The refined crystal structure of Drosophila lebanonensis alcohol dehydrogenase at 1.9 Å resolution
The refined crystal structure of Drosophila lebanonensis alcohol dehydrogenase at 1.9 Å resolution
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DOI：
10.1006/jmbi.1998.2015
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发表时间：
1998-09-18
影响因子：
5.6
通讯作者：
Ladenstein, R
中科院分区：
文献类型：
--
作者：
Benach, J;Atrian, S;Ladenstein, R
果蝇醇脱氢酶（Drosophila alcohol dehydrogenase， DADH; EC 1.1.1.1）是一种依赖于NAD(H)的氧化还原酶，属于短链脱氢酶/还原酶（SDR）家族。这种同型二聚体酶在果蝇体内催化醇脱氢成酮或醛，以达到代谢同化和解毒的目的。在1.9埃的分辨率下，采用Patterson方法对具有生物化学特征的SDR家族成员之一DADH的载子形式的晶体结构进行了解析。通过晶体学细化和电子密度平均对初始模型进行改进，r因子= 20.5%,X-free = 23.8%。DADH亚基表现为α / β单域结构，具有典型的NAD(H)结合基序（Rossmann折叠）。一个亚基的肽链被折叠成一个中央的八链，每侧有三个α螺旋。二聚体具有局部2重对称性。二聚体结合由一个四螺旋基序和每个亚基的两个c端环主导，这在已知结构的SDR酶中是一个独特的结构特征。三种结构特征是活动站点架构的特征。(1)由邻近亚基的柔性环（33个残基）和c端尾部（11个残基）覆盖的深空腔。空腔的疏水表面可能增加这种酶对仲脂肪族醇的特异性。(2)已知催化三联体（Ser138, Tyrl51, Lys155）的残基在一线参与酶催化。Tyr151羟基与Lys155侧链形成离子键。初步的静电计算提供了证据，表明Tyrl51的活性形式是生理ph下的酪氨酸离子。(3)在催化三联体侧链的氢键距离上，三个有序的水分子可能对DADH催化中的质子释放步骤有重要意义。基于三元结构的序列比对与十个已知三维结构的SDR家族成员提出了一个由四组残基组成的模型，该模型将观察到的低程度序列同一性与非常相似的折叠模式和几乎相同的催化残基分布联系起来。(C) 1998学术出版社。
Drosophila alcohol dehydrogenase (DADH; EC 1.1.1.1) is a NAD(H)dependent oxidoreductase belonging to the short-chain dehydrogenases/ reductases (SDR) family. This homodimeric enzyme catalyzes the dehydrogenation of alcohols to their respective ketones or aldehydes in the fruit-fly Drosophila, both for metabolic assimilation and detoxification purposes. The crystal structure of the apo form of DADH, one of the first biochemically characterized member of the SDR family, was solved at 1.9 Angstrom resolution by Patterson methods. The initial model was improved by crystallographic refinement accompanied by electron density averaging, R-factor = 20.5%, X-free = 23.8%.DADH subunits show an alpha/beta single domain structure with a characteristic NAD(H) binding motif (Rossmann fold). The peptide chain of a subunit is folded into a central eight-stranded beta-sheet flanked on each side by three alpha-helices. The dimers have local 2-fold symmetry. Dimer association is dominated by a four-helix bundle motif as well as two C-terminal loops from each subunit, which represent a unique structural feature in SDR enzymes with known structure.Three structural features are characteristic for the active site architecture. (1) A deep cavity which is covered by a flexible loop (33 residues) and the C-terminal tail (11 residues) from the neighboring subunit. The hydrophobic surface of the cavity is likely to increase the specificity of this enzyme towards secondary aliphatic alcohols. (2) The residues of the catalytic triad (Ser138, Tyrl51, Lys155) are known to be involved in enzymatic catalysis in the first Line. The Tyr151 OH group is involved in an ionic bond with the Lys155 side-chain. Preliminary electrostatic calculations have provided evidence that the active form of Tyrl51 is a tyrosinate ion at physiological pH. (3) Three well-ordered water molecules in hydrogen bond distance to side-chains of the catalytic triad may be significant for the proton release steps in DADH catalysis.A ternary structure-based sequence alignment with ten members of the SDR family with known three-dimensional structure has suggested to define a model consisting of four groups of residues, which relates the observed low degree of sequence identity to quite similar folding patterns and nearly identical distributions of residues involved in catalysis. (C) 1998 Academic Press.