Jeong Jong-Jin, Kumar Ajay, Hanada Toshihiko, Seo Pil-Soo, Li Xuerong, Hanspal Manjit, Chishti Athar H
Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL 60561, USA.
Blood Cells Mol Dis. 2006 May-Jun;36(3):429-35. doi: 10.1016/j.bcmd.2006.02.003. Epub 2006 Apr 3.
The gene for malaria parasite cysteine protease falcipain-2B has been isolated from the Plasmodium falciparum genomic DNA. Falcipain-2B gene is located adjacent to the falcipain-2A gene on chromosome 11, and the two enzymes show extensive sequence identity at the amino acid level. Using reverse transcribed polymerase chain reaction (RT-PCR), the transcript of falcipain-2B was detected at the trophozoite stage of P. falciparum in human erythrocytes. Recombinant falcipain-2B protein expressed in bacteria exhibits protease activity as established by the cleavage of fluorescent peptide substrate as well as in-gel gelatin zymography. Importantly, the recombinant falcipain-2B cleaved host ankyrin but not protein 4.1 as assessed by the erythrocyte inside-out-vesicle assay in vitro. Notwithstanding its predicted hemoglobinase function, the P. falciparum falcipain-2B may contribute and orchestrate selective proteolytic events during the exit of malaria parasite from human red blood cells.
疟原虫半胱氨酸蛋白酶恶性疟原虫蛋白酶-2B的基因已从恶性疟原虫基因组DNA中分离出来。恶性疟原虫蛋白酶-2B基因位于11号染色体上恶性疟原虫蛋白酶-2A基因的旁边，这两种酶在氨基酸水平上显示出广泛的序列同一性。使用逆转录聚合酶链反应（RT-PCR），在人红细胞内恶性疟原虫的滋养体阶段检测到了恶性疟原虫蛋白酶-2B的转录本。在细菌中表达的重组恶性疟原虫蛋白酶-2B蛋白表现出蛋白酶活性，这通过荧光肽底物的切割以及凝胶内明胶酶谱法得以证实。重要的是，通过体外红细胞内翻囊泡试验评估，重组恶性疟原虫蛋白酶-2B可切割宿主锚蛋白，但不能切割蛋白4.1。尽管其具有预测的血红蛋白酶功能，但恶性疟原虫恶性疟原虫蛋白酶-2B可能在疟原虫从人类红细胞中逸出的过程中促成并协调选择性蛋白水解事件。
