Yuan Taolin, Kumar Surinder, Skinner Mary E, Victor-Joseph Ryan, Abuaita Majd, Keijer Jaap, Zhang Jessica, Kunkel Thaddeus J, Liu Yanghan, Petrunak Elyse M, Saunders Thomas L, Lieberman Andrew P, Stuckey Jeanne A, Neamati Nouri, Al-Murshedi Fathiya, Alfadhel Majid, Spelbrink Johannes N, Rodenburg Richard, de Boer Vincent C J, Lombard David B
Human and Animal Physiology, Wageningen University, De Elst 1, Wageningen, the Netherlands.
Department of Pathology & Laboratory Medicine, Miller School of Medicine, and Sylvester Comprehensive Cancer Center, University of Miami, Miami, FL 33136, USA.
iScience. 2024 May 15;27(6):109991. doi: 10.1016/j.isci.2024.109991. eCollection 2024 Jun 21.
SIRT5 is a sirtuin deacylase that removes negatively charged lysine modifications, in the mitochondrial matrix and elsewhere in the cell. In benign cells and mouse models, under basal conditions, the phenotypes of SIRT5 deficiency are quite subtle. Here, we identify two homozygous variants in patients suspected to have mitochondrial disease. Both variants, P114T and L128V, are associated with reduced SIRT5 protein stability and impaired biochemical activity, with no evidence of neomorphic or dominant negative properties. The crystal structure of the P114T enzyme was solved and shows only subtle deviations from wild-type. Via CRISPR-Cas9, we generated a mouse model that recapitulates the human P114T mutation; homozygotes show reduced SIRT5 levels and activity, but no obvious metabolic abnormalities, neuropathology, or other gross phenotypes. We conclude that these human variants most likely represent severe hypomorphs, but are likely not by themselves the primary pathogenic cause of the neuropathology observed in the patients.
SIRT5是一种去乙酰化酶，可去除线粒体基质和细胞其他部位带负电荷的赖氨酸修饰。在良性细胞和小鼠模型中，在基础条件下，SIRT5缺乏的表型相当微妙。在此，我们在疑似患有线粒体疾病的患者中鉴定出两个纯合变体。这两个变体，P114T和L128V，均与SIRT5蛋白稳定性降低和生化活性受损有关，没有新功能或显性负性特性的证据。解析了P114T酶的晶体结构，结果显示其与野生型仅有细微偏差。通过CRISPR-Cas9，我们构建了一个重现人类P114T突变的小鼠模型；纯合子显示SIRT5水平和活性降低，但没有明显的代谢异常、神经病理学或其他明显表型。我们得出结论，这些人类变体很可能代表严重的亚效等位基因，但它们本身可能不是患者中观察到的神经病理学的主要致病原因。
