LJ
authors.lastname: Gao
authors.forename: Piet
authors.initials: P
authors.lastname: Herdewijn
authors.forename: Bart
authors.initials: B
authors.lastname: Landuyt
authors.forename: Jan
authors.initials: J
authors.lastname: Verhaegen
authors.forename: Joleen
authors.initials: J
authors.lastname: Masschelein
authors.forename: Guido
authors.initials: G
authors.lastname: Volckaert
authors.forename: Rob
authors.initials: R
authors.lastname: Lavigne
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000302:isolation & purification / Q000494:pharmacology; D001483:Base Sequence; D055785:Gene Knockdown Techniques; D005798:Genes, Bacterial; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D009930:Organic Chemicals / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism; D048630:Polyketide Synthases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D009930:Organic Chemicals; C088306:batumin; D048630:Polyketide Synthases; D006904:Hydroxymethylglutaryl-CoA Synthase; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase