Waller Karena L, Stubberfield Lisa M, Dubljevic Valentina, Buckingham Donna W, Mohandas Narla, Coppel Ross L, Cooke Brian M
Department of Microbiology, Monash University, VIC 3800, Australia.
Biochim Biophys Acta. 2010 May;1798(5):861-71. doi: 10.1016/j.bbamem.2010.01.018. Epub 2010 Feb 2.
Intra-erythrocytic Plasmodium falciparum malaria parasites synthesize and export numerous proteins into the red blood cell (RBC) cytosol, where some bind to the RBC membrane skeleton. These interactions are responsible for the altered antigenic, morphological and functional properties of parasite-infected red blood cells (IRBCs). Plasmodium falciparum protein 332 (Pf332) is a large parasite protein that associates with the membrane skeleton and who's function has recently been elucidated. Using recombinant fragments of Pf332 in in vitro interaction assays, we have localised the specific domain within Pf332 that binds to the RBC membrane skeleton to an 86 residue sequence proximal to the C-terminus of Pf332. We have shown that this region partakes in a specific and saturable interaction with actin (K(d)=0.60 microM) but has no detectable affinity for spectrin. The only exported malaria protein previously known to bind to actin is PfEMP3 but here we demonstrate that there is no competition for actin-binding between PfEMP3 and Pf332, suggesting that they bind to different target sequences in actin.
恶性疟原虫疟疾寄生虫在红细胞（RBC）胞质溶胶中合成并输出大量蛋白质，其中一些与RBC膜骨架结合。这些相互作用导致了寄生虫感染的红细胞（IRBC）抗原性、形态和功能特性的改变。恶性疟原虫蛋白332（Pf332）是一种与膜骨架相关的大型寄生虫蛋白，其功能最近已得到阐明。在体外相互作用试验中使用Pf332的重组片段，我们已将Pf332中与RBC膜骨架结合的特定结构域定位到Pf332 C末端附近的一个86个残基的序列。我们已经表明，该区域与肌动蛋白发生特异性和饱和性相互作用（K(d)=0.60 microM），但对血影蛋白没有可检测到的亲和力。先前已知的唯一与肌动蛋白结合的输出性疟疾蛋白是PfEMP3，但在这里我们证明PfEMP3和Pf332之间不存在对肌动蛋白结合的竞争，这表明它们与肌动蛋白中的不同靶序列结合。
