Analysis of RPS15aE, an Isoform of a Plant-Specific Evolutionarily Distinct Ribosomal Protein in Arabidopsis thaliana, Reveals its Potential Role as a Growth Regulator
- 108 Downloads
There is increasing evidence for ribosome heterogeneity in biological systems. In Arabidopsis thaliana, the ribosomal protein S15a is encoded by six separate genes, which fall into two evolutionarily distinct categories (Type I and Type II). Type I S15a is a universally conserved component of cytosolic ribosomes, whereas there is ambiguity as to the specific subcellular location of Type II S15a (cytosolic and/or mitochondrial ribosomes). In this study, we investigated the functional significance of the distinct form of ribosomal protein S15a (Type II) in Arabidopsis by examining: the evolutionary relationship of eukaryotic S15a proteins with respect to organellar homologs, the expression of individual Type II S15a genes during various developmental stages by RT-PCR, and the phenotypes of an insertional mutation into the RPS15aE gene. The Type II S15a proteins are plant specific, and the duplication event that gave rise to the Type II S15a genes appears to have occurred during the evolution of land plants. The genes encoding Type II S15a in Arabidopsis are differentially expressed, and mutant plants in which the gene encoding S15aE is knocked down produce larger leaves, longer roots, and possess larger cells than wild-type plants suggesting that the RPS15aE isoform of Type II S15a may act as a regulator of translational activity. Our results add significantly to the understanding of the protein constitution of plant ribosomes and the functional significance of ribosome heterogeneity.
KeywordsArabidopsis Ribosome Ribosomal protein Protein synthesis Translational regulation
This work was supported, in part, by an intramural University Research Council grant awarded to Kathleen Szick-Miranda. Stacey Abidayo and Ammar S. Zanial were supported by the Student Research Scholars Program at CSUB and by the MARC U*STAR training program, award number T34GM069349, from the National Institute of General Medical Sciences. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of General Medical Sciences or the National Institutes of Health. Ali S. Zanial was supported by the Student Research Scholars Program at CSUB. In addition, we are grateful to Brandon Pratt for statistical assistance and helpful discussions, Julia Bailey-Serres for critical review of this manuscript, Elizabeth Waters and Virginia Vandergon for their comments and discussion on the phylogenetic analyses, and Rick Miranda for experimental design.
- Cammarano P, Pons S, Romeo A, Galdieri M, Gualerzi C (1972) Characterization of unfolded and compact ribosomal subunits from plants and their relationship to those of lower and higher animals: evidence for physicochemical heterogeneity among eucaryotic ribosomes. Biochim Biophys Acta 281(4):571–596PubMedGoogle Scholar
- Heazlewood J, Tonti-Filippini J, Gout A, Day D, Whelan J, Millar AH (2004) Experimental analysis of the Arabidopsis mitochondrial proteome highlights signaling and regulator components, provides assessment of targeting prediction programs and indicates plant-specific mitochondrial proteins. Plant Cell 16:241–256CrossRefPubMedGoogle Scholar
- Hruz T, Laule O, Szabo G, Wessendorp F, Bleuler S, Oertle L, Widmayer P, GruissemW, Zimmermann P (2008) Genevestigator V3: a reference expression database for the meta-analysis of transcriptomes. Advances in Bioinformatics 2008, Article ID 420747. doi: 10.1155/2008/420747
- Matheson AT, Auer J, Ramierez C, Bock A (1990) Structure and evolution of archaebacterial ribosomal proteins. In: Hill WE, Dahlberg A, Garrett RE, Moore PB, Schlessinger D, Warner DC (eds) The ribosome: structure, function and evolution. American Society of Microbiologists, Wasington, D.C, pp 617–633Google Scholar
- Merrick WC, Hershey JWB (1996) The pathway and mechanism of eukaryotic protein synthesis. In: Hershey JWB, Mathews MB, Sonenberg N (eds) Translational control. Cold Spring Harbor Laboratory, Cold Spring Harbor, pp 31–69Google Scholar
- Nicolaï M, Roncato MA, Canoy AS, Rouquie D, Sarda X, Freyssinet G, Robaglia C (2006) Large-scale analysis of mRNA translation states during sucrose starvation in Arabidopsis cells identifies cell proliferation and chromatin structure as targets of translational control. Plant Physiol 141(2):663–673CrossRefPubMedGoogle Scholar
- Odintsova TI, Muller EC, Ivanov AV, Egorov TA, Bienert R, Vladimirov SN, Kostka S, Otto A, Wittmann-Liebold B, Karapova GG (2003) Characterization and analysis of posttranslational modifications of the human large cytoplasmic ribosomal subunit proteins by mass spectrometry and Edman sequencing. J Protein Chem 22:249–258CrossRefPubMedGoogle Scholar
- Tishchenko SV, Vassilieva JM, Platonova OB, Serganov AA, Fomenkova NP, Mudrik ES, Piendl W, Ehresmann C, Ehresmann B, Garber MB (2001) Isolation, crystallization, and investigation of ribosomal protein S8 complexed with specific fragments of rRNA of bacterial or archaeal origin. Biochemistry (Moscow) 66(9):948–953CrossRefGoogle Scholar
- Wittmann-Leibold B, Kopke AKE, Arndt E, Kromer W, Hatakeyama T, Wittmann H-G (1990) Sequence comparison and evolution of ribosomal proteins and their genes. In: Hill WE, Dahlberg A, Garrett RE, Moore PB, Schlessinger D, Warner DC (eds) The ribosome: structure, function and evolution. American Society of Microbiologists, Washington, D.C., pp 598–616Google Scholar