Isolation and sequence analysis of polyketide synthase genes from the daunomycin-producing Streptomyces sp. strain C5

Abstract

(23,25). Only in the cases of the tetracenomycin (40) and actinorhodin (5,19,34,55) PKSs, however, have biochemical characterizations also been carried out. Thus, most of the information on type II PKSs is derived from the strong conservation of gene structure among the PKS genes (23,25) and cross-functionality of the components (5,26,34,41). We describe here the structure of a gene region from Streptomyces sp. strain C5 that putatively encodes daunomycin biosynthesis and show that it has a significantly different overall structure from other type II PKS gene regions. MATERUILS AND METHODSBacterial strains and media used. Streptomyces sp. strain C5 and mutants derived from it have been described previously (3,4). Streptomyces lividans TK24 (22), used as a recombinant host strain, was obtained from D. A. Hopwood. Streptomyces coelicolor mutants, described by Rudd and Hopwood (37), were obtained from H. G. Floss. Streptomyces galilaeus ATCC 31671, which lacks a functional polyketide reductase (PKR), has been described previously (5, 50).

Expression, Purification, and Characterization of AknX Anthrone Oxygenase, Which Is Involved in Aklavinone Biosynthesis in Streptomyces galilaeus

“…In genetic studies on anthracycline biosynthesis, similar small ORFs were identified in the biosynthetic gene clusters just upstream from the KS gene in S. peucetius (6), Streptomyces sp. strain C5 (20), Streptomyces nogalater (21), and S. galilaeus (4). Their homology with tcmH suggested that the encoded enzyme might catalyze the oxygenation of aklanonic acid anthrone to form aklanonic acid.…”

“…Such genes are not found in typical type II PKS gene clusters like that of actinorhodin (2). However, similar small ORFs exist in known anthracycline biosynthetic gene clusters such as dauG/dnrG in the daunorubicin/doxorubicin biosynthetic gene cluster (6,20), and snoaB in the nogalamycin biosynthesis gene cluster (21) (Fig. 2).…”

Crystal Structure of Aclacinomycin Methylesterase with Bound Product Analogues

“…Biosynthesis starts with the polyketide pathway, where the carbon chain is built up by repeated Claisen condensations from acyl and malonate carbonyl units by the large polyketide synthase complex (8). These condensation steps are followed by a final cyclization to give the aglycone polyketide skeleton (9). The cyclized product is then further modified by a series of tailoring enzymes leading to, for example, glycosylation, hydroxylation, methylester hydrolysis, and decarboxylation (10 -15).…”

In vivo and in vitro bioconversion of epsilon-rhodomycinone glycoside to doxorubicin: functions of DauP, DauK, and DoxA

“…1) are clinically important anthracycline chemotherapeutic agents (2, 11, 17), which are synthesized by a type II polyketide synthase (23,(42)(43)(44). The aglycone is formed by condensing nine extender units derived from malonyl coenzyme A onto a propionyl moiety to make a C 21 polyketide intermediate (21,23,(42)(43)(44)(45)50), which is reduced at C-9 from the carboxy terminus (43, 44), cyclized, and aromatized to form aklanonic acid (18,19,23,40,(42)(43)(44). Aklanonic acid is converted in four steps to ε-rhodomycinone (3,7,15,16,30,40,42,44), an intermediate that is accumulated in large quantities by most daunorubicin-producing strains (27,42,44,46).…”