Living species inhabiting ocean deeps must adapt to high hydrostatic pressure. This adaptation, which must enable functioning under conditions of promoted protein hydration, is especially important for proteins such as cytochromes P450 that exhibit functionally important hydration–dehydration dynamics. Here we study the interactions of substrates with cytochrome P450-SS9, a putative fatty acid hydroxylase from the piezophilic bacterium Photobacterium profundum SS9, and characterize the protein's barotropic properties. Comparison of P450-SS9 with cytochrome P450BM-3, a mesophilic fatty acid hydroxylase, suggests that P450-SS9 is characterized by severely confined accessibility and low water occupancy of the active site. This feature may reveal a mechanism for the structural adaptation of the piezophilic enzyme. We also demonstrate that saturated and unsaturated fatty acids exert opposite effects on solvent accessibility and hydration of the active site. Modulation of the protein conformation by fatty acids is hypothesized to have an important physiological function in the piezophile.

中文翻译：

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限制水进入来自嗜压细菌深底光杆菌的细胞色素 P450 的活性位点

居住在海洋深处的生物必须适应高静水压力。这种适应必须能够在促进蛋白质水合作用的条件下发挥作用，对于诸如细胞色素 P450 等具有重要功能的水合作用-脱水动力学的蛋白质尤其重要。在这里，我们研究了底物与细胞色素 P450-SS9（一种来自嗜压细菌 Photobacterium profundum SS9 的假定脂肪酸羟化酶）的相互作用，并表征了蛋白质的正压特性。P450-SS9 与细胞色素 P450BM-3（一种嗜温脂肪酸羟化酶）的比较表明，P450-SS9 的特点是活性位点的可及性严重受限和含水率低。这一特征可能揭示了亲压酶结构适应的机制。我们还证明饱和和不饱和脂肪酸对活性部位的溶剂可及性和水合作用产生相反的影响。假设脂肪酸对蛋白质构象的调节在亲压电体中具有重要的生理功能。