P0143Ribosomal Assembly Genes in Arabidopsis thaliana
Ribosomes are the biological nano-machines responsible for translation of mRNAs into proteins. Assembly of ribosomes is thought to be evolutionarily conserved amongst eukaryotes. While much of our current knowledge on ribosome assembly comes from studies in Saccharomyces cerevisiae, there is little information on the process in plants.
Of the ~120 genes involved in ribosomal assembly in yeast, most are present in multiple copies in the Arabidopsis genome, e.g., S. cerevisiae NOG1 protein sequence shows 63, 59 and 48% similarity to Arabidopsis thaliana AtNOG1-1 (AT1G50920), AtNOG1-2 (AT1G10300) and AtNOG1-3 (AT1G80770), respectively; ScPRP43 has 77% similarity with both AtPRP43-1 (AT3G62310) and AtPRP43-2 (AT2G47250); ScNOC2 has 47 and 45% similarity to AtNOC1-1 (AT2G18220) and AtNOC1-2 (AT3G55510), respectively; and ScHAS1 is 71 and 72% similar to AtHAS1-1 (AT3G18600) and AtHAS1-2 (AT5G65900). ScNOP7 has one ortholog in Arabidopsis AtNOP7 (AT5G14520) that is 55% similar to ScNOP7. Each A. thaliana gene family is differentially expressed at different stages of the Arabidopsis life cycle; AtNOP7 is expressed highest at the bolting stage, while AtNOG1-1 is expressed the highest at senescence. AtNOP7-GFP and AtNOG1-1-GFP both localise to the nucleus. Initial screening of SALK T-DNA insertion lines for AtNOP7 and AtNOG1-1 do not present any observable mutant phenotype, however, future over-expression and pyramiding of all copies of each gene family along with yeast-2-hybridization study, will help to identify individual gene and family gene functions in plant ribosome assembly.