From structure to function:: YrbI from Haemophilus influenzae (HI1679) is a phosphatase
From structure to function:: YrbI from Haemophilus influenzae (HI1679) is a phosphatase
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DOI：
10.1002/prot.10057
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发表时间：
2002-03-01
影响因子：
2.9
通讯作者：
Herzberg, O
中科院分区：
文献类型：
--
作者：
Parsons, JF;Lim, K;Herzberg, O
用1.67埃分辨率测定了流感嗜血杆菌YrbI蛋白(HI1679)的晶体结构。该蛋白质的功能以前没有被指定，它在序列数据库中被注释为假设的。该蛋白显示出α/β-水解酶折叠(也称为罗斯曼折叠)，与L-2-卤酸脱卤酶(HAD)超家族的折叠最为相似。在这一观察之后，详细的序列分析揭示了与HAD超家族的两个成员，钙离子ATPase和磷酸丝氨酸磷酸酶的β结构域的远程同源性。HI1679的19 kDa链在溶液中和晶体中都形成了四聚体。这四个单体排列成环，使得四个β-发夹环，每个插入在核心α/β折叠的第一个β链之后，在组件的中心形成一个八链桶。亚基界面上有四个活性中心。每个活性中心都被钴离子占据，钴离子是一种用于结晶的金属。钴与两个天冬氨酸侧链、一个主链氧和三个溶剂分子八面体配位，表明生理金属可能是镁。HI1679能降解多种磷酸盐，包括6-磷酸葡萄糖酸和磷酸酪氨酸，这表明它在体内具有磷酸酶的功能。生理底物尚未确定，但该基因在yrb操纵子上的位置表明参与了糖的代谢。(C)2002年Wiley-Liss，Inc.
The crystal structure of the YrbI protein from Haemophilus influenzae (HI1679) was determined at a 1.67-Angstrom resolution. The function of the protein had not been assigned previously, and it is annotated as hypothetical in sequence databases. The protein exhibits the alpha/beta-hydrolase fold (also termed the Rossmann fold) and resembles most closely the fold of the L-2-haloacid dehalogenase (HAD) superfamily. Following this observation, a detailed sequence analysis revealed remote homology to two members of the HAD superfamily, the beta-domain of Ca2+ ATPase and phosphoserine phosphatase. The 19-kDa chains of HI1679 form a tetramer both in solution and in the crystalline form. The four monomers are arranged in a ring such that four beta-hairpin loops, each inserted after the first beta-strand of the core alpha/beta-fold, form an eight-stranded barrel at the center of the assembly. Four active sites are located at the subunit interfaces. Each active site is occupied by a cobalt ion, a metal used for crystallization. The cobalt is octahedrally coordinated to two aspartate side-chains, a backbone oxygen, and three solvent molecules, indicating that the physiological metal may be magnesium. HI1679 hydrolyzes a number of phosphates, including 6-phosphogluconate and phosphotyrosine, suggesting that it functions as a phosphatase in vivo. The physiological substrate is yet to be identified; however the location of the gene on the yrb operon suggests involvement in sugar metabolism. (C) 2002 Wiley-Liss, Inc.