钩端螺旋体Homoserine O-acetyltransferase结构解析与催化机理研究，人的Coactosin-l
发布时间：2018-09-14 17:51
【摘要】：LiHTA—高丝氨酸氧乙酰转移酶(Homoserinc O-acetyltransferase，HTA，EC2．3．1．31)是在微生物和植物体内甲硫氨酸的生物合成途径中的第一个酶。它催化乙酰辅酶A的乙酰基转移到高丝氨酸上，这是一个两步的乒乓反应机制。我们用硒的单波长反常衍射的方法解析了来源于Leptospira interrogans——一种强致病性的钩端螺旋体——的HTA的分辨率为2.2(?)的晶体结构。HTA结构是由两个独立的结构域组成，一个核心的a／β结构域，包含有催化位点，另一个是由a螺旋束构成的Lid结构域。整体上来说，这种折叠方式属于a／β水解酶超家族，特征是该家族的活性位点的催化三联体位于结构的特定loop上。我们的精细结构发现催化三联体的组氨酸和丝氨酸都是处于两种构象，并且与催化相关的残基的构象很多具有较大的柔性。根据我们的结果我们给出了一个更为精细的推测的反应机理，其中组氨酸双构象起到了决定性的作用。 hCLP—人的肌动蛋白辅助蛋白类似蛋白(Human coactosin-like protein，，hCLP)是一种肌动蛋白丝的结合蛋白，它与肌动蛋白单体没有结合作用。它与5—磷脂酶无论在体外还是体内都有结合作用，在调节肌动蛋白和5—磷脂酶的活性方面起到了重要的作用。帽子蛋白阻碍肌动蛋白的多聚，而肌动蛋白辅助蛋白可以阻碍帽子蛋白的活性，但是肌动蛋白辅助蛋白本身对肌动蛋白的聚合或者解聚都没有任何影响。我们用硒的多波长反常衍射的方法解析了hCLP的晶体结构。该结构表明它与ADF—H结构域有着高度的结构相似性，尽管一级序列同源性非常低。我们发现一些保守的疏水残基很可能对这种折叠同源性有重要贡献。该结构表明CLP以一种非常不同于ADF／Cofilin家族的方式与肌动蛋白丝结合。结合之前的突变研究，我们分别分析了CLP与肌动蛋白丝和5—磷脂酶的结合位点。这两个结合位点在空间上非常的接近，很可能就此排除了肌动蛋白丝和5—磷脂酶同时结合到CLP上的可能性。
[Abstract]:LiHTA-homoserinc O-acetyltransferase (HTA, EC2.3.1.31) is the first enzyme in the biosynthetic pathway of methionine in microorganisms and plants. It catalyzes the acetyltransference of acetyl coenzyme A to homoserine, a two-step ping-pong reaction mechanism. We used a single wavelength trans of selenium. The crystal structure of HTA derived from Leptospira interrogans, a highly pathogenic leptospira, has a resolution of 2.2 (?). The HTA structure consists of two independent domains, one core a/beta domain containing catalytic sites and the other a helix beam composed of a Lid domain. In general, this folding pattern belongs to the a/beta hydrolase superfamily and is characterized by the fact that the catalytic triplets of the active sites of the family are located on specific loops of the structure. Based on our results, we present a more delicate speculative reaction mechanism in which the histidine diconformation plays a decisive role.
HCLP-human actin-like protein (hCLP) is a binding protein of actin filament, which does not bind to actin monomer. It binds to 5-phospholipase both in vitro and in vivo and plays an important role in regulating the activity of actin and 5-phospholipase. Cap proteins inhibit the aggregation of actin, and actin-cofactor proteins inhibit the activity of cap proteins, but actin-cofactor proteins themselves have no effect on the aggregation or depolymerization of actin. We analyzed the crystal structure of hCLP by means of selenium multi-wavelength anomalous diffraction. We found that some conserved hydrophobic residues are likely to contribute significantly to this folding homology. This structure indicates that CLP binds to actin filaments in a very different way from the ADF/Cofilin family. We analyzed the binding sites of CLP with actin filament and 5-phospholipase respectively. These two binding sites are very close in space, which may exclude the possibility of actin filament and 5-phospholipase binding to CLP simultaneously.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2006
【分类号】：R377.5
本文编号：2243437
[Abstract]:LiHTA-homoserinc O-acetyltransferase (HTA, EC2.3.1.31) is the first enzyme in the biosynthetic pathway of methionine in microorganisms and plants. It catalyzes the acetyltransference of acetyl coenzyme A to homoserine, a two-step ping-pong reaction mechanism. We used a single wavelength trans of selenium. The crystal structure of HTA derived from Leptospira interrogans, a highly pathogenic leptospira, has a resolution of 2.2 (?). The HTA structure consists of two independent domains, one core a/beta domain containing catalytic sites and the other a helix beam composed of a Lid domain. In general, this folding pattern belongs to the a/beta hydrolase superfamily and is characterized by the fact that the catalytic triplets of the active sites of the family are located on specific loops of the structure. Based on our results, we present a more delicate speculative reaction mechanism in which the histidine diconformation plays a decisive role.
HCLP-human actin-like protein (hCLP) is a binding protein of actin filament, which does not bind to actin monomer. It binds to 5-phospholipase both in vitro and in vivo and plays an important role in regulating the activity of actin and 5-phospholipase. Cap proteins inhibit the aggregation of actin, and actin-cofactor proteins inhibit the activity of cap proteins, but actin-cofactor proteins themselves have no effect on the aggregation or depolymerization of actin. We analyzed the crystal structure of hCLP by means of selenium multi-wavelength anomalous diffraction. We found that some conserved hydrophobic residues are likely to contribute significantly to this folding homology. This structure indicates that CLP binds to actin filaments in a very different way from the ADF/Cofilin family. We analyzed the binding sites of CLP with actin filament and 5-phospholipase respectively. These two binding sites are very close in space, which may exclude the possibility of actin filament and 5-phospholipase binding to CLP simultaneously.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2006
【分类号】：R377.5
【共引文献】
相关博士学位论文 前2条
1 戴海明;人Coactosin Like Protein及MICAL_1 Calponin Homolgy结构域的结构与功能研究[D];中国科学技术大学;2006年
2 李泉;蛋白质局部结构—局部序列统计势的构建以及RNA结合位点的预测[D];中国科学技术大学;2008年
相关硕士学位论文 前3条
1 贾佳;环氧化物水解酶序列识别和分类模型的构建[D];浙江大学;2006年
2 单萍;CLP基因的克隆、表达及生化特性的研究[D];东北师范大学;2009年
3 吴进珍;并行蚁群优化在蛋白质结构预测中的应用研究[D];苏州大学;2010年
本文编号：2243437
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