Ivanova Magdalena I, Thompson Michael J, Eisenberg David
Howard Hughes Medical Institute and University of California--Department of Energy Institute of Genomics and Proteomics, University of California, Los Angeles, CA 90095, USA.
Proc Natl Acad Sci U S A. 2006 Mar 14;103(11):4079-82. doi: 10.1073/pnas.0511298103. Epub 2006 Mar 7.
Identifying sequence determinants of fibril-forming proteins is crucial for understanding the processes causing >20 proteins to form pathological amyloid depositions. Our approach to identifying which sequences form amyloid-like fibrils is to screen the amyloid-forming proteins human insulin and beta(2)-microglobulin for segments that form fibrils. Our screen is of 60 sequentially overlapping peptides, 59 being six residues in length and 1 being five residues, covering every noncysteine-containing segment in these two proteins. Each peptide was characterized as amyloid-like or nonfibril-forming. Amyloid-like peptides formed fibrils visible in electron micrographs or needle-like microcrystals showing a cross-beta diffraction pattern. Eight of the 60 peptides (three from insulin and five from beta(2)-microglobulin) were identified as amyloid-like. The results of the screen were used to assess the computational method, and good agreement between prediction and experiments was found. This agreement suggests that the pair-of-sheets, zipper spine model on which the computational method is based is at least approximately correct for the structure of the fibrils and suggests the nature of the sequence signal for formation of amyloid-like fibrils.
识别形成纤维的蛋白质的序列决定因素对于理解导致20多种蛋白质形成病理性淀粉样沉积的过程至关重要。我们识别哪些序列形成淀粉样纤维的方法是筛选形成纤维的蛋白质——人胰岛素和β2-微球蛋白中的片段。我们的筛选对象是60个连续重叠的肽段，其中59个长度为6个残基，1个长度为5个残基，覆盖这两种蛋白质中每个不含半胱氨酸的片段。每个肽段被鉴定为淀粉样或非纤维形成型。淀粉样肽段形成在电子显微镜下可见的纤维或显示交叉β衍射图案的针状微晶。60个肽段中有8个（3个来自胰岛素，5个来自β2-微球蛋白）被鉴定为淀粉样。筛选结果用于评估计算方法，发现预测与实验结果吻合良好。这种吻合表明计算方法所基于的片层对拉链脊柱模型至少在纤维结构方面大致正确，并表明了形成淀粉样纤维的序列信号的性质。
