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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进化：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）是哺乳动物细胞溶胶的保守蛋白。 RI以高亲和力与各种分泌型核糖核酸酶（RNase）结合，并抑制其酶促活性。尽管在所有脊椎动物中都发现了分泌性RNase，但不确定是否存在非哺乳动物RI。在这里，我们报道了从鸡和蜥蜴蜥蜴的RI同系物的鉴定和表征。这些蛋白质与多种物种的RNase结合，但对它们的同类RNase的亲和力比对哺乳动物RNase的亲和力大得多。为了揭示这种差异亲和力的基础，我们确定了小鼠，牛和鸡的RI·RNase复合物的晶体结构，其分辨率分别为2.20、2.21和1.92Ω。结构，计算和生物信息学分析的组合使得能够鉴定两个似乎有助于RNase差异亲和力的残基。我们还发现哺乳动物和非哺乳动物RI之间的氧化不稳定性存在显着差异，这表明从哺乳动物物种获得的RI朝着更高的氧敏感性发展。综上所述，我们的结果阐明了RI的结构和功能演变，以及其在脊椎动物生物学中的动态作用。

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