Institute of Biochemistry, Christian-Albrechts-University Kiel, Olshausenstr. 40, 24098 Kiel, Germany.
Dev Comp Immunol. 2010 Mar;34(3):323-30. doi: 10.1016/j.dci.2009.11.003. Epub 2009 Nov 26.
The caenopore-5 protein encoded by the spp-5 gene is one of the 33 caenopores identified in Caenorhabditis elegans and is a pore-forming peptide which plays an important role in the elimination of Escherichia coli ingested by the worm. Thus, caenopore-5 appears to contribute to the nutrition of the worm while simultaneously protecting the organism against pathogens. Here, three-dimensional heteronuclear NMR spectroscopy was used to solve the solution structure of caenopore-5. The NMR data revealed that two conformers of caenopore-5 exist in solution which differ by the isomerization of the peptide bond of Pro-81. The overall structure of the two caenopore-5 conformers consists of five amphiphatic helices connected by three disulfide bonds. The five helices are arranged in a folded leaf which is the characteristic signature of the SAPLIP family. The structure presented here is the first of an effector protein of the defensive system elucidated for the well-known model organism C. elegans.
由 spp-5 基因编码的 caenopore-5 蛋白是在秀丽隐杆线虫中鉴定出的 33 种 caenopores 之一，是一种形成孔的肽，在消除线虫摄入的大肠杆菌中发挥重要作用。因此，caenopore-5 似乎有助于线虫的营养，同时保护生物体免受病原体的侵害。在这里，使用三维异核 NMR 光谱法解决了 caenopore-5 的溶液结构。NMR 数据表明，caenopore-5 在溶液中存在两种构象，它们通过 Pro-81 的肽键异构化而有所不同。两种 caenopore-5 构象的整体结构由五个通过三个二硫键连接的两亲性螺旋组成。这五个螺旋排列成一个折叠的叶子，这是 SAPLIP 家族的特征标志。这里呈现的结构是为著名的模式生物秀丽隐杆线虫阐明的防御系统的效应蛋白的第一个结构。
