Division of Cell and Molecular Biology, Centre for Molecular Microbiology and Infection, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
J Biol Chem. 2011 Mar 18;286(11):9246-56. doi: 10.1074/jbc.M110.130427. Epub 2010 Nov 24.
The 57-residue small hydrophilic endoplasmic reticulum-associated protein (SHERP) shows highly specific, stage-regulated expression in the non-replicative vector-transmitted stages of the kinetoplastid parasite, Leishmania major, the causative agent of human cutaneous leishmaniasis. Previous studies have demonstrated that SHERP localizes as a peripheral membrane protein on the cytosolic face of the endoplasmic reticulum and on outer mitochondrial membranes, whereas its high copy number suggests a critical function in vivo. However, the absence of defined domains or identifiable orthologues, together with lack of a clear phenotype in transgenic parasites lacking SHERP, has limited functional understanding of this protein. Here, we use a combination of biophysical and biochemical methods to demonstrate that SHERP can be induced to adopt a globular fold in the presence of anionic lipids or SDS. Cross-linking and binding studies suggest that SHERP has the potential to form a complex with the vacuolar type H(+)-ATPase. Taken together, these results suggest that SHERP may function in modulating cellular processes related to membrane organization and/or acidification during vector transmission of infective Leishmania.
57 个残基的小亲水性内质网相关蛋白（SHERP）在无复制性载体传播阶段的锥虫寄生虫利什曼原虫中表现出高度特异性、阶段调节表达，该寄生虫是人类皮肤利什曼病的病原体。先前的研究表明，SHERP 作为一种外周膜蛋白定位于内质网的细胞质面和外线粒体膜上，而其高拷贝数表明其在体内具有关键功能。然而，由于缺乏定义的结构域或可识别的同源物，以及缺乏缺乏 SHERP 的转基因寄生虫的明确表型，限制了对这种蛋白质的功能理解。在这里，我们使用生物物理和生化方法的组合来证明，在阴离子脂质或 SDS 的存在下，SHERP 可以被诱导采用球形折叠。交联和结合研究表明，SHERP 有可能与液泡型 H（+）-ATP 酶形成复合物。总之，这些结果表明，SHERP 可能在调节与膜组织和/或酸化相关的细胞过程中发挥作用，这与感染性利什曼原虫的载体传播有关。
