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dc.contributor.advisorBonham-Smith, Peta C.en_US
dc.creatorSavada, Raghavendra Prasaden_US
dc.date.accessioned2011-06-24T18:50:44Zen_US
dc.date.accessioned2013-01-04T04:40:32Z
dc.date.available2012-07-04T08:00:00Zen_US
dc.date.available2013-01-04T04:40:32Z
dc.date.created2011-06en_US
dc.date.issued2011-06en_US
dc.date.submittedJune 2011en_US
dc.identifier.urihttp://hdl.handle.net/10388/etd-06242011-185044en_US
dc.description.abstractRibosomal proteins (RPs), synthesized in the cytoplasm, need to be transported from the cytoplasm to the nucleolus (a nuclear compartment), where a single molecule of each RP assembles with rRNAs to form the large and small ribosomal subunits. The objectives of this research were to identify nuclear/nucleolar localization signals (NLSs/NoLSs; generally basic motifs) that mediate the transport of Arabidopsis RPL23aA, RPL15A and RPS8A into the nucleus and nucleolus, and to study transcriptional regulation and subcellular localization of RPs. While all previous research has shown that nucleolar localization of proteins is mediated by specific basic motifs, in this study, I showed that a specific number of basic motifs mediated nucleolar localization of RPL23aA, rather than any specific motifs. In this protein, single mutations of any of its eight putative NLSs (pNLSs) had no effect on nucleolar localization, however, the simultaneous mutation of all eight completely disrupted nucleolar localization, but had no effect on nuclear localization. Furthermore, mutation of any four of these pNLSs had no effect on localization, while mutation of more than four increasingly disrupted nucleolar localization, suggesting that any combination of four of the eight pNLSs is able to mediate nucleolar localization. These results support a charge-based system for the nucleolar localization of RPL23aA. While none of the eight pNLSs of RPL23aA were required for nuclear localization, in RPS8A and RPL15A, of the 10 pNLSs in each, the N-terminal two and three NLSs, respectively, were absolutely required for nuclear/nucleolar localization. Considering the presence of only a single molecule of each RP in any given ribosome, which obligates the presence of each RP in the nucleolus in equal quantities, I studied transcriptional regulation of Arabidopsis RP genes and the subcellular localization of five RP families to determine the extent of coordinated regulation of these processes. Variation of up to 300-fold was observed in the expression levels of RP genes. However, this variation was drastically reduced when the expression level was considered at the RP gene family level, indicating that coordinate regulation of expression of RP genes, coding for individual RP isoforms, is more stringent at the family level. Subcellular localization also showed differential targeting of RPs to the cytoplasm, nucleus and nucleolus, together with a significant difference in the nucleolar import rates of RPS8A and RPL15A. Although one could expect coordinated regulation of the processes preceding ribosomal subunit assembly in the nucleolus, my results suggest differential regulation of these processes.en_US
dc.language.isoen_USen_US
dc.subjectNuclear/Nucleolar localizationen_US
dc.subjectTranscriptional regulationen_US
dc.subjectArabidopsisen_US
dc.subjectRibosomal proteinsen_US
dc.subjectRibosomesen_US
dc.titleCharacterization of regulation of expression and nuclear/nucleolar localization of Arabidopsis ribsomal proteinsen_US
thesis.degree.departmentBiologyen_US
thesis.degree.disciplineBiologyen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophy (Ph.D.)en_US
dc.type.materialtexten_US
dc.type.genreThesisen_US
dc.contributor.committeeMemberKrone, Patricken_US
dc.contributor.committeeMemberPage, Jonathanen_US
dc.contributor.committeeMemberTodd, Chrisen_US
dc.contributor.committeeMemberWilson, Kenen_US
dc.contributor.committeeMemberHepworth, Shelleyen_US


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