Multiple cathepsin B isoforms in schistosomula of Trichobilharzia regenti:: identification, characterisation and putative role in migration and nutrition
Multiple cathepsin B isoforms in schistosomula of Trichobilharzia regenti:: identification, characterisation and putative role in migration and nutrition
复制标题
DOI：
10.1016/j.ijpara.2005.02.018
复制
发表时间：
2005-07-01
影响因子：
4
通讯作者：
Caffrey, CR
中科院分区：
文献类型：
--
作者：
Dvorák, J;Delcroix, M;Caffrey, CR
在寄生虫中，雷根毛毕吸虫在最终鸟类宿主的鼻腔中居住之前，显示出通过外周和中枢神经系统的不寻常的迁移。迁移导致鸟类和实验感染小鼠的组织退化和神经运动功能障碍。虽然青少年有一个发达的肠道，肽酶阐述，可能有利于营养和迁移是未知的。这在很大程度上是由于难以隔离大量迁移的幼虫。我们已经确定和特点的主要33 kDa的组织蛋白酶B样半胱氨酸内肽酶的提取物中的迁移adiposomula使用荧光肽基底物具有高消光系数和不可逆的亲和力标签。使用简并PCR和cDNA末端的快速扩增方案从第一链拟南芥cDNA鉴定称为TrCB 1.1-TrCB 1.6的肽酶同种型。最高的序列同源性是与所描述的曼氏血吸虫和日本血吸虫组织蛋白酶B1。两种异构体（TrCB 1.5和1.6）编码pupidine失活酶，因为催化半胱氨酸被甘氨酸取代。另外两种异构体TrCB 1.1和1.4在巴斯德毕赤酵母中作为酶原功能性表达。特异性的多克隆抗体定位的肽酶专门在肠道的童虫和反应的33 kDa的蛋白质在蠕虫提取物。TrCB 1.1酶原不能催化自身的活化，但能被S.曼氏天冬酰胺酰内肽酶（SmAE aka. S. mansoni legumain）。相反，TrCB 1.4酶原自激活，但抵抗SmAE的作用。这两种活化的亚型显示不同的pH依赖性特异性曲线与肽基底物。此外，这两种亚型降解髓鞘碱性蛋白，神经组织的主要蛋白质成分，但对血红蛋白的效率低下，从而支持适应T regenti肠肽酶寄生宿主神经组织。(c)2005年澳大利亚寄生虫学学会有限公司由爱思唯尔有限公司出版。保留所有权利。
Among schistosomatids, Trichobilharzia regenti, displays an unusual migration through the peripheral and central nervous system prior to residence in the nasal cavity of the definitive avian host. Migration causes tissue degradation and neuromotor dysfunction both in birds and experimentally infected mice. Although schistosomula have a well-developed gut, the peptidases elaborated that might facilitate nutrition and migration are unknown. This is, in large part, due to the difficulty in isolating large numbers of migrating larvae. We have identified and characterised the major 33 kDa cathepsin B-like cysteine endopeptidase in extracts of migrating schistosomula using fluorogenic peptidyl substrates with high extinction coefficients and irreversible affinity-labels. From first strand schistosomula cDNA, degenerate PCR and Rapid Amplification of cDNA End protocols were used to identify peptidase isoforms termed TrCB1.1-TrCB1.6. Highest sequence homology is to the described Schistosoma mansoni and Schistosoma japonicum cathepsins B1. Two isoforms (TrCB1.5 and 1.6) encode putatively inactive enzymes as the catalytic cysteine is substituted by glycine. Two other isoforms, TrCB1.1 and 1.4, were functionally expressed as zymogens in Pichia pastoris. Specific polyclonal antibodies localised the peptidases exclusively in the gut of schistosomula and reacted with a 33 kDa protein in worm extracts. TrCB1.1 zymogen was unable to catalyse its own activation, but was trans-processed and activated by S. mansoni asparaginyl endopeptidase (SmAE aka. S. mansoni legumain). In contrast, TrCB1.4 zymogen auto-activated, but was resistant to the action of SmAE. Both activated isoforms displayed different pH-dependent specificity profiles with peptidyl substrates. Also, both isoforms degraded myelin basic protein, the major protein component of nervous tissue, but were inefficient against hemoglobin, thus supporting the adaptation of T regenti gut peptidases to parasitism of host nervous tissue. (c) 2005 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.