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dc.contributor.advisorWang, Hongen_US
dc.contributor.advisorXiao, Weien_US
dc.creatorQian, Shifengen_US
dc.date.accessioned2013-09-16T19:52:00Z
dc.date.available2013-09-16T19:52:00Z
dc.date.created2012-02en_US
dc.date.issued2013-07-29en_US
dc.date.submittedFebruary 2012en_US
dc.identifier.urihttp://hdl.handle.net/10388/ETD-2012-02-364en_US
dc.description.abstractIn eukaryotic organisms, polyubiquitination is the modification of a protein with polymerized ubiquitin (Ub) chain. This process is well known for its function in targeting proteins for degradation by the 26S proteasome. However, a polyUb chain assembled through the lysine 63 residue of the Ub moiety (Lys63-linked polyubiquitination) has been shown to play a signaling role rather than targeting proteins for degradation. In plants, the functions of Lys63-linked polyubiquitination are currently not well understood. Ub-protein ligase (E3) catalyzes the last step in the ubiquitination reactions, and to a large extent it also determines the substrate specificity of protein ubiquitination. In order to study the roles of Lys63-linked polyubiquitination in plants, two E3s of Arabidopsis thaliana, proteins encoded by AtCHIP and At1g74370 (tentatively named E3-A1), were chosen for functional studies, since they interacted with AtUbc13A protein. Sequence analysis showed that AtCHIP is the only member in the family. A T-DNA insertion mutant line (Atchip-1) was obtained to study the AtCHIP gene knock-out effect. The mutant line was grown in normal conditions and further tested in a variety of conditions: hormonal treatments, osmotic stress, seed deterioration, high temperature stress, high-intensity light stress, oxidative stress and DNA damaging stress. However, no clear difference was observed between the mutant and wild type plants based on the several parameters measured. Sequence analysis of E3-A1 indicated two closely related proteins, tentatively named E3-A2 and E3-A3. As E3-A1 and E3-A2 appeared to share more sequence similarity, RNA interference (RNAi) transformants, with the level of transcripts for either of the two E3-A genes reduced by over 90% were generated. Selected RNAi mutant lines for E3-A1 and E3-A2 were crossed with each other, and double RNAi mutants were obtained. However, no distinct phenotype was detected under normal, high-sucrose or hormonal conditions for either single or double RNAi lines. Although various assays did not reveal a significant phenotype in the mutants in this study, the materials generated and the assays used will benefit a wider range of phenotypic survey in the future.en_US
dc.language.isoengen_US
dc.subjectUbiquitinen_US
dc.subjectligaseen_US
dc.subjectUbc13en_US
dc.subjectlysine 63en_US
dc.subjectArabidopsis thalianaen_US
dc.subjectAtCHIPen_US
dc.titleIdentification and Functional Studies of Arabidopsis thaliana Ubc13-interacting E3 Ubiquitin Ligasesen_US
thesis.degree.departmentBiochemistryen_US
thesis.degree.disciplineBiochemistryen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Science (M.Sc.)en_US
dc.type.materialtexten_US
dc.type.genreThesisen_US
dc.contributor.committeeMemberMoore, Stanley A.en_US
dc.contributor.committeeMemberLoewen, Michele C.en_US
dc.contributor.committeeMemberRoesler, William J.en_US


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