Antithrombin Murcia (K241E) causing antithrombin deficiency: a possible role for altered glycosylation
Antithrombin Murcia (K241E) causing antithrombin deficiency: a possible role for altered glycosylation
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DOI：
10.3324/haematol.2009.015487
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发表时间：
2010-08-01
期刊：
影响因子：
--
通讯作者：
Corral, Javier
中科院分区：
文献类型：
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作者：
Martinez-Martinez, Irene;Ordonez, Adriana;Corral, Javier
背景对SERPINC1基因突变的鉴定揭示了抗凝血酶缺乏症的不同机制。缺失和无义突变与I型缺乏症相关。设计与方法我们研究了一种新的天然突变K241E的分子、生化、蛋白质组学和糖学特性。结果突变导致抗凝血活性显著降低，主要是由于肝素亲和力的降低和静电势的改变，这可能解释了突变蛋白在没有肝素的情况下与目标蛋白酶形成络合物的能力受损。质谱学和糖学分析证实，突变蛋白中的相对分子质量增加了800Da，这可能是由于核心-岩藻糖基化，导致肝素亲和力的丧失。此外，这种突变的携带者也有一个微小的突变亚型，仍然遵循正常的糖基化反应，保持了与野生型a-抗凝血酶相似的肝素亲和力，以及一定的抗凝血活性，这可能解释了携带这种突变的患者较轻的血栓形成风险。重组K241E抗凝血酶分子也观察到了类似的结果。结论我们的数据表明，通过间接影响一个自然变异体的糖基化，参与了抗凝血酶II型缺乏症的新机制。还需要更多的研究来证实这一假设。
BackgroundIdentification of mutations in the SERPINC1 gene has revealed different mechanisms responsible for antithrombin deficiency. Deletions and nonsense mutations associate with type I deficiency. Certain missense mutations cause type II deficiency by affecting the heparin binding site or the reactive center loop, while others result in type I deficiency by intracellular retention or RNA instability.Design and MethodsWe studied the molecular, biochemical, proteomic and glycomic characterization of a new natural mutant (K241E) that may be classified as pleiotropic.ResultsThe mutation caused a significant decrease in the anticoagulant activity mainly due to a reduced heparin affinity and a modification of the electrostatic potential that might explain the impaired ability of the mutant protein to form complexes with the target protease in the absence of heparin. Mass spectrometry and glycomic analyses confirmed an increased molecular weight of 800 Da in the mutant protein possibly due to core-fucosylation, provoking the loss of heparin affinity. Additionally, carriers of this mutation also have a minor mutant isoform that still followed normal glycosylation, retaining similar heparin affinity to wild-type a-antithrombin, and certain anticoagulant activity, which may explain the milder thrombotic risk of patients carrying this mutation. Similar results were observed using recombinant K241E antithrombin molecules.ConclusionsOur data suggest a new mechanism involved in antithrombin type II deficiency by indirectly affecting the glycosylation of a natural variant. Additional studies are required to confirm this hypothesis.