Crystal structure of the pyridoxal-5'-phosphate dependent cystathionine beta-lyase from Escherichia coli at 1.83 angstrom
Crystal structure of the pyridoxal-5'-phosphate dependent cystathionine beta-lyase from Escherichia coli at 1.83 angstrom
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DOI：
10.1006/jmbi.1996.0508
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发表时间：
1996-09-20
影响因子：
5.6
通讯作者：
Messerschmidt, A
中科院分区：
文献类型：
--
作者：
Clausen, T;Huber, R;Messerschmidt, A
胱硫醚β-裂解酶（CBL）是PLP依赖性酶的γ-家族的成员，其裂解多种底物的C β-S键。对E.大肠杆菌的问题已经通过使用MIR相结合密度修正得到解决。使用同步辐射衍射数据，在1.83埃分辨率下，结构已被细化到15.2%的R因子。晶胞的不对称单元（空间群C222（1））包含两个2重对称相关的单体。通过晶体学和非晶体学对称性，得到了具有222对称性的同四聚体。CBL的每个单体可以用三个空间和功能不同的结构域来描述。N-末端结构域（残基1至60）由三个α-螺旋和一个β-链组成。它有助于四聚体的形成，并且是相邻亚基的活性位点的一部分。第二个结构域（残基61至256）含有PLP，并具有以七链β折叠作为中心部分的α/β结构。剩余的C末端结构域（残基257至395）通过长α螺旋连接到PLP结合结构域，由包装在反平行四链β折叠的溶剂可及侧的四个螺旋组成。C-末端和PLP-结合结构域的折叠以及活性位点的位置与氨基转移酶相似。活性位点中的大多数残基在转硫途径的酶中是高度保守的。此外，CBL与malY基因产物同源，表明PLP依赖性酶的α和γ家族之间的进化关系。β，β，β-三氟丙氨酸失活的CBL的结构已在2.3埃分辨率下细化至16.2%的R因子。这表明PLP结合残基Lys 210介导C（a）alpha和S（g）amma之间的质子转移。(C)1996年学术出版社
Cystathionine beta-lyase (CBL) is a member of the gamma-family of PLP-dependent enzymes, that cleaves C beta-S bonds of a broad variety of substrates. The crystal structure of CBL from E. coli has been solved using MIR phases in combination with density modification. The structure has been refined to an R-factor of 15.2% at 1.83 Angstrom resolution using synchroton radiation diffraction data. The asymmetric unit of the crystal cell (space group C222(1)) contains two monomers related by 2-fold symmetry. A homotetramer with 222 symmetry is built up by crystallographic and non-crystallographic symmetry. Each monomer of CBL can be described in terms of three spatially and functionally different domains. The N-terminal domain (residues 1 to 60) consists of three alpha-helices and one beta-strand. It contributes to tetramer formation and is part of the active site of the adjacent subunit. The second domain (residues 61 to 256) harbors PLP and has an alpha/beta-structure with a seven-stranded beta-sheet as the central part. The remaining C-terminal domain (residues 257 to 395), connected by a long alpha-helix to the PLP-binding domain, consists of four helices packed on the solvent-accessible side of an antiparallel four-stranded beta-sheet. The fold of the C-terminal and the PLP-binding domain and the location of the active site are similar to aminotransferases. Most of the residues in the active site are strongly conserved among the enzymes of the transsulfuration pathway. Additionally, CBL is homologous to the malY gene product indicating an evolutionary relationship between alpha and gamma-family of PLP-dependent enzymes. The structure of the beta,beta,beta-trifluoroalanine inactivated CBL has been refined at 2.3 Angstrom resolution to an R-factor of 16.2%. It suggests that Lys210, the PLP-binding residue, mediates the proton transfer between C(a)lpha and S(g)amma. (C) 1996 Academic Press Limited