Stepwise Post‐glycosylation Modification of Sugar Moieties in Kanamycin Biosynthesis. (11th February 2021)

• Record Type: Journal Article
• Authors: Kudo, Fumitaka; Kitayama, Yukinobu; Miyanaga, Akimasa; Numakura, Mario; Eguchi, Tadashi
• Is Part Of: Chembiochem. Volume 22:Number 9(2021)
• Page Start: 1668
• Page End: 1675
• Publication Date: 2021-02-11
• Subjects: aminoglycoside antibiotics -- biosynthesis -- flavin-dependent dehydrogenases -- kanamycin -- non-heme iron oxygenases; Biochemistry -- Periodicals; Molecular biology -- Periodicals; Pharmaceutical chemistry -- Periodicals; 572
• DOI: 10.1002/cbic.202000839
• Languages: English
• ISSNs: 1439-4227

Abstract

Abstract: Kanamycin A is the major 2‐deoxystreptamine (2DOS)‐containing aminoglycoside antibiotic produced by Streptomyces kanamyceticus . The 2DOS moiety is linked with 6‐amino‐6‐deoxy‐d ‐glucose (6ADG) at O‐4 and 3‐amino‐3‐deoxy‐d ‐glucose at O‐6. Because the 6ADG moiety is derived from d ‐glucosamine (GlcN), deamination at C‐2 and introduction of C‐6‐NH2 are required in the biosynthesis. A dehydrogenase, KanQ, and an aminotransferase, KanB, are presumed to be responsible for the introduction of C‐6‐NH2, although the substrates have not been identified. Here, we examined the substrate specificity of KanQ to better understand the biosynthetic pathway. It was found that KanQ oxidized kanamycin C more efficiently than the 3′′‐deamino derivative. Furthermore, the substrate specificity of an oxygenase, KanJ, that is responsible for deamination at C‐2 of the GlcN moiety was examined, and the crystal structure of KanJ was determined. It was found that C‐6‐NH2 is important for substrate recognition by KanJ. Thus, the modification of the GlcN moiety occurs after pseudo‐trisaccharide formation, followed by the introduction of C‐6‐NH2 by KanQ/KanB and deamination at C‐2 by KanJ. Abstract : Step by step : A dehydrogenase KanQ oxidizes C‐6′‐OH of kanamycin C more efficiently than 3′′ ‐ deamino‐3′′ ‐ hydroxykanaymycin C or paromamine before introduction of C‐6′‐NH2, thus suggesting that the kanosamine moiety with C‐3′′‐NH2 is strictly recognized by KanQ. Furthermore, oxygenase KanJ recognizes C‐6′‐NH2 of the pseudo‐trisaccharide for deamination of C‐2′‐NH2 ; this suggests that these modifications mainly occur in a stepwise manner.