title: Alternative method for site-directed mutagenesis of complex polyketide synthase in Streptomyces albus JA3453.
abstract: Sequence analysis of oxazolomycin (OZM) biosynthetic gene cluster from Streptomyces albus JA3453 revealed a gene, ozmH, encoding a hybrid polyketide and non-ribosomal peptide enzyme. Tandem ketosynthase (KS) domains (KS 10-1 and KS 10-2) were characterized and they show significant homology with known KSs. Using an alternative method that involves RecA-mediated homologous recombination, the negative selection marker sacB gene, and temperature-sensitive replications, site-directed mutagenesis of the catalytic triad amino acid cysteines were carried out in each of the tandem KS domains to test the function they play in OZM biosynthesis. HPLC-mass spectrometry analysis of the resulting mutant strains showed that KS 10-2 is essential for OZM biosynthesis but KS 10-1 is not indispensable and might serve as a "redundant" domain. These results confirmed the existence of an "extra domain" in complex polyketide synthase.
authors.affiliation: Laboratory of Microbial Metabolism and College of Life Sciences and Biotechnology, Shanghai Jiaotong University, Shanghai 200030, China.
authors.forename: Danfeng
authors.initials: D
authors.lastname: Song
authors.forename: Jane
authors.initials: J
authors.lastname: Coughlin
authors.forename: Jianhua
authors.initials: J
authors.lastname: Ju
authors.forename: Xiufen
authors.initials: X
authors.lastname: Zhou
authors.forename: Ben
authors.initials: B
authors.lastname: Shen
authors.forename: Chunhua
authors.initials: C
authors.lastname: Zhao
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
mesh_terms: D004789:Enzyme Activation; D004795:Enzyme Stability; D016297:Mutagenesis, Site-Directed / Q000379:methods*; D048630:Polyketide Synthases / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D015202:Protein Engineering / Q000379:methods*; D013302:Streptomyces / Q000145:classification / Q000201:enzymology* / Q000235:genetics*; D013329:Structure-Activity Relationship
chemical_list: D048630:Polyketide Synthases