Elucidation of the di-c-glycosylation steps during biosynthesis of the antitumor antibiotic, kidamycin

Abstract

Kidamycins belong to the pluramycin family of antitumor antibiotics that contain di-C-glycosylated angucycline. Owing to its interesting biological activity, several synthetic derivatives of kidamycins are currently being developed. However, the synthesis of these complex structural compounds with unusual C-glycosylated residues is difficult. In the kidamycin-producing Streptomyces sp. W2061 strain, the genes encoding the biosynthetic enzymes responsible for the structural features of kidamycin were identified. Two glycosyltransferase-coding genes, kid7 and kid21, were found in the kidamycin biosynthetic gene cluster (BGC). Gene inactivation studies revealed that the subsequent glycosylation steps occurred in a sequential manner, in which Kid7 first attached N,N-dimethylvancosamine to the C10 position of angucycline aglycone, following which Kid21 transferred an anglosamine moiety to C8 of the C10-glycosylated angucycline. Therefore, this is the first report to reveal the sequential biosynthetic steps of the unique C-glycosylated amino-deoxyhexoses of kidamycin. Additionally, we confirmed that all three methyltransferases (Kid4, Kid9, and Kid24) present in this BGC were involved in the biosynthesis of these amino-deoxyhexoses, N,N-dimethylvancosamine and anglosamine. Aglycone compounds and the mono-C-glycosylated compound obtained in this process will be used as substrates for the development of synthetic derivatives in the future.

A unique dual acyltransferase system shared in the polyketide chain initiation of kidamycinone and rubiflavinone biosynthesis

“…We previously reported the kid BGC from Streptomyces sp. W2061 (Heo et al, 2022), which is similar in content and organization to the known hedamycin BGC (Bililign et al, 2004). We also confirmed that Kid19, a ketosynthase of type II PKS, is responsible for the biosynthesis of the angucycline core (Heo et al, 2022).…”

“…W2061 (Heo et al, 2022), which is similar in content and organization to the known hedamycin BGC (Bililign et al, 2004). We also confirmed that Kid19, a ketosynthase of type II PKS, is responsible for the biosynthesis of the angucycline core (Heo et al, 2022). In this study, we inactivated the type I PKS gene (kid13), which may be involved in the production of the aglycone side chain moiety.…”

“…However, the C15 methyl residues of 1 and 3 may originate from methylmalonyl-CoA because the AT2 domain of Kid14 has a methylmalonyl-CoA conserved motif, whereas the AT domain of HedU has a malonyl-CoA conserved motif (Figure 3). Additionally, we previously reported that all three methyltransferases in kid BGC are involved in the biosynthesis of amino sugars, such as N,N-dimethylvancosamine and angolosamine (Heo et al, 2022). Collectively, these results suggest that there is an important difference between 1 and hedamycin in side-chain biosynthesis.…”

“…Previously, the biosynthetic gene cluster (BGC) of 1 (kid) was identified from the Streptomyces sp. W2061 (Heo et al, 2022). Our findings revealed that the kid BGC has a gene composition similar to that of the hedamycin BGC.…”

“…The structures of the compounds were determined based on nuclear magnetic resonance (NMR) analysis (Supplementary Table S3). Those compounds (3-5) are identified based on a comparison of previously reported NMR data and molecular formula (Mabit et al, 2017;Heo et al, 2022).…”