Medina-Carmona Encarnación, Fuchs Julian E, Gavira Jose A, Mesa-Torres Noel, Neira Jose L, Salido Eduardo, Palomino-Morales Rogelio, Burgos Miguel, Timson David J, Pey Angel L
Department of Physical Chemistry, Faculty of Sciences, University of Granada, Granada, Spain.
Institute of General, Inorganic and Theoretical Chemistry, Faculty of Chemistry and Pharmacy, University of Innsbruck, Innsbruck, Austria.
Hum Mol Genet. 2017 Sep 15;26(18):3531-3544. doi: 10.1093/hmg/ddx238.
Human proteins are vulnerable towards disease-associated single amino acid replacements affecting protein stability and function. Interestingly, a few studies have shown that consensus amino acids from mammals or vertebrates can enhance protein stability when incorporated into human proteins. Here, we investigate yet unexplored relationships between the high vulnerability of human proteins towards disease-associated inactivation and recent evolutionary site-specific divergence of stabilizing amino acids. Using phylogenetic, structural and experimental analyses, we show that divergence from the consensus amino acids at several sites during mammalian evolution has caused local protein destabilization in two human proteins linked to disease: cancer-associated NQO1 and alanine:glyoxylate aminotransferase, mutated in primary hyperoxaluria type I. We demonstrate that a single consensus mutation (H80R) acts as a disease suppressor on the most common cancer-associated polymorphism in NQO1 (P187S). The H80R mutation reactivates P187S by enhancing FAD binding affinity through local and dynamic stabilization of its binding site. Furthermore, we show how a second suppressor mutation (E247Q) cooperates with H80R in protecting the P187S polymorphism towards inactivation through long-range allosteric communication within the structural ensemble of the protein. Our results support that recent divergence of consensus amino acids may have occurred with neutral effects on many functional and regulatory traits of wild-type human proteins. However, divergence at certain sites may have increased the propensity of some human proteins towards inactivation due to disease-associated mutations and polymorphisms. Consensus mutations also emerge as a potential strategy to identify structural hot-spots in proteins as targets for pharmacological rescue in loss-of-function genetic diseases.
人类蛋白质易受与疾病相关的单氨基酸替换影响，这些替换会影响蛋白质的稳定性和功能。有趣的是，一些研究表明，来自哺乳动物或脊椎动物的共有氨基酸在整合到人类蛋白质中时可以增强蛋白质稳定性。在此，我们研究人类蛋白质对疾病相关失活的高易感性与稳定氨基酸最近的进化位点特异性差异之间尚未探索的关系。通过系统发育、结构和实验分析，我们表明在哺乳动物进化过程中，几个位点上与共有氨基酸的差异导致了与疾病相关的两种人类蛋白质局部蛋白质不稳定：与癌症相关的NQO1和在I型原发性高草酸尿症中发生突变的丙氨酸：乙醛酸转氨酶。我们证明，单个共有突变（H80R）对NQO1中最常见的与癌症相关的多态性（P187S）起到疾病抑制作用。H80R突变通过局部和动态稳定其结合位点来增强FAD结合亲和力，从而使P187S重新激活。此外，我们展示了第二个抑制突变（E247Q）如何与H80R协同作用，通过蛋白质结构整体内的长程变构通讯来保护P187S多态性免于失活。我们的结果支持，共有氨基酸最近的差异可能对野生型人类蛋白质的许多功能和调节特性产生中性影响。然而，某些位点的差异可能增加了一些人类蛋白质因疾病相关突变和多态性而失活的倾向。共有突变也成为一种潜在策略，可用于识别蛋白质中的结构热点，作为功能丧失性遗传疾病药理拯救的靶点。
