New Insights into the Mechanism of Nucleoside Hydrolases from the Crystal Structure of the Escherichia coli YbeK Protein Bound to the Reaction Product
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- 作者：Laura Muzzolini ; Wim Versé ; es ; Paola Tornaghi ; Els Van Holsbeke ; Jan Steyaert ; and Massimo Degano
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：January 24, 2006
- 年：2006
- 卷：45
- 期：3
- 页码：773 - 782
- 全文大小：532K
- 年卷期：v.45,no.3(January 24, 2006)
- ISSN：1520-4995
文摘
Nucleoside hydrolases (NHs) are enzymes that catalyze the excision of the N-glycosidic bondin nucleosides to allow recycling of the nitrogenous bases. The fine details of the catalytic mechanismand the structural features imposing the substrate specificity of the various members of the NH family arestill debated. Here we present the functional characterization of the Escherichia coli YbeK (RihA) proteinas a pyrimidine nucleoside-preferring NH and its first crystal structure to 1.8 Å resolution. The enzymeactive site is occupied by either the 
or 
anomer of ribose and provides the first structural descriptionof the binding of the NH reaction product. While the amino acid residues involved in ribosyl binding arestrictly conserved in pyrimidine-specific NHs, the residues involved in specific interactions with thenitrogenous bases differ considerably. Further comparison of the active site architecture of YbeK withthe related NHs establishes structural determinants involved in triggering the conformational transitionbetween the open and closed structures and suggests a mechanism for product release.
or anomer of ribose and provides the first structural descriptionof the binding of the NH reaction product. While the amino acid residues involved in ribosyl binding arestrictly conserved in pyrimidine-specific NHs, the residues involved in specific interactions with thenitrogenous bases differ considerably. Further comparison of the active site architecture of YbeK withthe related NHs establishes structural determinants involved in triggering the conformational transitionbetween the open and closed structures and suggests a mechanism for product release.