1P-1155 (2010/12/07)
ポスター会場2 神戸国際展示場1号館2階 
Poster Room 2 Kobe Int'l Exhibition Hall 1, 2F

スプライソソーム・タンパク質の進化：高保存・低変更なシステム、ただし寄生性ゲノムにおける劇的な変更
Evolution of spliceosomal proteins: High conservation and low modification, but drastic change in parasitic genome
^○嶋田 誠¹，内山 郁夫²，前田 明^1
1藤田保衛大・総医研・遺伝子発現，²基生研・ゲノム情報

Pre-mRNA splicing in eukaryotes takes place precisely in sophisticated complexes (spliceosomes) consisting of five U snRNAs and over 200 proteins. Most of these splicing factors emerged already in an early common eukaryotic ancestor, however, little is known about their origin and the diversity because they have been studied using the limited number of model organisms. To understand the evolution of pre-mRNA splicing mechanisms in eukaryotes, we systematically analyzed orthologous relationships among spliceosomal proteins in 25 species of eukaryotic genomes. We used the computational tool termed 'Research Environment for Comparative Genomics (RECOG)' that can rapidly create comprehensive ortholog groups using hierarchical clustering algorithm for 'all-against-all' pairwise peptide sequence alignments. We searched for the orthologs of 100 and 176 human proteins that consist of the complexes A and B, respectively. From these human proteins, we obtained orthologs of 176 protein domain groups. The number of domains detected in the genomes of organisms examined was varied from 11 in nucleomorph of Guillardia theta to 164 domains in fly (D. melanogaster). Among these detected domains, only distinctive 4 domains are shared in 3 metazoan species (human, fly and nematode). Only 8 domains were uniquely found in human. These data suggest that the protein components of spliceosomes are seldom modified along human lineage. We only detected small number of orthologs of human spliceosomal proteins in parasitic and symbiotic organisms, irrespective of lineage or intron size, which will afford a clue to understand evolution of transportation system in symbiotic genome.