Characterization of zebrafish neuroglobin and cytoglobins 1 and 2: Zebrafish cytoglobins provide insights into the transition from six-coordinate to five-coordinate globins
Characterization of zebrafish neuroglobin and cytoglobins 1 and 2: Zebrafish cytoglobins provide insights into the transition from six-coordinate to five-coordinate globins
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DOI：
10.1016/j.niox.2015.12.004
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发表时间：
2016-02-01
影响因子：
3.9
通讯作者：
Tejero, Jesus
中科院分区：
文献类型：
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作者：
Corti, Paola;Ieraci, Matthew;Tejero, Jesus
脑红蛋白(NGb)和细胞球蛋白(Cygb)是两种生理功能未知的六配位血红素蛋白。虽然对哺乳动物蛋白质的研究已经阐明了NGB和Cygb的生物物理学方面，并指出了潜在的功能，但非哺乳动物NGB和Cygb的性质在很大程度上还没有确定。我们在大肠杆菌中表达了重组斑马鱼蛋白NGB、Cygb1和Cygb2，并对它们的亚硝酸盐还原速率、光谱性质、自氧化速率常数、氧化还原电位和脂质结合特性进行了表征。这三种斑马鱼蛋白可以催化亚硝酸盐还原为一氧化氮，反应速率常数范围很大。(Ngb，0.68+/-0.04M-1 S(-1)；Cygb1，28.6+/-3.1M-1 S(-1)；Cygb2，0.94+/-0.18M-1 S(-1))。我们观察到斑马鱼NGb和Cygb2与人类NGb和Cygb具有类似的光谱特征，与六坐标血红素一致，而出人意料的是Cygb1具有五坐标血红素，自氧化较慢，总体上具有更类似于氧运输蛋白的性质。与可能的氧载体和亚硝酸还原酶的作用一致，我们在斑马鱼血液中检测到Cygb1的mRNA转录，但没有检测到Cygb2或NGB。与人类Cygb不同，这两种斑马鱼球蛋白都不能以高亲和力结合油酸。这一发现表明，脂质结合可能是后来进化过程中获得的特征，而不是细胞球蛋白的祖先属性。总之，我们的结果揭示了斑马鱼球蛋白意想不到的特性，并揭示了细胞球蛋白在血红素球蛋白从六配位氧载体和亚硝酸盐还原酶向五配位氧载体和亚硝酸盐还原酶的转变中的关键作用。(C)2015 Elsevier Inc.保留所有权利。
Neuroglobin (Ngb) and cytoglobin (Cygb) are two six-coordinate heme proteins of unknown physiological function. Although studies on the mammalian proteins have elucidated aspects of Ngb and Cygb biophysics and indicated potential functions, the properties of non-mammalian Ngbs and Cygbs are largely uncharacterized. We have expressed the recombinant zebrafish proteins Ngb, Cygb1, and Cygb2 in Escherichia coli and characterized their nitrite reduction rates, spectral properties, autoxidation rate constants, redox potentials and lipid binding properties. The three zebrafish proteins can catalyze the reduction of nitrite to nitric oxide with a broad range of reaction rate constants. (Ngb, 0.68 +/- 0.04 M-1 s(-1); Cygb1, 28.6 +/- 3.1 M-1 s(-1); Cygb2, 0.94 +/- 0.18 M-1 s(-1)). We observe that zebrafish Ngb and Cygb2 have comparable spectral features to those of human Ngb and Cygb, consistent with a six coordinate heme, whereas unexpectedly Cygb1 has a five-coordinate heme, a slower autoxidation and in general has properties more akin to oxygen transport proteins. In agreement with a possible oxygen carrier and nitrite reductase role, we detect mRNA transcript for Cygb1 but not Cygb2 or Ngb in zebrafish blood. Unlike human Cygb, neither of the zebrafish globins binds oleic acid with high affinity. This finding suggests that lipid binding may be a trait acquired later during evolution and not an ancestral property of cytoglobins. Altogether, our results uncover unexpected properties of zebrafish globins and reveal the pivotal role of cytoglobins in the transition of heme globins from six-coordinate to five-coordinate oxygen carriers and nitrite reductases. (C) 2015 Elsevier Inc. All rights reserved.