AknT Is an Activating Protein for the Glycosyltransferase AknS in L-aminodeoxysugar Transfer to the Aglycone of Aclacinomycin A

Chem Biol. 2005 May;12(5):527-34. doi: 10.1016/j.chembiol.2005.02.016.

Abstract

During biosynthesis of the anthracycline antitumor agents daunomycin, adriamycin, and aclacinomycin, the polyketide-derived tetracyclic aglycone is enzymatically glycosylated at the C7-OH by dedicated glycosyltransferases (Gtfs) that transfer L-2,3,6-trideoxy-3-aminohexoses. In aclacinomycins, the first deoxyhexose is predicted to be transferred via AknS action, then subjected to further elongation to a trisaccharide by the subsequent Gtf, AknK. We report here that purified AknS has very low activity in the absence of the adjacently encoded AknT; however, at a 3:1 ratio, AknT stimulates AknS k(cat) by 40-fold up to 0.22 min(-1) for transfer of L-2-deoxyfucose (2-dF) to the aglycone aklavinone. It is likely that several other Gtfs that glycosylate polyketide aglycones also act as two-component catalytic systems. Incubations of purified AknS/AknT/AknK with two aglycones and two dTDP-2-deoxyhexoses produced previously uncharacterized anthracycline disaccharides.

Publication types

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

MeSH terms

  • Aclarubicin / chemistry
  • Aclarubicin / metabolism
  • Anthracyclines / chemistry
  • Anthracyclines / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / isolation & purification
  • Bacterial Proteins / metabolism*
  • Disaccharides / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Genetic Vectors
  • Glycosides / chemistry
  • Glycosides / metabolism*
  • Glycosylation
  • Glycosyltransferases / genetics
  • Glycosyltransferases / isolation & purification
  • Glycosyltransferases / metabolism*
  • Naphthacenes / chemistry
  • Naphthacenes / metabolism
  • Nucleoside Diphosphate Sugars / metabolism
  • Protein Binding
  • Streptomyces / genetics
  • Streptomyces / metabolism

Substances

  • Anthracyclines
  • Bacterial Proteins
  • Disaccharides
  • Glycosides
  • Naphthacenes
  • Nucleoside Diphosphate Sugars
  • thymidine diphosphate sugars
  • aklavinone
  • Aclarubicin
  • Glycosyltransferases