BACKGROUND Temperature exerts a strong influence on protein evolution: species living in thermally distinct environments often exhibit adaptive differences in protein structure and function. However, previous research on protein temperature adaptation has focused on small numbers of proteins and on proteins adapted to extreme temperatures. Consequently, less is known about the types and quantity of evolutionary change that occurs to proteins when organisms adapt to small shifts in environmental temperature. In this study, these uncertainties were addressed by developing software that enabled comparison of structural changes associated with temperature adaptation (hydrogen bonding, salt bridge formation, and amino acid use) among large numbers of proteins from warm- and cold-adapted species of marine mussels, Mytilus galloprovincialis and Mytilus trossulus, respectively. RESULTS Small differences in habitat temperature that characterize the evolutionary history of Mytilus mussels were sufficient to cause protein structural changes consistent with temperature adaptation. Hydrogen bonds and salt bridges that increase stability and protect against heat-induced denaturation were more abundant in proteins from warm-adapted M. galloprovincialis compared with proteins from cold-adapted M. trossulus. These structural changes were related to deviations in the use of polar and charged amino acids that facilitate formation of hydrogen bonds and salt bridges within proteins, respectively. Enzymes, in particular those within antioxidant and cell death pathways, were over-represented among proteins with the most hydrogen bonds and salt bridges in warm-adapted M. galloprovincialis. Unlike extremophile proteins, temperature adaptation in Mytilus proteins did not involve substantial changes in the number of hydrophobic or large volume amino acids, nor in the content of glycine or proline. CONCLUSIONS Small shifts in organism temperature tolerance, such as that needed to cope with climate warming, may result from structural and functional changes to a small percentage of the proteome. Proteins in which function is dependent on large conformational change, notably enzymes, may be particularly sensitive to temperature perturbation and represent foci for natural selection. Protein temperature adaptation can occur through different types and frequencies of structural change, and adaptive mechanisms used to cope with small shifts in habitat temperature appear different from mechanisms used to retain protein function at temperature extremes.

中文翻译：

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蛋白质结构变化的高通量定量揭示了贻贝贻贝中温度适应的潜在机制。

背景技术温度对蛋白质进化有很大影响：生活在热不同环境中的物种通常在蛋白质结构和功能上表现出适应性差异。然而，先前关于蛋白质温度适应性的研究集中于少量蛋白质和适应极端温度的蛋白质。因此，当生物体适应环境温度的微小变化时，蛋白质发生的进化变化的类型和数量所知甚少。在这项研究中，这些不确定性通过开发软件来解决，该软件能够比较来自温和冷的海洋贻贝物种的大量蛋白质中与温度适应性相关的结构变化（氢键，盐桥形成和氨基酸使用） ，鸡没食子菌和trossulus菌。结果栖息地温度的微小差异足以说明贻贝贻贝的进化史，足以引起与温度适应相一致的蛋白质结构变化。与来自冷适应的M. trossulus的蛋白质相比，来自温适应的M. galloprovincialis的蛋白质具有更多的氢键和盐桥，可增加稳定性并防止热诱导的变性。这些结构变化与极性氨基酸和带电荷氨基酸的使用偏向有关，分别促进了蛋白质中氢键和盐桥的形成。酶，尤其是抗氧化剂和细胞死亡途径中的酶，在温暖适应的M中具有最多氢键和盐桥的蛋白质中含量过高。Galloprovincialis。与极端微生物蛋白不同，Mytilus蛋白的温度适应性不涉及疏水性或大量氨基酸的数量的实质性变化，也不涉及甘氨酸或脯氨酸的含量的重大变化。结论机体温度耐受性的微小变化（例如应对气候变暖所需的温度变化）可能是由于蛋白质组中一小部分的结构和功能发生了变化。功能取决于大的构象变化的蛋白质，特别是酶，可能对温度扰动特别敏感，并代表自然选择的重点。蛋白质温度适应可以通过不同类型和频率的结构变化发生，