Monomeric sarcosine oxidase: structure of a covalently flavinylated amine oxidizing enzyme.
Monomeric sarcosine oxidase: structure of a covalently flavinylated amine oxidizing enzyme.
复制标题
DOI：
10.1016/s0969-2126(99)80043-4
复制
发表时间：
1999-03
期刊：
影响因子：
5.7
通讯作者：
P. Trickey;M. Wagner;M. Jorns;F. Mathews
中科院分区：
文献类型：
--
作者：
P. Trickey;M. Wagner;M. Jorns;F. Mathews
背景：单体肌氨酸氧化酶（MSOXs）是最近发现的真核和原核酶家族中最简单的成员之一，它们与各种二级或叔胺基酸催化类似的氧化反应，并含有共价结合的黄素。该家族的其他成员包括异四聚体肌氨酸氧化酶，n -甲基色氨酸氧化酶和胡椒酸氧化酶。哺乳动物肌氨酸脱氢酶和二甲基甘氨酸脱氢酶可能是近亲。结果：芽孢杆菌MSOX的x射线晶体结构。在大肠杆菌中表达的B-0618已通过硒代蛋氨酸取代酶晶体的多波长异常色散（MAD）在2.0 Å分辨率下进行了解析。在不对称单元中，属于两个MSOX分子的14个硒位点被用于MAD相位，并定义了用于电子密度平均的局部双重对称轴。测定了天然酶和两种酶抑制剂复合物的结构。结论：MSOX是一种双结构域蛋白，其整体拓扑结构与d -氨基酸氧化酶最为相似，具有14%的序列同源性。黄素环位于一个非常基本的环境中，与精氨酸、赖氨酸、组氨酸的侧链和螺旋偶极子的n端接触。黄素通过8α - s -半胱氨酸键共价连接到催化结构域的Cys315上。共价连接可能是通过与正侧链和螺旋偶极子的相互作用而自催化的。底物羧酸盐与黄素环表面上方的两个基本侧链Arg52和Lys348之间的氢键可能稳定了底物与黄素环的结合。
Background:Monomeric sarcosine oxidases (MSOXs) are among the simplest members of a recently recognized family of eukaryotic and prokaryotic enzymes that catalyze similar oxidative reactions with various secondary or tertiary amino acids and contain covalently bound flavins. Other members of this family include heterotetrameric sarcosine oxidase,N-methyltryptophan oxidase and pipecolate oxidase. Mammalian sarcosine dehydrogenase and dimethylglycine dehydrogenase may be more distantly related family members.Results:The X-ray crystal structure of MSOX fromBacillussp.B-0618, expressed inEscherichia coli, has been solved at 2.0 Å resolution by multiwavelength anomalous dispersion (MAD) from crystals of the selenomethionine-substituted enzyme. Fourteen selenium sites, belonging to two MSOX molecules in the asymmetric unit, were used for MAD phasing and to define the local twofold symmetry axis for electron-density averaging. The structures of the native enzyme and of two enzyme–inhibitor complexes were also determined.Conclusions:MSOX is a two-domain protein with an overall topology most similar to that of D-amino acid oxidase, with which it shares 14% sequence identity. The flavin ring is located in a very basic environment, making contact with sidechains of arginine, lysine, histidine and the N-terminal end of a helix dipole. The flavin is covalently attached through an 8α–S-cysteinyl linkage to Cys315 of the catalytic domain. Covalent attachment is probably self-catalyzed through interactions with the positive sidechains and the helix dipole. Substrate binding is probably stabilized by hydrogen bonds between the substrate carboxylate and two basic sidechains, Arg52 and Lys348, located above thereface of the flavin ring.