Amino acid transport in schistosomes - Characterization of the permease heavy chain SPRM1hc
Amino acid transport in schistosomes - Characterization of the permease heavy chain SPRM1hc
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DOI：
10.1074/jbc.m703512200
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发表时间：
2007-07-27
影响因子：
4.8
通讯作者：
Skelly, Patrick J.
中科院分区：
文献类型：
--
作者：
Krautz-Peterson, Greice;Camargo, Simone;Skelly, Patrick J.
血吸虫是人类寄生的扁虫，构成了全球重要的公共卫生问题。成体寄生虫生活在血液中，它们通过体表(被层)输入氨基酸等营养物质。一个氨基酸转运体，血吸虫渗透酶1轻链，SPRM1lc，属于糖蛋白相关转运体家族(GpaAT)的成员，已在血吸虫中被鉴定。在对曼氏血吸虫和日本血吸虫基因组进行广泛搜索后，只发现了与gpaATs相关的SLC3糖蛋白家族中的一个成员。在这份报告中，我们对这个血吸虫通透性重链(SPRM1hc)基因和蛋白进行了鉴定。据预测，72 kDa的基因产物具有单一的跨膜结构域、(βα)(8)(Tim Barrel)构象和催化三联体。非洲爪哇卵母细胞用SPRM1lc功能性表达SPRM1hc，可导入苯丙氨酸、精氨酸、赖氨酸、丙氨酸、谷氨酰胺、组氨酸、色氨酸和亮氨酸。生化特性表明，在非洲爪哇提取物和血吸虫提取物中，SPRM1hc与SPRM1lc形成高分子量的复合体，该复合体被还原剂破坏。实时定量聚合酶链式反应和Western分析表明，SPRM1hc在所研究的血吸虫各个生命阶段(虫卵、尾蚴、血吸虫幼虫、成年雄性和雌性)中都有表达。免疫定位结果表明，SPRM1hc广泛分布于成虫、雄虫和雌虫。与SPRM1hc功能促进从宿主血液中吸收养分的假设一致，免疫金电子显微镜证实该蛋白分布在与宿主相互作用的被膜上。我们认为，表面暴露的、宿主相互作用的、营养运输蛋白，如SPRM1异二聚体，是有希望的候选疫苗。
Schistosomes are human parasitic flatworms that constitute an important public health problem globally. Adult parasites live in the bloodstream where they import nutrients such as amino acids across their body surface (the tegument). One amino acid transporter, Schistosome Permease 1 light chain, SPRM1lc, a member of the glycoprotein-associated family of transporters (gpaAT), has been characterized in schistosomes. Only a single member of the SLC3 family of glycoproteins that associate with gpaATs is found following extensive searching of the genomes of Schistosoma mansoni and S. japonicum. In this report, we characterize this schistosome permease heavy chain (SPRM1hc) gene and protein. The 72-kDa gene product is predicted to possess a single transmembrane domain, a (beta alpha)(8) (TIM barrel) conformation and a catalytic triad. Xenopus oocytes functionally expressing SPRM1hc with SPRM1lc import phenylalanine, arginine, lysine, alanine, glutamine, histidine, tryptophan, and leucine. Biochemical characterization demonstrates that in Xenopus extracts and in schistosome extracts SPRM1hc is associated into a high molecular weight complex with SPRM1lc that is disrupted by reducing agents. Quantitative real-time PCR and Western analysis demonstrate that SPRM1hc is expressed in each schistosome life stage examined (eggs, cercariae, schistosomula, adult males and females). SPRM1hc is widely distributed throughout adult male and female worms as determined by immunolocalization. Consistent with the hypothesis that SPRM1hc functions to facilitate nutrient uptake from host blood, immunogold electron microscopy confirms that the protein is distributed on the host-interactive tegumental membranes. We propose that surface-exposed, host-interactive, nutrient-transporting proteins like the SPRM1 heterodimer are promising vaccine candidates.