cb400691z_si_001.pdf (3.17 MB)
Tyrosine O‑Prenyltransferase SirD Catalyzes S‑, C‑, and N‑Prenylations on Tyrosine and Tryptophan Derivatives
journal contribution
posted on 2013-12-20, 00:00 authored by Jeffrey
D. Rudolf, C. Dale PoulterThe
tyrosine O-prenyltransferase SirD in Leptosphaeria
maculans catalyzes normal prenylation of the
hydroxyl group in tyrosine as the first committed step in the biosynthesis
of the phytotoxin sirodesmin PL. SirD also catalyzes normal N-prenylation of 4-aminophenylalanine and normal C-prenylation at C7 of tryptophan. In this study, we found
that 4-mercaptophenylalanine and several derivatives of tryptophan
are also substrates for prenylation by dimethylallyl diphosphate.
Incubation of SirD with 4-mercaptophenylalanine gave normal S-prenylated mercaptophenylalanine. We found that incubation
of the enzyme with tryptophan gave reverse prenylation at N1 in addition
to the previously reported normal prenylation at C7. 4-Methyltryptophan
also gave normal prenylation at C7 and reverse prenylation at N1,
whereas 4-methoxytryptophan gave normal and reverse prenylation at
C7, and 7-methyltryptophan gave normal prenylation at C6 and reverse
prenylation at N1. The ability of SirD to prenylate at three different
sites on the indole nucleus, with normal and reverse prenylation at
one of the sites, is similar to behavior seen for dimethylallyltryptophan
synthase. The multiple products produced by SirD suggests it and dimethylallyltryptophan
synthase use a dissociative electrophilic mechanism for alkylation
of amino acid substrates.