Chenik Mehdi, Chaabouni Noura, Ben Achour-Chenik Yosser, Ouakad Meriem, Lakhal-Naouar Inès, Louzir Hechmi, Dellagi Koussay
Laboratoire d'Immunopathologie, Vaccinologie et Génétique Moléculaire, Institut Pasteur de Tunis, 13, Place Pasteur 1002 Tunis-Belvédère, Tunisia.
Biochem Biophys Res Commun. 2006 Mar 10;341(2):541-8. doi: 10.1016/j.bbrc.2006.01.005. Epub 2006 Jan 13.
Here, we describe for the first time a Leishmania specific gene encoding a large 610 amino-acid RAB GTPase (LmLRAB). LmLRAB displays high homologies with the RAB GTPase protein family between amino acids 34 and 284. It contains characteristic signatures of RAB proteins: 4 GTP binding domains, 5 RAB specific domains, 3 RAB subfamily-specific domains, and a prenylation site. lmlrab is a single copy gene, transcribed as a 3.5 kb mRNA, highly conserved in Leishmania species, and encodes a protein doublet of approximately 75 kDa. Immunofluorescence microscopy using LmLRAB-specific antibodies demonstrated that LmLRAB is confined in a structure adjacent to the kinetoplast probably corresponding to an early endosomal/golgi apparatus localization. Interestingly, using quantitative real-time RT-PCR, we showed that the lmlrab gene is up-regulated twice in amastigotes relative to promastigotes. These findings suggest that LmLRAB may play a potential role in Leishmania pathogenicity.
在此，我们首次描述了利什曼原虫中一个编码610个氨基酸的大型RAB GTP酶（LmLRAB）的特异性基因。LmLRAB在氨基酸34至284之间与RAB GTP酶蛋白家族具有高度同源性。它包含RAB蛋白的特征性结构域：4个GTP结合结构域、5个RAB特异性结构域、3个RAB亚家族特异性结构域以及一个异戊二烯化位点。lmlrab是一个单拷贝基因，转录为3.5 kb的mRNA，在利什曼原虫物种中高度保守，并编码一个约75 kDa的蛋白质双峰。使用LmLRAB特异性抗体的免疫荧光显微镜检查表明，LmLRAB局限于与动基体相邻的结构中，可能对应于早期内体/高尔基体定位。有趣的是，通过定量实时RT-PCR，我们发现lmlrab基因在无鞭毛体中相对于前鞭毛体上调了两倍。这些发现表明LmLRAB可能在利什曼原虫的致病性中发挥潜在作用。
