期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1999
卷号：96
期号：23
页码：13097-13102
DOI：10.1073/pnas.96.23.13097
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The SQD1 enzyme is believed to be involved in the biosynthesis of the sulfoquinovosyl headgroup of plant sulfolipids, catalyzing the transfer of SO3- to UDP-glucose. We have determined the structure of the complex of SQD1 from Arabidopsis thaliana with NAD+ and the putative substrate UDP-glucose at 1.6-A resolution. Both bound ligands are completely buried within the binding cleft, along with an internal solvent cavity which is the likely binding site for the, as yet, unidentified sulfur-donor substrate. SQD1 is a member of the short-chain dehydrogenase/reductase (SDR) family of enzymes, and its structure shows a conservation of the SDR catalytic residues. Among several highly conserved catalytic residues, Thr-145 forms unusually short hydrogen bonds with both susceptible hydroxyls of UDP-glucose. A His side chain may also be catalytically important in the sulfonation.
