Disruption of the coenzyme binding site and dimer interface revealed in the crystal structure of mitochondrial aldehyde dehydrogenase "Asian" variant
Disruption of the coenzyme binding site and dimer interface revealed in the crystal structure of mitochondrial aldehyde dehydrogenase "Asian" variant
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DOI：
10.1074/jbc.m502345200
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发表时间：
2005-08-26
影响因子：
4.8
通讯作者：
Hurley, TD
中科院分区：
文献类型：
--
作者：
Larson, HN;Weiner, H;Hurley, TD
线粒体醛脱氢酶 (ALDH2) 是氧化乙醇衍生的乙醛的主要酶。大约 40% 的东亚人口中发现了一种几乎无活性的酶 ALDH2*2。该酶变体由位于寡聚结构域内的残基 487 处的谷氨酸替换为赖氨酸来定义。 ALDH2*2 的辅酶 NAD(+) Km 增加，k(cat) 减少，导致体内活性低。在这里，我们报道了 ALDH2*2 的 2.1 埃晶体结构。该结构显示位于二聚体界面处的大无序区域，其中包括大部分辅酶结合裂口和形成活性位点基础的残基环。由于这些结构变化，变体酶表现出其催化结构域和辅酶结合结构域相对于寡聚化结构域的刚体旋转。这些结构扰动是赖氨酸 487 无法与精氨酸 264 和 475 形成重要的稳定氢键的直接结果。因此，该变体表现出的辅酶 K-m 升高可能反映了重建该位点以进行生产性辅酶结合的能量损失，而活性位点附近的结构变化与降低的 V-max 一致。
Mitochondrial aldehyde dehydrogenase ( ALDH2) is the major enzyme that oxidizes ethanol-derived acetaldehyde. A nearly inactive form of the enzyme, ALDH2*2, is found in about 40% of the East Asian population. This variant enzyme is defined by a glutamate to lysine substitution at residue 487 located within the oligomerization domain. ALDH2*2 has an increased Km for its coenzyme, NAD(+), and a decreased k(cat), which lead to low activity in vivo. Here we report the 2.1 angstrom crystal structure of ALDH2*2. The structure shows a large disordered region located at the dimer interface that includes much of the coenzyme binding cleft and a loop of residues that form the base of the active site. As a consequence of these structural changes, the variant enzyme exhibits rigid body rotations of its catalytic and coenzyme-binding domains relative to the oligomerization domain. These structural perturbations are the direct result of the inability of lysine 487 to form important stabilizing hydrogen bonds with arginines 264 and 475. Thus, the elevated K-m for coenzyme exhibited by this variant probably reflects the energetic penalty for reestablishing this site for productive coenzyme binding, whereas the structural alterations near the active site are consistent with the lowered V-max.