Kristensen Ole, Ross Birthe, Gajhede Michael
Biostructural Research, Department of Medicinal Chemistry, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
J Mol Biol. 2008 Feb 1;375(5):1469-76. doi: 10.1016/j.jmb.2007.11.073. Epub 2007 Dec 4.
The crystal structure of the prototype exopolyphosphatase/guanosine pentaphosphate phosphohydrolase protein family member from Aquifex aeolicus in complex with the intracellular second messenger guanosine tetraphosphate was determined at 2.7-A resolution. The hydrolytic base is identified as E119. The dual specificity established for the Escherichia coli homolog is shown to be compatible with a common active site for guanosine pentaphosphate and polyphosphate hydrolysis. Distinct and different degrees of closure between the two domains of the enzyme are associated with substrate binding. The arginines R22 and R267, residing in different domains, are crucial for guanosine pentaphosphate specificity as they interact with the unique 3'-ribose phosphorylation.
嗜热栖热菌中首个胞外多聚磷酸酶/鸟苷五磷酸磷酸水解酶蛋白家族成员与细胞内第二信使鸟苷四磷酸复合物的晶体结构在2.7埃分辨率下得以确定。水解碱基被鉴定为E119。已证明大肠杆菌同系物所具有的双重特异性与鸟苷五磷酸和多聚磷酸水解的共同活性位点相兼容。酶的两个结构域之间不同程度的闭合与底物结合相关。位于不同结构域的精氨酸R22和R267对鸟苷五磷酸特异性至关重要，因为它们与独特的3'-核糖磷酸化相互作用。
