AknT is an activating protein for the glycosyltransferase AknS in L-aminodeoxysugar transfer to the aglycone of aclacinomycin A.
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.
Lu
Wei
W
Department of Biological Chemistry and Molecular Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Leimkuhler
Catherine
C
Gatto
Gregory J
GJ
Kruger
Ryan G
RG
Oberthür
Markus
M
Kahne
Daniel
D
Walsh
Christopher T
CT
D015250:Aclarubicin / Q000737:chemistry / Q000378:metabolism; D018943:Anthracyclines / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004187:Disaccharides / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors; D006027:Glycosides / Q000737:chemistry / Q000378:metabolism*; D006031:Glycosylation; D016695:Glycosyltransferases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D009279:Naphthacenes / Q000737:chemistry / Q000378:metabolism; D009702:Nucleoside Diphosphate Sugars / Q000378:metabolism; D011485:Protein Binding; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism
D018943:Anthracyclines; D001426:Bacterial Proteins; D004187:Disaccharides; D006027:Glycosides; D009279:Naphthacenes; D009702:Nucleoside Diphosphate Sugars; C100183:thymidine diphosphate sugars; C027832:aklavinone; D015250:Aclarubicin; D016695:Glycosyltransferases