Three-dimensional structure of the Gly121Tyr dimeric form of ornithine decarboxylase from Lactobacillus 30a.
Three-dimensional structure of the Gly121Tyr dimeric form of ornithine decarboxylase from Lactobacillus 30a.
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来自乳杆菌 30a 的鸟氨酸脱羧酶的 Gly121Tyr 二聚体形式的三维结构。
DOI：
10.1107/s0907444999010756
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Hackert,ML
中科院分区：
文献类型：
--
作者：
Vitali,J;Carroll,D;Chaudhry,RG;Hackert,ML
鸟氨酸脱羧酶在多胺途径的起始处催化鸟氨酸转化为腐胺。来自乳杆菌 30a 的鸟氨酸脱羧酶 (ODC) 是由六个同二聚体组成的 990612 Da 十二聚体。发现单点突变 (Gly121Tyr) 可以阻止二聚体结合成十二聚体。在三磷酸鸟苷 (GTP) 存在下，二聚体蛋白在 pH 7.0 下结晶。晶体属于 P3221 空间群，晶胞参数 a = 111.8，c = 135.9 Å，不对称单元中有一个单体。该结构通过分子置换确定，并使用模拟退火精炼至 R = 0.211（分辨率为 2.7 Å）。详细分析了 GTP 结合位点。该蛋白表现出一种新颖的 GTP 结合模式，与大多数 G 蛋白或 GTP 酶中所见的结合模式不同。该结合方案的核心似乎是三个赖氨酸：Lys190、Lys374 和 Lys382（它们与三种磷酸盐形成盐桥）以及 Thr191（与鸟嘌呤碱基形成氢键）。此外，该结构表明翼结构域存在一定的灵活性，当蛋白质适应其环境时，它可以改变其方向。活性位点与天然酶的活性位点相似，这与酶活性不依赖于其十二聚体状态的观察结果一致。
Ornithine decarboxylases catalyze the conversion of ornithine to putrescine at the beginning of the polyamine pathway. Ornithine decarboxylase (ODC) from Lactobacillus 30a is a 990612 Da dodecamer composed of six homodimers. A single point mutation (Gly121Tyr) was found to prevent association of dimers into dodecamers. The dimeric protein has been crystallized at pH 7.0 in the presence of guanosine triphosphate (GTP). Crystals belong to space group P3221, with unit-cell parameters a = 111.8, c = 135.9 Å and one monomer in the asymmetric unit. The structure was determined by molecular replacement and refined using simulated annealing to R = 0.211 at 2.7 Å resolution. The GTP-binding site was analyzed in detail. The protein exhibits a novel binding mode for GTP which is different from that seen in most G-proteins or GTPases. Central to this binding scheme appear to be three lysines, Lys190, Lys374 and Lys382, which form salt bridges with the three phosphates, and Thr191, which hydrogen bonds with the guanine base. Furthermore, the structure suggests that there is some flexibility in the wing domain, which can change its orientation as the protein adapts to its environment. The active site is similar to that of the native enzyme, consistent with the observation that the enzyme activity does not depend on its dodecameric state.