The Domain-Specific and Temperature-Dependent Protein Misfolding Phenotype of Variant Medium-Chain acyl-CoA Dehydrogenase
The Domain-Specific and Temperature-Dependent Protein Misfolding Phenotype of Variant Medium-Chain acyl-CoA Dehydrogenase
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DOI：
10.1371/journal.pone.0093852
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发表时间：
2014-04-09
期刊：
影响因子：
3.7
通讯作者：
Muntau, Ania C.
中科院分区：
文献类型：
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作者：
Jank, Johanna M.;Maier, Esther M.;Muntau, Ania C.
扩大新生儿筛查计划的实施降低了ACADM基因突变引起的中链酰基辅酶A脱氢酶缺乏症（MCADD）的死亡率和发病率。然而，这种疾病仍然是致命的。错义诱导的MCADD是一种具有分子功能丧失表型的蛋白质错误折叠疾病。在这里，我们建立了一个全面的实验装置来分析八个ACADM错义突变的结构后果。（p.Ala52Val，p.Tyr67His，p.Tyr158His，p.Arg206Cys，p.Asp266Gly，p.Lys329Glu，p.Arg334Lys，p.Arg413Ser），并将相应的蛋白质错误折叠表型与侧-链的替换。由于发热是MCADD患者代谢失代偿的关键危险因素，因此特别强调分析与热应激相关的结构和功能紊乱。基于蛋白质构象、热稳定性和动力学稳定性，MCADD中的分子表型取决于受错义诱导的构象变化影响的结构区域，其中中心β结构域特别容易发生结构紊乱和不稳定。由于ACADM突变诱导的构象紊乱的系统分类可能是评估患者临床风险的有用工具，因此我们将变体的错误折叠表型与p.Lys329Glu（K304 E）（经典重度突变）和p.Tyr67His（Y 42 H）（讨论为轻度）进行了比较。评估热应激影响的实验显示，ACADM基因突变降低了MCAD功能丧失发生的温度阈值。因此，在并发感染期间发生的温度升高显著增加了MCAD酶进一步构象紊乱和功能丧失的风险，这解释了在发热发作期间观察到的危及生命的临床过程。因此，早期和积极的退热治疗可能是挽救MCADD患者的生命。
The implementation of expanded newborn screening programs reduced mortality and morbidity in medium-chain acyl-CoA dehydrogenase deficiency (MCADD) caused by mutations in the ACADM gene. However, the disease is still potentially fatal. Missense induced MCADD is a protein misfolding disease with a molecular loss-of-function phenotype. Here we established a comprehensive experimental setup to analyze the structural consequences of eight ACADM missense mutations (p. Ala52Val, p. Tyr67His, p. Tyr158His, p. Arg206Cys, p. Asp266Gly, p. Lys329Glu, p. Arg334Lys, p. Arg413Ser) identified after newborn screening and linked the corresponding protein misfolding phenotype to the site of side-chain replacement with respect to the domain. With fever being the crucial risk factor for metabolic decompensation of patients with MCADD, special emphasis was put on the analysis of structural and functional derangements related to thermal stress. Based on protein conformation, thermal stability and kinetic stability, the molecular phenotype in MCADD depends on the structural region that is affected by missense-induced conformational changes with the central beta-domain being particularly prone to structural derangement and destabilization. Since systematic classification of conformational derangements induced by ACADM mutations may be a helpful tool in assessing the clinical risk of patients, we scored the misfolding phenotype of the variants in comparison to p. Lys329Glu (K304E), the classical severe mutation, and p. Tyr67His (Y42H), discussed to be mild. Experiments assessing the impact of thermal stress revealed that mutations in the ACADM gene lower the temperature threshold at which MCAD loss-of-function occurs. Consequently, increased temperature as it occurs during intercurrent infections, significantly increases the risk of further conformational derangement and loss of function of the MCAD enzyme explaining the life-threatening clinical courses observed during fever episodes. Early and aggressive antipyretic treatment thus may be life-saving in patients suffering from MCADD.