The 1.8 A crystal structure of catechol 1,2-dioxygenase reveals a novel hydrophobic helical zipper as a subunit linker.
The 1.8 A crystal structure of catechol 1,2-dioxygenase reveals a novel hydrophobic helical zipper as a subunit linker.
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DOI：
10.1016/s0969-2126(00)00122-2
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发表时间：
2000-04
期刊：
影响因子：
5.7
通讯作者：
M. Vetting;D. Ohlendorf
中科院分区：
文献类型：
--
作者：
M. Vetting;D. Ohlendorf
背景：内二醇双加氧酶催化儿茶酚衍生物转化为柠檬酸循环中间体的关键环裂解步骤。邻苯二酚1，2-双加氧酶（1，2-CTD）具有基本的设计结构-每个单体具有一个催化非血红素铁离子（α Fe 3+）2的同二聚体。这与典型的二醇内双加氧酶原儿茶酸酯3，4-双加氧酶（3，4-PCD）形成更多样的寡聚体（如（αβ Fe 3+）2- 1,2）不同。ADP 1（Ac 1，2-CTD）通过单次同晶置换解析并精确到2.0 μ m分辨率。与邻苯二酚和4-甲基邻苯二酚复合的酶的结构也分别在1.9 μ m和1.8 μ m的分辨率下确定。虽然铁配体的特征是相似的，但Ac 1，2-CTD与3，4-PCD的不同之处在于，只有一个亚基用于形成每个活性位点空腔。此外，一种新的“螺旋拉链”，由每个亚基的五个N-末端螺旋组成，形成分子二聚体轴。两个磷脂被意外地发现结合在一个8 × 35 μ m的疏水隧道内，沿着这个轴沿着.结论：Ac 1，2-CTD的螺旋拉链结构域在其他已知结构的蛋白质中没有等价物。序列分析表明，该结构域是1，2-CTD家族所有成员的共同基序。儿茶酚和4-甲基儿茶酚的复合物是迄今为止二醇内双加氧酶的最高分辨率的复合物结构。此外，他们证实了在3，4-PCD中观察到的几个观察结果，包括结合外源配体后的配体置换。这里提出的结构是一个新的二醇内双加氧酶家族的第一个。
Background:Intradiol dioxygenases catalyze the critical ring-cleavage step in the conversion of catecholate derivatives to citric acid cycle intermediates. Catechol 1,2-dioxygenases (1,2-CTDs) have a rudimentary design structure — a homodimer with one catalytic non-heme ferric ion per monomer, that is (αFe3+)2. This is in contrast to the archetypical intradiol dioxygenase protocatechuate 3,4-dioxygenase (3,4-PCD), which forms more diverse oligomers, such as (αβFe3+)2–12.Results: The crystal structure of 1,2-CTD fromAcinetobactersp. ADP1 (Ac 1,2-CTD) was solved by single isomorphous replacement and refined to 2.0 Å resolution. The structures of the enzyme complexed with catechol and 4-methylcatechol were also determined at resolutions of 1.9 Å and 1.8 Å, respectively. While the characteristics of the iron ligands are similar, Ac 1,2-CTD differs from 3,4-PCDs in that only one subunit is used to fashion each active-site cavity. In addition, a novel ‘helical zipper', consisting of five N-terminal helices from each subunit, forms the molecular dimer axis. Two phospholipids were unexpectedly found to bind within an 8 × 35 Å hydrophobic tunnel along this axis.Conclusions:The helical zipper domain of Ac 1,2-CTD has no equivalent in other proteins of known structure. Sequence analysis suggests the domain is a common motif in all members of the 1,2-CTD family. Complexes with catechol and 4-methylcatechol are the highest resolution complex structures to date of an intradiol dioxygenase. Furthermore, they confirm several observations seen in 3,4-PCDs, including ligand displacement upon binding exogenous ligands. The structures presented here are the first of a new family of intradiol dioxygenases.