Open AccessCloning and characterization of polyketide synthase genes for jadomycin B biosynthesis in Streptomyces venezuelae ISP5230
Author(s) -
Lei Han,
Keqian Yang,
Eswar Ramalingam,
Roy H. Mosher,
L. C. Vining
Publication year - 1994
Publication title -
microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 179
eISSN - 1465-2080
pISSN - 1350-0872
DOI - 10.1099/13500872-140-12-3379
Subject(s) - biology , orfs , subcloning , polyketide , polyketide synthase , plasmid , streptomyces coelicolor , streptomyces , atp synthase , biosynthesis , open reading frame , gene , genetics , genomic dna , biochemistry , peptide sequence , bacteria
Hybridizing fragments in the genomic DNA of Streptomyces venezuelae ISP5230, which produces the jadomycin group of angucycline antibiotics, were detected by probing with actI DNA from Streptomyces coelicolor A3(2). The hybridizing regions were isolated from a 16.5 kb insert of S. venezuelae DNA recovered from a genomic library cloned in a lambda replacement vector. Subcloning and sequencing of a 4.8 kb segment of the insert, containing regions hybridizing to actIII as well as actI, identified five open reading frames (ORFs). The deduced polypeptide products of the ORFs closely resemble in sequence the components of streptomycete type-II polyketide synthases (PKSs): the ORF1 product corresponds to the ketoacyl synthase, and the ORF2 product to a polypeptide closely related to the ketoacyl synthase and involved in determining chain length; the ORF3 product matches the acyl carrier protein; ORF4 encodes a bifunctional cyclase/dehydrase; and ORF5 encodes a ketoreductase. Integration into the chromosomal DNA of a plasmid containing a segment of the ORF2-ORF4 region severely depressed jadomycin B biosynthesis; since the integrant showed no change in growth or spore pigmentation, the cloned PKS genes are presumed to encode enzymes in the pathway for jadomycin biosynthesis.