Laha Bhakti, Verma Amit Kumar, Biswas Bapi, Sengodan Satheesh Kumar, Rastogi Akanksha, Willard Belinda, Ghosh Monidipa
Department of Biotechnology, National Institute of Technology Durgapur, Mahatma Gandhi Avenue, Durgapur, West Bengal, 713209, India.
Mass Spectrometry Laboratory for Protein Sequencing, Cleveland Clinic - Lerner Research Institute, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.
Parasitol Res. 2019 May;118(5):1609-1623. doi: 10.1007/s00436-019-06286-x. Epub 2019 Mar 22.
The protozoan parasite, Leishmania donovani, undergoes several molecular adaptations and secretes many effector molecules for host cell manipulation and successful parasitism. The current study identifies an albumin-like secretory protein, expressed in its extracellular promastigote forms. A leishmanial complementary DNA sequence of a partial gene has been cloned, and the encoded peptide (14 kD) is used for the production of polyclonal antibody. This targeted antibody identifies a large native protein (66.421 kD), expressed stage-specifically in promastigotes. Through electron microscopic studies, the native protein is found to be localized in the flagellar pocket and flagella and at the surface of the promastigotes. This native protein is purified with the same customized antibody for future characterization and sequencing. The sequence analysis reveals its homology with the mammalian serum albumin. It is evidenced from in silico studies that this albumin-like protein remains associated with long-chain fatty acids while in vitro studies indicate its close association with membrane cholesterol. Since antibody-mediated blocking compromises the parasite infectivity, these leishmanial albumin-like molecules are hereby proposed to play an instrumental role in the infectivity of L. donovani to peripheral blood monocyte cells. Thus, identification and characterization of an albumin-like protein in L. donovani promastigotes may be interpreted as a molecular adaptation candidate. It may be hypothesized that the parasite mimics the mammalian system for importing fatty acids into the intracellular amastigotes, facilitating its host cell infectivity.
原生动物寄生虫杜氏利什曼原虫会经历多种分子适应性变化，并分泌许多效应分子来操纵宿主细胞并成功寄生。当前的研究鉴定出一种在其细胞外前鞭毛体形式中表达的类白蛋白分泌蛋白。已克隆了部分基因的利什曼原虫互补DNA序列，并使用编码的肽（14 kD）来制备多克隆抗体。这种靶向抗体识别出一种大型天然蛋白（66.421 kD），该蛋白在前鞭毛体中阶段特异性表达。通过电子显微镜研究发现，该天然蛋白定位于鞭毛袋、鞭毛以及前鞭毛体表面。用相同的定制抗体纯化该天然蛋白，以备将来进行表征和测序。序列分析揭示了它与哺乳动物血清白蛋白的同源性。计算机模拟研究表明，这种类白蛋白在体外与长链脂肪酸相关，而体外研究表明它与膜胆固醇密切相关。由于抗体介导的阻断会损害寄生虫的感染性，因此这些利什曼原虫类白蛋白分子在杜氏利什曼原虫对外周血单核细胞的感染性中起着重要作用。因此，杜氏利什曼原虫前鞭毛体中类白蛋白的鉴定和表征可被视为一种分子适应性候选物。可以推测，该寄生虫模仿哺乳动物系统将脂肪酸导入细胞内无鞭毛体，从而促进其对宿主细胞的感染。
