The structure of a binary complex between a mammalian mevalonate kinase and ATP - Insights into the reaction mechanism and human inherited disease
The structure of a binary complex between a mammalian mevalonate kinase and ATP - Insights into the reaction mechanism and human inherited disease
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DOI：
10.1074/jbc.m200912200
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发表时间：
2002-05-17
影响因子：
4.8
通讯作者：
Kim, JJP
中科院分区：
文献类型：
--
作者：
Fu, ZJ;Wang, M;Kim, JJP
甲羟戊酸激酶催化甲羟戊酸的ATP依赖性磷酸化形成甲羟戊酸5-磷酸，甲羟戊酸5-磷酸是类异戊二烯和甾醇途径中的关键中间体。甲羟戊酸激酶活性缺乏与甲羟戊酸尿症和高免疫球蛋白血症D/周期性发热综合征（HIDS）有关。在2.4埃分辨率下测定了大鼠甲羟戊酸激酶与MgATP复合物的晶体结构。这种二聚体蛋白的每个单体由两个结构域组成，其活性位点位于结构域界面。与酶结合的ATP采用反构象，与詹氏甲烷球菌高丝氨酸激酶报道的syn构象相反。Mg 2+离子与ATP的β-和γ-磷酸以及Glu（193）和Ser（146）的侧链配位。Asp（204）与Lys（13）形成盐桥，进而与γ-磷酸相互作用。甲羟戊酸的模型可以放置在ATP的γ-磷酰基附近;因此，C5羟基位于距离Asp（204），Lys（13）和ATP的γ-磷酰基4埃的范围内。残基的这种排列强烈表明：1）Asp（204）从甲羟戊酸的C5羟基提取质子; 2）五配位的γ-磷酰基可以被Mg 2+、Lys（13）和Glu（193）稳定; 3）Lys（13）可能影响底物的C5羟基的pK（α）。V377 I和I268 T是HIDS患者中最常见的突变。瓦尔（377）位于距离活性位点超过18埃的位置，用Ile保守取代不可能产生无活性或不稳定的蛋白质。Ile-268位于二聚体界面，其Thr取代可能破坏二聚体形成。
Mevalonate kinase catalyzes the ATP-dependent phosphorylation of mevalonic acid to form mevalonate 5-phosphate, a key intermediate in the pathways of isoprenoids and sterols. Deficiency in mevalonate kinase activity has been linked to mevalonic aciduria and hyperimmunoglobulinemia D/periodic fever syndrome (HIDS). The crystal structure of rat mevalonate kinase in complex with MgATP has been determined at 2.4-Angstrom resolution. Each monomer of this dimeric protein is composed of two domains with its active site located at the domain interface. The enzyme-bound ATP adopts an anti conformation, in contrast to the syn conformation reported for Methanococcus jannaschii homoserine kinase. The Mg2+ ion is coordinated to both beta- and gamma-phosphates of ATP and side chains of Glu(193) and Ser(146). Asp(204) is making a salt bridge with Lys(13) which in turn interacts with the gamma-phosphate. A model of mevalonic acid can be placed near the gamma-phosphoryl group of ATP; thus, the C5 hydroxyl is located within 4 Angstrom from Asp(204), Lys(13), and the gamma-phosphoryl of ATP. This arrangement of residues strongly suggests: 1) Asp(204) abstracts the proton from C5 hydroxyl of mevalonate; 2) the penta-coordinated gamma-phosphoryl group may be stabilized by Mg2+, Lys(13), and Glu(193); and 3) Lys(13) is likely to influence the pK(a) of the C5 hydroxyl of the substrate. V377I and I268T are the most common mutations found in patients with HIDS. Val(377) is located over 18 Angstrom away from the active site and a conservative replacement with Ile is unlikely to yield an inactive or unstable protein. Ile-268 is located at the dimer interface, and its Thr substitution may disrupt dimer formation.