A Purple Cupredoxin from Nitrosopumilus maritimus Containing a Mononuclear Type 1 Copper Center with an Open Binding Site
A Purple Cupredoxin from Nitrosopumilus maritimus Containing a Mononuclear Type 1 Copper Center with an Open Binding Site
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DOI：
10.1021/jacs.5b13128
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发表时间：
2016-05-25
影响因子：
15
通讯作者：
Lu, Yi
中科院分区：
文献类型：
--
作者：
Hosseinzadeh, Parisa;Tian, Shiliang;Lu, Yi
单核细胞铜氧还蛋白通常含有一个配位饱和的1型铜（T1 Cu）中心，仅作为电子载体。在这里，我们报告了一个铜氧还蛋白分离硝化古菌Nitrosopumilus maritimus SCM 1，称为Nmar 1307，它包含一个T1铜中心与一个开放的结合位点含有水。由于在紫外-可见电子光谱中在413 nm（1880 M-1 cm（-1））和558 nm（2290 M-1 cm（-1））附近的强吸收，其显示深紫色。EPR研究表明，该蛋白质含有两种几乎相等的Cu（II）物种，一种接近轴向，超精细常数A（平行于）= 98 x 10（-4）cm（-1），另一种更菱形，具有较小的值69 x 10（-4）cm（-1）。在1.6埃分辨率下的X射线晶体结构证实，它含有一个Cu原子，在三角平面中由两个His和一个Cys配位，轴向H2O在2.25埃。紫外-可见吸收和EPR光谱研究表明，Nmar 1307可以氧化NO为亚硝酸盐，这是由于高还原电位（354 mV vs SHE）的铜网站的活动。这些结果表明，单核铜氧还蛋白可以具有广泛的结构特征，包括含有水的开放结合位点，使得这类蛋白质更加通用。
Mononuclear cupredoxin proteins usually contain a coordinately saturated type 1 copper (T1Cu) center and function exclusively as electron carriers. Here we report a cupredoxin isolated from the nitrifying archaeon Nitrosopumilus maritimus SCM1, called Nmar1307, that contains a T1Cu center with an open binding site containing water. It displays a deep purple color due to strong absorptions around 413 nm (1880 M-1 cm(-1)) and 558 nm (2290 M-1 cm(-1)) in the UV-vis electronic spectrum. EPR studies suggest the protein contains two Cu(II) species of nearly equal population, one nearly axial, with hyperfine constant A(parallel to) = 98 x 10(-4) cm(-1), and another more rhombic, with a smaller value of 69 x 10(-4) cm(-1). The X-ray crystal structure at 1.6 angstrom resolution confirms that it contains a Cu atom coordinated by two His and one Cys in a trigonal plane, with an axial H2O at 2.25 angstrom. Both UV-vis absorption and EPR spectroscopic studies suggest that the Nmar1307 can oxidize NO to nitrite, an activity that is attributable to the high reduction potential (354 mV vs SHE) of the copper site. These results suggest that mononuclear cupredoxins can have a wide range of structural features, including an open binding site containing water, making this class of proteins even more versatile.