Goswami A, Singh S, Redkar V D, Sharma S
Molecular Biology Unit, Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay, 400 005 India.
J Biol Chem. 1997 May 2;272(18):12138-43. doi: 10.1074/jbc.272.18.12138.
A cDNA expression clone of the human malarial parasite Plasmodium falciparum, lambdaPf4, which was reactive only to the immune sera and not to the patient sera, has recently been found to be the P. falciparum homologue of the P0 ribosomal phosphoprotein gene. A Northern analysis of the P0 gene revealed the presence of two transcripts, both present in all the different intraerythrocytic stages of the parasite life cycle. A 138-base pair amino-terminal domain of this gene was expressed as a fusion protein with glutathione S-transferase in Escherichia coli. Polyclonal antibodies raised against this domain immunoprecipitated the expected 38-kDa P0 protein from the 35S-labeled as well as 32P-labeled P. falciparum cultures. Monospecific human immune sera affinity-purified using the expression clone lambdaPf4 also immunoprecipitated the same size protein from [35S]methionine-labeled P. falciparum protein extract. Purified IgG from polyclonal antibodies raised against the amino-terminal domain of P0 protein completely inhibited the growth of P. falciparum in vitro. This inhibition appears to be mainly at the step of erythrocyte invasion by the parasites.
人类疟原虫恶性疟原虫的一个cDNA表达克隆λPf4，最近被发现是P0核糖体磷蛋白基因的恶性疟原虫同源物，它仅与免疫血清反应，而不与患者血清反应。对P0基因的Northern分析显示存在两种转录本，这两种转录本在寄生虫生命周期的所有不同红细胞内阶段均存在。该基因的一个138个碱基对的氨基末端结构域在大肠杆菌中作为与谷胱甘肽S-转移酶的融合蛋白表达。针对该结构域产生的多克隆抗体从35S标记以及32P标记的恶性疟原虫培养物中免疫沉淀出预期的38 kDa P0蛋白。使用表达克隆λPf4亲和纯化的单特异性人类免疫血清也从[35S]甲硫氨酸标记的恶性疟原虫蛋白提取物中免疫沉淀出相同大小的蛋白。针对P0蛋白氨基末端结构域产生的多克隆抗体纯化的IgG在体外完全抑制了恶性疟原虫的生长。这种抑制似乎主要发生在寄生虫侵入红细胞的步骤。
