Xu Yanji, Takvorian Peter, Cali Ann, Wang Fang, Zhang Hong, Orr George, Weiss Louis M
Albert Einstein College of Medicine, 1300 Morris Park Avenue, Room 504 Forchheimer Building, Bronx, NY 10461, USA.
Infect Immun. 2006 Jan;74(1):239-47. doi: 10.1128/IAI.74.1.239-247.2006.
Microsporidia form environmentally resistant spores that are critical for their host-to-host transmission and persistence in the environment. The spore walls of these organisms are composed of two layers, the exospore and the endospore. Two spore wall proteins (SWP1 and SWP2) have been previously identified in members of the Encephalitozoonidae family. These proteins localize to the exospore. The endospore is known to contain chitin, and a putative glycosylphosphatidylinositol (GPI)-anchored chitin deacetylase has been localized to the plasmalemma-endospore interface. Using proteomic techniques, we have identified a new spore wall protein (SWP3) that is located in the endospore. The gene for this protein is located on chromosome 1 and corresponds to the open reading frame ECU01_1270. SWP3 is predicted to have a signal peptide and to be GPI anchored. Consistent with these modifications, two-dimensional electrophoresis demonstrated that SWP3 has an acidic pI and a molecular mass of <20 kDa. By immunoelectron microscopy, this protein was found on the cell surface during sporogony and in the endospore in mature spores. SWP3 has several potential O-glycosylation sites, and it is possible that it is a mannosylated protein like the major polar tube protein (PTP1).
微孢子虫形成具有环境抗性的孢子，这些孢子对于它们在宿主间传播以及在环境中持续存在至关重要。这些生物体的孢子壁由两层组成，即外孢子和内孢子。先前已在脑炎微孢子虫科成员中鉴定出两种孢子壁蛋白（SWP1和SWP2）。这些蛋白定位于外孢子。已知内孢子含有几丁质，并且一种推定的糖基磷脂酰肌醇（GPI）锚定的几丁质脱乙酰酶已定位于质膜 - 内孢子界面。利用蛋白质组学技术，我们鉴定出一种位于内孢子中的新孢子壁蛋白（SWP3）。该蛋白的基因位于1号染色体上，对应于开放阅读框ECU01_1270。预测SWP3具有信号肽且为GPI锚定。与这些修饰一致，二维电泳表明SWP3具有酸性pI且分子量小于20 kDa。通过免疫电子显微镜观察，该蛋白在孢子形成过程中出现在细胞表面，在成熟孢子的内孢子中也有发现。SWP3有几个潜在的O - 糖基化位点，并且它有可能像主要极管蛋白（PTP1）一样是一种甘露糖基化蛋白。
