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首页> 外文期刊>Journal of Molecular Biology >Functional evolution of ribonuclease inhibitor: Insights from birds and reptiles
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Functional evolution of ribonuclease inhibitor: Insights from birds and reptiles

机译：核糖核酸酶抑制剂的功能演化：鸟类和爬行动物的见解

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摘要

Ribonuclease inhibitor (RI) is a conserved protein of the mammalian cytosol. RI binds with high affinity to diverse secretory ribonucleases (RNases) and inhibits their enzymatic activity. Although secretory RNases are found in all vertebrates, the existence of a non-mammalian RI has been uncertain. Here, we report on the identification and characterization of RI homologs from chicken and anole lizard. These proteins bind to RNases from multiple species but exhibit much greater affinity for their cognate RNases than for mammalian RNases. To reveal the basis for this differential affinity, we determined the crystal structure of mouse, bovine, and chicken RI·RNase complexes to a resolution of 2.20, 2.21, and 1.92 ?, respectively. A combination of structural, computational, and bioinformatic analyses enabled the identification of two residues that appear to contribute to the differential affinity for RNases. We also found marked differences in oxidative instability between mammalian and non-mammalian RIs, indicating evolution toward greater oxygen sensitivity in RIs from mammalian species. Taken together, our results illuminate the structural and functional evolution of RI, along with its dynamic role in vertebrate biology.
机译：核糖核酸酶抑制剂（RI）是哺乳动物细胞源的保守蛋白质。 RI与多种亲和力结合，对不同的分泌核糖核酸酶（RNases）抑制其酶活性。虽然在所有脊椎动物中发现了分泌物RNases，但非哺乳动物RI的存在是不确定的。在这里，我们报告了鸡肉和αole蜥蜴的RI同源物的鉴定和表征。这些蛋白质与来自多种物种的RNase结合，但对其同源RNase具有比哺乳动物RNase的更大的亲和力。为了揭示这种差异亲和力的基础，我们确定了小鼠，牛和鸡Ri·RNase复合物的晶体结构，分别为2.20,2.21和1.92的分辨率。结构，计算和生物信息化分析的组合使得能够鉴定两种残留物，该残基似乎有助于对RNases的差异亲和力。我们还发现了哺乳动物和非哺乳动物RIS之间的氧化不稳定性的显着差异，表明来自哺乳动物物种的RIS较大的氧敏感性的演变。在一起，我们的结果阐明了RI的结构和功能演进，以及其在脊椎动物生物学中的动态作用。

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