Covalent blocking of fibril formation and aggregation of intracellular amyloidgenic proteins by transglutaminase-catalyzed intramolecular cross-linking
Covalent blocking of fibril formation and aggregation of intracellular amyloidgenic proteins by transglutaminase-catalyzed intramolecular cross-linking
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DOI：
10.1021/bi047722d
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发表时间：
2005-02-15
期刊：
影响因子：
2.9
通讯作者：
Ikura, K
中科院分区：
文献类型：
--
作者：
Konno, T;Morii, T;Ikura, K
已经提出两种不同类型的物理键合涉及患有神经退行性疾病（诸如阿尔茨海默病、帕金森病和多聚谷氨酰胺疾病）的患者的神经元内含物的形成。一种是稳定淀粉样蛋白型纤维聚集体的非共价键合，另一种是由组织转氨酶催化的共价交联。交联被细分为分子间和分子内交联。很少有人注意到分子内交联的病理作用。为了阐明分子内交联和淀粉样蛋白型原纤维形成之间可能的相互作用，我们在组织转氨酶存在下对三种细胞内淀粉样蛋白（tau蛋白，α-突触核蛋白和截短的酵母朊病毒Sup 35的结构域）进行了体外聚集分析。使用包括硫磺素T结合和质谱法的技术在低浓度的蛋白质中进行分析。结果表明，淀粉样蛋白型原纤维的形成强烈抑制由transmartaminase催化的分子内交联，这阻止了成核和纤维延伸步骤的淀粉样蛋白的形成。远紫外CD光谱表明，交联轻微改变了蛋白质的骨架构象。很可能是分子内交联所施加的构象限制损害了淀粉样蛋白的有序组装。非淀粉样蛋白型聚集也被抑制的分子内交联。根据这些结果，我们提出组织转氨酶是一种蛋白质聚集的调节剂，可以对神经元中的纤维沉积起防御作用。
Two different types of physical bonding have been proposed to involve in the formation of neuronal inclusions of patients with neurodegenerative diseases such as Alzheimer's, Parkinson's, and polyglutamine diseases. One is the noncovalent bonding that stabilizes the amyloid-type fibrous aggregates, and the other is the covalent cross-linking catalyzed by tissue transglutaminase. The cross-linking is subdivided into the inter- and intramolecular cross-linking. Little attention has been paid to the pathological roles of the intramolecular cross-linking. To elucidate the possible interplay between the intramolecular cross-linking and the amyloid-type fibril formation, we performed an in vitro aggregation analysis of three intracellular amyloidgenic proteins (a domain of tau protein, alpha-synuclein, and truncated yeast prion Sup35) in the presence of tissue transglutaminase. The analysis was performed in low concentrations of the proteins using techniques including thioflavin T binding and mass spectrometry. The results demonstrated that the amyloid-type fibril formation was strongly inhibited by the transglutaminase-catalyzed intramolecular cross-linking, which blocked both the nucleation and the fiber extension steps of the amyloid formation. Far-UV CD spectroscopy indicated that the cross-linking slightly altered the backbone conformation of the proteins. It is likely that conformational restriction imposed by the intramolecular cross-links has impaired the ordered assembly of the amyloidgenic proteins. Nonamyloid type aggregation was also suppressed by the intramolecular cross-links. On the basis of the results, we proposed that tissue transglutaminase is a modulator for the protein aggregation and can act defensively against the fibril deposition in neurons.