Insights into the catalytic mechanism of the Bcp family: Functional and structural analysis of Bcp1 from Sulfolobus solfataricus
Insights into the catalytic mechanism of the Bcp family: Functional and structural analysis of Bcp1 from Sulfolobus solfataricus
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DOI：
10.1002/prot.22408
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发表时间：
2009-09-01
影响因子：
2.9
通讯作者：
De Simone, Giuseppina
中科院分区：
文献类型：
--
作者：
D'Ambrosio, Katia;Limauro, Danila;De Simone, Giuseppina
Bcps是一组抗氧化酶，属于Prx家族，广泛分布于细菌、植物和真菌中。这些蛋白质在CXXXXC基序内可以含有两个保守的半胱氨酸。第一个半胱氨酸的作用是明确的，在该蛋白质家族的所有成员中，第一个半胱氨酸是催化过氧化物的半胱氨酸，数据与IF一致。第二个半胱氨酸的功能是有争议的，需要进一步研究。在这篇文章中，我们报告的功能和结构特征的Bcp 1，古细菌的Bcp从硫磺硫化叶菌分离，它提出了两个保守的半胱氨酸残基在位置45和50。功能研究表明，这种酶使用非典型的2-Cys机制进行催化反应，其中Cys 45是过氧化物，Cys 50是解析半胱氨酸。双突变体C45 S/C50 S的X-射线结构，代表完全还原的酶状态，在2.15埃的分辨率下测定，显示类似于其他Prxs的Trx折叠。与氧化态的结构同系物的叠加，第一次提供了一个详细的结构重排的描述所需的一个成员的BCP家族进行催化反应。从这种结构分析，它出现了一个显着的构象变化，从一个完全：折叠，局部展开的形式是需要形成氧化后的分子内二硫键，根据提出的反应机制。两个残基，即Arg 53和Asp 54，其可以。在这种重新排列中发挥作用，也被确定。
Bcps constitute a group of antioxidant enzymes, belonging to the Prx family, that are widely distributed in bacteria, plants, and fungi. These proteins can contain two conserved cysteines within the CXXXXC motif Recent studies demonstrated that though. the role of the first cysteine is well defined, being the catalytic peroxidatic cysteine in all the members of this protein family, data con the IF. unction of the second cysteine are controversial and require further investigation. In this article, we report on the functional and structural characterization of Bcp1, an archaeal Bcp isolated from Sulfolobus solfataricus, which presents two conserved cysteine residues at positions 45 and 50. Functional studies revealed that this enzyme performs the catalytic reaction using an atypical 2-Cys mechanism, where Cys45 is the peroxidatic and Cys50 is the resolving cysteine. The X-ray structure of the double mutant C45S/C50S, representative of the fully reduced enzyme state, was determined at a resolution of 2.15 angstrom, showing a Trx fold similar to that of other Prxs. Superposition with a structural homologue in the oxidized state provided, for the first time, a detailed description of the structural rearrangement necessary for a member of the Bcp family to perform the catalytic reaction. From this structural analysis, it emerges that a significant conformational change from a fully :Folded, to a locally unfolded form is required to form the intramolecular disulfide bond upon oxidation, according to the proposed reaction mechanism. Two residues, namely Arg53 and Asp54, which could. play a role in this rearrangement, were also identified.