IDENTIFICATION OF FOSSIL SEQUENCES COMPARING SEQUENCES FROM DISTANT ORGANISMS

化石序列的鉴定与遥远生物体的序列比较

• 批准号: 3845103
• 负责人: J M CLAVERIE
• 金额: --
• 依托单位: NATIONAL LIBRARY OF MEDICINE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3845103
• 关键词: Invertebrata; bacteria; biochemical evolution; eukaryote; evolution; information systems; protein sequence

Sequence alignments of homologue proteins from evolutionary distant organisms are used to pinpoint regions of structural and functional importance. Over long periods only the most constrained segments retain a detectable similarity with each others. This concept was extended to the whole database, by performing cross-comparisons of comprehensive sets of sequences from various kingdoms and phyla with evolutionary distances ranging from 2 billion years for the eukaryote/eubacteria divergence to 550 million years for the coelomate radiation. Significant similarities between these sets thus correspond to strongly conserved ancestral features. Using a series of matching/orthogonalization procedures, 500 independent ancestral types were detected within contemporary sequences. This fossil set only represents 4% of the original database but significantly matches 40% of the whole. Thus, it realizes a 10-fold enrichment in sequences of the greatest structural/ functional significance and is an optimal source for the definition of motifs. Approximately 200 of those highly conserved sequences correspond to proteins the role of which is not obviously central, and warrant further analysis. Theoretical computations suggest that the 500 ancestral types defined so far constitute most of the fossil sequences detectable in modern sequences. This is consistent with another independent study comparing 3 large new datasets: partial cDNAs from human and nematode and ORFs from chromosome III of yeast. Thus, known proteins might already include representative for most ancestral features antedating the coelomate radiation.

进化距离的同源蛋白的序列比对 生物体被用来精确定位结构和功能区域 重要性。在较长的时间内，只有最受限制的线段才会保留 彼此之间有明显的相似之处。这一概念被扩展到 整个数据库，通过执行全面的 来自不同王国和门类的进化距离的序列 从真核生物/真细菌分化的20亿年到 体腔动物辐射的年龄为5.5亿年。显著相似之处 因此在这些集合之间对应着高度保守的祖先 功能。使用一系列匹配/正交化过程，500 在同时代的序列中发现了独立的祖先类型。 这个化石集只占原始数据库的4%，但 与整体的40%显著匹配。因此，它实现了10倍的 最大结构/功能序列的富集化 它具有重要的意义，是定义主题的最佳来源。 这些高度保守的序列中大约有200个对应于 蛋白质的作用不是很明显的中心，并需要进一步 分析。理论计算表明，500种祖先类型 到目前为止已定义的化石序列构成了在 现代的序列。这与另一项独立研究一致。 比较3个大型新数据集：来自人类和线虫的部分cDNA和 酵母三号染色体上的ORFs。因此，已知的蛋白质可能已经 包括大多数祖先特征的代表性 体腔辐射。