Structure of the Streptococcus agalactiae family II inorganic pyrophosphatase at 2.80 A resolution.
Structure of the Streptococcus agalactiae family II inorganic pyrophosphatase at 2.80 A resolution.
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无乳链球菌 II 族无机焦磷酸酶的结构，分辨率为 2.80 A。
DOI：
10.1107/s0907444907019695
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Goldman,Adrian
中科院分区：
文献类型：
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作者：
Rantanen,MikaK;Lehtiö,Lari;Rajagopal,Lakshmi;Rubens,CraigE;Goldman,Adrian
无乳链球菌是一种引起新生儿和免疫功能低下成人感染的原核生物，具有丝氨酸/苏氨酸蛋白激酶（STK）信号级联。其中一个靶标是II族无机焦磷酸酶，它的结构通过分子替换得到了解，并在2.80 Å分辨率下得到了细化，R因子为19.2% （Rfree = 26.7%）。不对称单元中的两个单体由非结晶双轴连接，而生物二聚体由结晶双轴连接。每个单体含有焦磷酸盐类似物亚胺二磷酸（PNP）和每个活性位点三个金属离子：两个Mn2+离子在M1和M2位点，一个Mg2+离子在M3位点。酶是封闭构象。与其他II族酶一样，该结构由两个结构域（残基1-191和198-311）组成，活性位点位于它们之间。Lys298在活性位点的构象与先前观察到的构象不同，它以独特的方式与保守的DHH基序协调。该结构表明，Ser150, Ser194， Ser195和Ser296是丝氨酸/苏氨酸激酶和磷酸酶最有可能的靶点，因为它们是表面可接近的，要么在活性位点，要么在两个结构域之间的铰链区域。
Streptococcus agalactiae, a prokaryote that causes infections in neonates and immunocompromised adults, has a serine/threonine protein kinase (STK) signalling cascade. The structure of one of the targets, a family II inorganic pyrophosphatase, has been solved by molecular replacement and refined at 2.80 Å resolution to an R factor of 19.2% (Rfree = 26.7%). The two monomers in the asymmetric unit are related by a noncrystallographic twofold axis, but the biological dimer is formed by a crystallographic twofold. Each monomer contains the pyrophosphate analogue imidodiphosphate (PNP) and three metal ions per active site: two Mn2+ ions in sites M1 and M2 and an Mg2+ ion in site M3. The enzyme is in the closed conformation. Like other family II enzymes, the structure consists of two domains (residues 1–191 and 198–311), with the active site located between them. The conformation of Lys298 in the active site is different from those observed previously and it coordinates to the conserved DHH motif in a unique way. The structure suggests that Ser150, Ser194, Ser195 and Ser296 are the most likely targets for the Ser/Thr kinase and phosphatase because they are surface-accessible and either in the active site or in the hinge region between the two domains.