Structure of dehaloperoxidase B at 1.58 Å resolution and structural characterization of the AB dimer from Amphitrite ornata
Structure of dehaloperoxidase B at 1.58 Å resolution and structural characterization of the AB dimer from Amphitrite ornata
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DOI：
10.1107/s0907444910004580
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发表时间：
2010-05-01
影响因子：
2.2
通讯作者：
Ghiladi, Reza A.
中科院分区：
文献类型：
--
作者：
de Serrano, Vesna;D'Antonio, Jennifer;Ghiladi, Reza A.
作为珠蛋白超家族的成员，海洋环节动物双栖动物的脱盐过氧化物酶（DHP）同工酶A和B具有血红蛋白功能，但它们也表现出与生物相关的过氧化物酶活性，能够在过氧化氢存在下将2,4,6-三卤酚转化为相应的2,6-二卤醌。本文利用x射线衍射对重组DHP B进行了全面的结构研究，包括DHP B本身和与同工酶a共结晶。细化到1.58埃分辨率的DHP B结构显示出与同工酶A相同的远端组氨酸（His55）构象灵活性，以及远端和近端氢键网络的额外变化。此外，DHP AB异源二聚体的初步表征，其AB界面的差异在a -或b -纯同型二聚体中没有观察到。DHP B的这些结构研究提供了可能与脱卤过氧化物酶催化的h2o2依赖性氧化脱卤反应的机制细节有关的见解，在分子水平上对DHP中特定残基的功能有了更清晰的描述，并有助于更好地理解珠蛋白结构-功能关系的范例。
As members of the globin superfamily, dehaloperoxidase (DHP) isoenzymes A and B from the marine annelid Amphitrite ornata possess hemoglobin function, but they also exhibit a biologically relevant peroxidase activity that is capable of converting 2,4,6-trihalophenols to the corresponding 2,6-dihaloquinones in the presence of hydrogen peroxide. Here, a comprehensive structural study of recombinant DHP B, both by itself and cocrystallized with isoenzyme A, using X-ray diffraction is presented. The structure of DHP B refined to 1.58 angstrom resolution exhibits the same distal histidine (His55) conformational flexibility as that observed in isoenzyme A, as well as additional changes to the distal and proximal hydrogen-bonding networks. Furthermore, preliminary characterization of the DHP AB heterodimer is presented, which exhibits differences in the AB interface that are not observed in the A-only or B-only homodimers. These structural investigations of DHP B provide insights that may relate to the mechanistic details of the H2O2-dependent oxidative dehalogenation reaction catalyzed by dehaloperoxidase, present a clearer description of the function of specific residues in DHP at the molecular level and lead to a better understanding of the paradigms of globin structure-function relationships.