|Hirayama A, Chu J, Goto E, Kudo F, Eguchi T
|NAD+-dependent dehydrogenase PctP and PLP-dependent aminotransferase PctCcatalyze the first post-glycosylation modification of sugar intermediate in pactamycin biosynthesis
|Aminocyclitol; Natural Product; Pactamycin; biosynthesis; enzymes
|The unique five-membered aminocyclitol core of the antitumor antibiotic pactamycin originates from D-glucose, so unprecedented enzymatic modifications of the sugar intermediate are involved in the biosynthesis. However, the order of the modification reactions remains elusive. Here, we examined the timing of introduction of an amino group into certain sugar-derived intermediates using recombinant enzymes that are encoded in the pactamycin biosynthesis gene cluster. We found that the NAD+-dependent alcohol dehydrogenase PctP and pyridoxal 5'-phosphate-dependent aminotransferase PctC convert N-acetyl-D- glucosaminyl-3-aminoacetophonone to 3'-amino-3'-deoxy-GlcNAc-3AAP. Further, GlcNAc-3-aminophenyl-β-oxopropanoic acid ethyl ester was converted to the corresponding 3'-amino-derivative. However, PctP did not oxidize most tested D- glucose derivatives including UDP-GlcNAc. Thus, modification of the GlcNAc moiety in pactamycin biosynthesis appears to occur after the glycosylation of aniline derivatives.