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

J Am Chem Soc. 2007 Aug 29;129(34):10546-50. doi: 10.1021/ja072909o. Epub 2007 Aug 8.

Abstract

The tetracyclic core of anthracycline natural products with antitumor activity such as aclacinomycin A 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 aglycone to initiate construction of the side-chain trisaccharide. The partner protein AknT accelerates AknS turnover rate for L-rhodosamine transfer by 200-fold. AknT does not affect the Km but rather affects the kcat. Using these data, we propose that AknT causes a conformational change in AknS that stabilizes the transition state and ultimately enhances transfer. When the subsequent glycosyltransferase AknK and its substrate TDP-L-fucose are also added to the aglycone, the disaccharide and low levels of a fully reconstituted trisaccharide form of aclacinomycin are observed.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aclarubicin / biosynthesis*
  • Aclarubicin / chemistry
  • Aclarubicin / metabolism
  • Antineoplastic Agents / chemistry
  • Glycosylation
  • Glycosyltransferases / chemistry*
  • Glycosyltransferases / metabolism*
  • Hexosamines / metabolism*
  • Kinetics
  • Macrolides / chemistry*
  • Molecular Structure
  • Substrate Specificity

Substances

  • Antineoplastic Agents
  • Hexosamines
  • Macrolides
  • Aclarubicin
  • Glycosyltransferases