Comparative Study Of The Structure Of Ribosomal Protein Genes From 3 Different Model Systems: Implication On The Mechanism Of Coordinate Expression Of Ribosomal Protein Genes

Ribosome is one of the most abundantorganelles in all living cells and plays acrucial role for cell growth. Synthesis of ribosomal components is tightly linked tochanges of growth condition because in actively growing cells, a huge amount ofenergy is devoted to the synthesis of this protein synthesizing machinery. We havecomparatively analyzed the structure of ribosomal protein (RP) genes among S.cerevisiae, human and A. thaliana. In both S. cerevisiae and A. thaliana, there arefew putative transcriptional factor binding motifs present in the proximal promoterregion with a highly positional bias in most of the ribosomal protein genes. Incontrast, no general transcriptional factor binding motif can be found in the promoterregions of human RP genes. On the other hand, there is an over-representeddistribution of oligo-pyrimidine tract near the transcriptional start site in almost allhuman RP genes when compared to the other two organisms. This element istherefore a likely candidate involved in the coordinated regulation of human RPgenes. We also noticed that the distance between ATG start codon and the nearestexon-intron junction is very short in most RP genes when compared to all othergenes in the genomes in all three organisms. In addition, the sequencessurrounding the ATG start codon and the 5' and 3' splice sites of the intron nearest tothe ATG-containing exon show distinct and high degree of conservation whencompared to the similar regions in all other genes in the genomes in all three modelsystems. These findings hint the possible clues which may eventually lead to therecognition of the mechanism underlying the coordinated regulation of ribosomalprotein genes in eukaryotes.