Characterization of Rhodosaminyl Transfer by the AknS/AknT Glycosylation Complex and Its Use in Reconstituting the Biosynthetic Pathway of Aclacinomycin A

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• 作者：Catherine Leimkuhler ; Micha Fridman ; Tania Lupoli ; Suzanne Walker ; Christopher T. Walsh ; Daniel Kahne
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：August 29, 2007
• 年：2007
• 卷：129
• 期：34
• 页码：10546 - 10550
• 全文大小：102K
• 年卷期：v.129,no.34(August 29, 2007)
• ISSN：1520-5126

文摘

The tetracyclic core of anthracycline natural products with antitumor activity such as aclacinomycinA are tailored during biosynthesis by regioselective glycosylation. We report the first synthesis of TDP-L-rhodosamine and demonstrate that the glycosyltransferase AknS transfers L-rhodosamine to the aglyconeto initiate construction of the side-chain trisaccharide. The partner protein AknT accelerates AknS turnoverrate for L-rhodosamine transfer by 200-fold. AknT does not affect the K_m but rather affects the k_cat. Usingthese data, we propose that AknT causes a conformational change in AknS that stabilizes the transitionstate and ultimately enhances transfer. When the subsequent glycosyltransferase AknK and its substrateTDP-L-fucose are also added to the aglycone, the disaccharide and low levels of a fully reconstitutedtrisaccharide form of aclacinomycin are observed.