Modolo Luzia V, Li Lenong, Pan Haiyun, Blount Jack W, Dixon Richard A, Wang Xiaoqiang
Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA.
J Mol Biol. 2009 Oct 9;392(5):1292-302. doi: 10.1016/j.jmb.2009.08.017. Epub 2009 Aug 13.
The glycosyltransferase UGT78G1 from Medicago truncatula catalyzes the glycosylation of various (iso)flavonoids such as the flavonols kaempferol and myricetin, the isoflavone formononetin, and the anthocyanidins pelargonidin and cyanidin. It also catalyzes a reverse reaction to remove the sugar moiety from glycosides. The structures of UGT78G1 bound with uridine diphosphate or with both uridine diphosphate and myricetin were determined at 2.1 A resolution, revealing detailed interactions between the enzyme and substrates/products and suggesting a distinct binding mode for the acceptor/product. Comparative structural analysis and mutagenesis identify glutamate 192 as a key amino acid for the reverse reaction. This information provides a basis for enzyme engineering to manipulate substrate specificity and to design effective biocatalysts with glycosylation and/or deglycosylation activity.
来自蒺藜苜蓿的糖基转移酶UGT78G1催化多种（异）黄酮类化合物的糖基化反应，这些化合物包括黄酮醇山奈酚和杨梅素、异黄酮芒柄花素以及花青素天竺葵素和矢车菊素。它还催化逆反应，从糖苷中去除糖部分。以2.1埃的分辨率确定了与尿苷二磷酸结合或与尿苷二磷酸和杨梅素两者结合的UGT78G1的结构，揭示了酶与底物/产物之间的详细相互作用，并暗示了受体/产物的独特结合模式。比较结构分析和诱变确定谷氨酸192是逆反应的关键氨基酸。这些信息为酶工程提供了基础，以操纵底物特异性并设计具有糖基化和/或去糖基化活性的有效生物催化剂。
