Murata Christina E, Goldberg Daniel E
Howard Hughes Medical Institute, Washington University, Department of Molecular Microbiology, St. Louis, Missouri 63110, USA.
J Biol Chem. 2003 Sep 26;278(39):38022-8. doi: 10.1074/jbc.M306842200. Epub 2003 Jul 22.
The malaria parasite Plasmodium falciparum degrades host cell hemoglobin within an acidic food vacuole. The metalloprotease falcilysin has previously been identified as an important component of this catabolic process. Using random peptide substrate analysis, we confirm that recombinant falcilysin is highly active at acidic pH, consistent with its role in hemoglobin degradation. Unexpectedly, the enzyme is also robustly active at neutral pH, but with a substantially different substrate specificity. Imaging studies confirm the location of falcilysin in the food vacuole and reveal association with vesicular structures elsewhere within the parasite. These data suggest that falcilysin may have an expanded role beyond globin catabolism and may function as two different proteases in its two locations.
疟原虫恶性疟原虫在酸性食物泡内降解宿主细胞血红蛋白。金属蛋白酶疟原虫溶素先前已被确定为这一分解代谢过程的重要组成部分。通过随机肽底物分析，我们证实重组疟原虫溶素在酸性pH下具有高活性，与其在血红蛋白降解中的作用一致。出乎意料的是，该酶在中性pH下也具有很强的活性，但底物特异性有很大不同。成像研究证实了疟原虫溶素在食物泡中的位置，并揭示其与寄生虫体内其他部位的囊泡结构有关联。这些数据表明，疟原虫溶素可能在球蛋白分解代谢之外具有扩展作用，并可能在其两个位置作为两种不同的蛋白酶发挥作用。
