Specific cleavage sites on human IgG subclasses by cruzipain, the major cysteine proteinase from Trypanosoma cruzi
Specific cleavage sites on human IgG subclasses by cruzipain, the major cysteine proteinase from Trypanosoma cruzi
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DOI：
10.1016/s0166-6851(03)00139-7
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发表时间：
2003-08-11
影响因子：
1.5
通讯作者：
Goñi, F
中科院分区：
文献类型：
--
作者：
Berasain, P;Carmona, C;Goñi, F
克氏锥虫的主要半胱氨酸蛋白酶克氏锥虫蛋白酶可能具有除代谢功能外的其他生物学作用。在本报告中，我们探讨了杏仁蛋白酶与免疫系统分子的相互作用。该酶用于在不同pH值和时间下消化所有人IgG亚类。在pH 7.3时，所有亚类在铰链区都很容易分裂。免疫印迹和氨基酸序列分析显示，IgG I和IgG3片段与Fab和Fc相容，而IgG2和IgG4片段与Fab(2)和Fc相容。在所有情况下，产生的片段都可能损害特异性IgG的结合能力和效应功能。在这些切割位点，cruzipain显示出组织蛋白酶L和/或组织蛋白酶B的活性，并在P'2位置和P1的极性残基上显示出明显的Pro偏好。尽管蛋白蛋白酶在铰链内具有活性，但该酶也能切割CH2和CH3结构域之间的所有重链；产生14kda的Fc'-样片段。这些片段是阻断或饱和免疫活性细胞上Fc受体的潜在候选者。在温和的酸性pH下，cruzipain进一步降解了所有亚类的Fc， IgG4的Fd和igg1的部分Fd，并持续丧失任何抗体活性。L链显然没有受到影响。因此，木瓜蛋白酶应该能够根据所选择的亚类和环境的pH值，产生和不同的生物活性/无活性IgG片段的长度进行调节。(C) 2003 Elsevier B.V.版权所有
Cruzipain, the major cysteine proteinase of Trypanosoma cruzi, might have other biological roles than its metabolic functions. In this report, we have explored the interaction of cruzipain with molecules of the immune system. The enzyme was used to digest all human IgG subclasses at different pH values and lengths of time. At pH 7.3, all subclasses were readily split at the hinge region. Immunoblot and amino acid sequence analysis showed fragments of IgG I and IgG3 to be compatible with Fab and Fc, whereas IgG2 and IgG4 tendered Fab(2) and Fc. In all cases the fragments produced might impair the binding capacities and the effector functions of specific IgG. At these cleavage sites cruzipain displays cathepsin L and/or cathepsin B activities and shows a clear preference for Pro at the P'2 position and polar residues at P1. Despite the activity of cruzipain within the hinge, the enzyme also cleaved all heavy chains between the CH2 and CH3 domains; producing Fc'-like-fragments of 14 kDa. These fragments are potential candidates to block or saturate Fc receptors on immunocompetent cells. At mild acidic pH cruzipain produced further degradation of the Fc of all subclasses, the Fd of IgG4 and partially the Fd of IgG 1, with the consistent loss of any antibody activity. The L chains apparently were not affected. Thus, cruzipain should be able to modulate, depending on the subclass selected and the pH of the environment, the production and the length of different biologically active/inactive IgG fragments. (C) 2003 Elsevier B.V. All rights reserved.