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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >Three-dimensional structure of the Gly121Tyr dimeric form of ornithine decarboxylase from Lactobacillus 30a.
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Three-dimensional structure of the Gly121Tyr dimeric form of ornithine decarboxylase from Lactobacillus 30a.

机译：Gly121Tyr的三维结构二聚的形式的鸟氨酸脱羧酶乳酸菌30 a。

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摘要

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 P3(2)21, with unit-cell parameters a = 111.8, c = 135.9 A 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 A 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.
机译：鸟氨酸脱羧酶催化转化鸟氨酸初腐胺聚胺通路。30 (ODC)乳酸菌是990612哒六为dodecamer组成的。点突变(Gly121Tyr),以防止被发现协会dodecamers二聚体。二聚的蛋白质结晶在pH值7.0在鸟嘌呤核苷三磷酸(三磷酸鸟苷)。水晶属于空间群P3(2) 21日晶胞参数= 111.8,和135.9 c =不对称单元单体。是由分子置换和精制使用模拟退火R = 0.2112. 详细分析了。绑定模式不同于三磷酸鸟苷在大多数g或gtpase。这个绑定方案似乎是三个赖氨酸,Lys190 Lys374 Lys382,形成盐桥梁的三磷酸盐,Thr191氢键的鸟嘌呤碱。此外,结构表明,翼域中的一些灵活性,可以其蛋白质的定位适应变化它的环境。本机的酶,与一致观察酶活性不取决于其dodecameric状态。

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