Crystal structure of butyrate kinase 2 from Thermotoga maritima, a member of the ASKHA superfamily of phosphotransferases.
Crystal structure of butyrate kinase 2 from Thermotoga maritima, a member of the ASKHA superfamily of phosphotransferases.
复制标题
来自海栖热袍菌（ASKHA 磷酸转移酶超家族成员）的丁酸激酶 2 的晶体结构。
DOI：
10.1128/jb.00906-08
复制
发表时间：
2009
影响因子：
3.2
通讯作者：
Hasson,MiriamS
中科院分区：
文献类型：
--
作者：
Diao,Jiasheng;Hasson,MiriamS
磷酰基的酶促转移是许多细胞过程控制的核心。磷酰基转移机制之一，乙酸激酶，是不完全理解。除了更好地理解乙酸激酶的机制外，丁酸激酶2（Buk 2）的结构知识将有助于解释活性位点结构，并提供底物特异性的结构基础信息。海栖热袍菌（Thermotoga maritima）的genebuk 2编码磷酸转移酶的ASKHA（acetate and sugar kinases/heat shock cognate/actin）超家族的成员。编码的蛋白Buk 2催化丁酸和异丁酸的磷酸化。测定了Buk 2与5′-三磷酸（β，γ-亚甲基）腺苷复合物的2.5-A β晶体结构。Buk 2像一个开壳的蛤蜊一样折叠，两个域中的每一个都代表两个壳中的一个。在N-和C-末端结构域之间的开放活性位点裂缝中，活性位点残基由两个组氨酸、两个组氨酸和一簇疏水残基组成。Buk 2的ATP结合区在C-末端结构域中由用于核苷酸结合的丰富甘氨酸组成，并且ATP结合基序与ASKHA超家族的其他成员相似。该酶以八聚体形式存在，其中分子间半胱氨酸之间形成四个二硫键。序列比对和结构叠加确定单体Buk 2结构的简单性，一个可能的底物结合位点，催化磷酰基转移的关键残基，以及Buk 2，乙酸和丙酸激酶之间的底物特异性差异。讨论了可能的酶作用机制。
The enzymatic transfer of phosphoryl groups is central to the control of many cellular processes. One of the phosphoryl transfer mechanisms, that of acetate kinase, is not completely understood. Besides better understanding of the mechanism of acetate kinase, knowledge of the structure of butyrate kinase 2 (Buk2) will aid in the interpretation of active-site structure and provide information on the structural basis of substrate specificity. The genebuk2fromThermotoga maritimaencodes a member of the ASKHA (acetate and sugar kinases/heat shock cognate/actin) superfamily of phosphotransferases. The encoded protein Buk2 catalyzes the phosphorylation of butyrate and isobutyrate. We have determined the 2.5-Å crystal structure of Buk2 complexed with (β,γ-methylene) adenosine 5′-triphosphate. Buk2 folds like an open-shelled clam, with each of the two domains representing one of the two shells. In the open active-site cleft between the N- and C-terminal domains, the active-site residues consist of two histidines, two arginines, and a cluster of hydrophobic residues. The ATP binding region of Buk2 in the C-terminal domain consists of abundant glycines for nucleotide binding, and the ATP binding motif is similar to those of other members of the ASKHA superfamily. The enzyme exists as an octamer, in which four disulfide bonds form between intermolecular cysteines. Sequence alignment and structure superposition identify the simplicity of the monomeric Buk2 structure, a probable substrate binding site, the key residues in catalyzing phosphoryl transfer, and the substrate specificity differences among Buk2, acetate, and propionate kinases. The possible enzyme mechanisms are discussed.