The biosynthetic gene cluster for the antitumor rebeccamycin: characterization and generation of indolocarbazole derivatives.
Rebeccamycin, a halogenated natural product of the indolocarbazole family, is produced by Saccharothrix aerocolonigenes ATCC39243. Several rebeccamycin analogues, which target DNA topoisomerase I or II, have already entered clinical trials as anticancer drugs. Using as a probe an internal fragment of ngt, a Saccharothrix aerocolonigenes gene encoding an indolocarbazole N-glycosyltransferase, we isolated a DNA region that directed the biosynthesis of rebeccamycin when introduced into Streptomyces albus. Sequence analysis of 25.6 kb revealed genes for indolocarbazole core formation, halogenation, glycosylation, and sugar methylation, as well as a regulatory gene and two resistance/secretion genes. Heterologous expression of subsets of these genes resulted in production of deschloro-rebeccamycin, 4'-demethyldeschloro-rebeccamycin, and deschloro-rebeccamycin aglycone. The cloned genes should help to elucidate the molecular basis for indolocarbazole biosynthesis and set the stage for the generation of novel indolocarbazole analogues by genetic engineering.
Sánchez
César
C
Departamento de Biología Funcional e Instituto, Universitario de Oncología del Principado de Asturias, Universidad de Oviedo, 33006 Oviedo, Spain.
Butovich
Igor A
IA
Braña
Alfredo F
AF
Rohr
Jürgen
J
Méndez
Carmen
C
Salas
José A
JA
D000192:Actinomycetales / Q000201:enzymology; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D000970:Antineoplastic Agents; D002227:Carbazoles; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D016695:Glycosyltransferases / Q000235:genetics / Q000378:metabolism; D007211:Indoles; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D005810:Multigene Family; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000235:genetics
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000970:Antineoplastic Agents; D002227:Carbazoles; D007211:Indoles; C075954:indolo(3,2-b)carbazole; C053339:rebeccamycin; D016695:Glycosyltransferases