Stepwise Post‐glycosylation Modification of Sugar Moieties in Kanamycin Biosynthesis

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.

Biosynthesis of cyclitols

“…23). The sugar moieties are further modied to produce matured kanamycins [105][106][107] and gentamicins. 103,[108][109][110][111][112][113][114][115][116][117] 3.4.3 Biosynthesis of hygromycin B.…”

“…23). The sugar moieties are further modified to produce matured kanamycins 105–107 and gentamicins. 103,108–117…”

Facile and selective N-alkylation of gentamicin antibiotics via chemoenzymatic synthesis

“…S2 †) and reactions with each of the AGAs were incubated for 24 hours and analysed by high-performance anion exchange chromatography with integrated pulsed amperometric detection (HPAE-IPAD). The aldehyde products formed were reported to be unstable 30,33 and hence an external product standard was not available for quantification. Thus, deamination was monitored by a combination of relative product area and substrate depletion compared to an external standard (Table 1 and ESI Fig.…”

Crystal structure of BtrK, a decarboxylase involved in the (S)-4-amino-2-hydroxybutyrate (AHBA) formation during butirosin biosynthesis

“…Most aminoglycosides have a 2deoxystreptamine (2-DOS) moiety as an aglycone, with different amino-sugars attached to the carbons 4 and 5 or 4 and 6 such as in kanamycin, gentamicin, and neomycin [8]. In recent years, there were great advances in the understanding of biosyntheses and in the enzymology of several biosynthetic steps from aminoglycosides, particularly those 2-DOS-containing molecules [9][10][11][12][13][14][15][16].…”