Structural basis for unique mechanisms of folding and hemoglobin binding by a malarial protease
Structural basis for unique mechanisms of folding and hemoglobin binding by a malarial protease
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DOI：
10.1073/pnas.0600489103
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发表时间：
2006-08-01
影响因子：
11.1
通讯作者：
McKerrow, James H.
中科院分区：
文献类型：
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作者：
Wang, Stephanie X.;Pandey, Kailash C.;McKerrow, James H.
Falcipain-2（FP 2）是恶性疟原虫的主要半胱氨酸蛋白酶，是一种血红蛋白酶，是一种很有前途的药物靶点。在这里，我们报告的晶体结构的FP 2与蛋白酶抑制剂，半胱氨酸蛋白酶抑制剂。FP 2结构揭示了两个先前未描述的半胱氨酸蛋白酶结构基序，命名为FP 2（鼻）和FP 2（臂），除了活性位点的细节，这将有助于集中抑制剂设计。与大多数半胱氨酸蛋白酶不同，FP 2不需要前结构域，而只需要短的FP 2（鼻）基序来正确折叠并获得催化活性。我们的结构和诱变数据表明，这种独特的机制的分子基础，通过突出的功能作用，两个酪氨酸内FP 2（鼻子）和保守的Glu外，这个基序。FP 2臂基序是血红蛋白酶活性所必需的。该结构揭示了FP 2（臂）周围的地形特征和负电荷簇，表明它可能作为血红蛋白结合的外位点。与FP 2（鼻子）和FP 2（手臂）相似的基序仅在相关的疟原虫蛋白酶中发现，这表明它们赋予疟疾特异性功能。
Falcipain-2 (FP2), the major cysteine protease of the human malaria parasite Plasmodium falciparum, is a hemoglobinase and promising drug target. Here we report the crystal structure of FP2 in complex with a protease inhibitor, cystatin. The FP2 structure reveals two previously unclescribed cysteine protease structural motifs, designated FP2(nose) and FP2(arm), in addition to details of the active site that will help focus inhibitor design. Unlike most cysteine proteases, FP2 does not require a prodomain but only the short FP2(nose) motif to correctly fold and gain catalytic activity. Our structure and mutagenesis data suggest a molecular basis for this unique mechanism by highlighting the functional role of two Tyr within FP2(nose) and a conserved Glu outside this motif. The FP2arm motif is required for hemoglobinase activity. The structure reveals topographic features and a negative charge cluster surrounding FP2(arm) that suggest it may serve as an exo-site for hemoglobin binding. Motifs similar to FP2(nose) and FP2(arm) are found only in related plasmodial proteases, suggesting that they confer malaria-specific functions.