Roles of the synergistic reductive O-methyltransferase GilM and of O-methyltransferase GilMT in the gilvocarcin biosynthetic pathway.
Two enzymes of the gilvocarcin biosynthetic pathway, GilMT and GilM, with unclear functions were investigated by in vitro studies using purified, recombinant enzymes along with synthetically prepared intermediates. The studies revealed GilMT as a typical S-adenosylmethionine (SAM) dependent O-methyltransferase, but GilM was identified as a pivotal enzyme in the pathway that exhibits dual functionality in that it catalyzes a reduction of a quinone intermediate to a hydroquinone, which goes hand-in-hand with a stabilizing O-methylation and a hemiacetal formation. GilM mediates its reductive catalysis through the aid of GilR that provides FADH(2) for the GilM reaction, through which FAD is regenerated for the next catalytic cycle. This unusual synergy eventually completes the biosynthesis of the polyketide-derived defuco-gilvocarcin chromphore.
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536-0596, United States.
Nidhi
N
Tibrewal
Theresa E
TE
Downey
Steven G
SG
Van Lanen
Ehesan
E
Ul Sharif
George A
GA
O'Doherty
Jürgen
J
Rohr
D000903:Antibiotics, Antineoplastic / Q000737:chemistry / Q000378:metabolism*; D003374:Coumarins / Q000737:chemistry / Q000378:metabolism*; D006027:Glycosides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000378:metabolism; D013302:Streptomyces / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
D000903:Antibiotics, Antineoplastic; D003374:Coumarins; D006027:Glycosides; D011994:Recombinant Proteins; C031781:gilvocarcin V; D012436:S-Adenosylmethionine; D008780:Methyltransferases