3wq4

Publication Abstract from PubMed

beta-Primeverosidase (PD) is a disaccharide-specific beta-glycosidase in tea leaves. This enzyme is involved in aroma formation during the manufacturing process of oolong tea and black tea. PD hydrolyzes beta-primeveroside (6-O-beta-d-xylopyranosyl-beta-d-glucopyranoside) at the beta-glycosidic bond of primeverose to aglycone, and releases aromatic alcoholic volatiles of aglycones. PD only accepts primeverose as the glycone substrate, but broadly accepts various aglycones, including 2-phenylethanol, benzyl alcohol, linalool, and geraniol. We determined the crystal structure of PD complexes using highly specific disaccharide amidine inhibitors, N-beta-primeverosylamidines, and revealed the architecture of the active site responsible for substrate specificity. We identified three subsites in the active site: subsite -2 specific for 6-O-beta-d-xylopyranosyl, subsite -1 well conserved among beta-glucosidases and specific for beta-d-glucopyranosyl, and wide subsite +1 for hydrophobic aglycone. Glu-470, Ser-473, and Gln-477 act as the specific hydrogen bond donors for 6-O-beta-d-xylopyranosyl in subsite -2. On the other hand, subsite +1 was a large hydrophobic cavity that accommodates various aromatic aglycones. Compared with aglycone-specific beta-glucosidases of the glycoside hydrolase family 1, PD lacks the Trp crucial for aglycone recognition, and the resultant large cavity accepts aglycone and 6-O-beta-d-xylopyranosyl together. PD recognizes the beta-primeverosides in subsites -1 and -2 by hydrogen bonds, whereas the large subsite +1 loosely accommodates various aglycones. The glycone-specific activity of PD for broad aglycone substrates results in selective and multiple release of temporally stored alcoholic volatile aglycones of beta-primeveroside.

Crystal structures of beta-primeverosidase in complex with disaccharide amidine inhibitors.,Saino H, Shimizu T, Hiratake J, Nakatsu T, Kato H, Sakata K, Mizutani M J Biol Chem. 2014 Jun 13;289(24):16826-34. doi: 10.1074/jbc.M114.553271. Epub, 2014 Apr 21. PMID:24753293^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.