| dc.contributor.author | Archibald, John M. | en_US |
| dc.date.accessioned | 2014-10-21T12:36:17Z | |
| dc.date.available | 2001 | |
| dc.date.issued | 2001 | en_US |
| dc.identifier.other | AAINQ66656 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55785 | |
| dc.description | Chaperone-assisted protein folding is a universal cellular process. The chaperonins are a class of evolutionarily related molecular chaperones that form multisubunit double-ring complexes and facilitate protein folding through the hydrolysis of ATP. This thesis examines (primarily) the role of gene duplication in the origin and evolution of chaperonins in Archaea and the eukaryotic cytosol. | en_US |
| dc.description | The polymerase chain reaction (PCR) was used to isolate chaperonin genes from thermophilic archaea. Phylogenetic analyses of archaeal chaperonins reveal a complex pattern of gene duplication, gene conversion and gene loss, and suggest that hetero-oligomeric chaperonin complexes have evolved multiple times independently during the history of this group. A novel chaperonin subunit-encoding gene was also isolated from two species of Sulfolobus. | en_US |
| dc.description | Eukaryotic cytosolic chaperonin genes were isolated from two putative early-diverging amitochondriate protists, Trichomonas vaginalis and Giardia lamblia. In contrast to the lineage-specific pattern of gene duplication observed in archaea, numerous duplications took place early in eukaryotic evolution and produced eight distinct chaperonin paralogs, prior to the diversification of all eukaryotes under investigation. Further studies revealed significant differences in the rates of amino acid sequence evolution of eukaryotic chaperonins compared to those in Archaea, and among the different eukaryotic chaperonins themselves. | en_US |
| dc.description | Molecular evolutionary studies were also performed on chaperones encoded in the 'nucleomorph' genome of the cryptomonad alga, Guillardia theta. The G. theta nucleomorph---the remnant nucleus of a photosynthetic eukaryotic endosymbiont---was found to retain genes encoding cytosolic forms of HSP70, HSP90 and eight cytosolic chaperonin subunits. Striking differences in the degree of conservation of the various nucleomorph-encoded molecular chaperones were observed, suggesting reduced (or different) evolutionary constraints on the functions of the chaperones in this unusual cellular context. | en_US |
| dc.description | Finally, the taxonomic sampling of eukaryotic cytosolic chaperonin genes was expanded to include the 'jakobid' flagellates, an enigmatic group of free-living, mitochondriate protists. Unlike most protein-coding genes in protists, the chaperonin genes of two jakobids, Reclinomonas americana and Malawimonas jakobiformis, were found to possess numerous spliceosomal introns. An analysis of the intron positions in these genes from a wide diversity of eukaryotes suggests that many of the intron-sparse or intron-lacking protist lineages have lost spliceosomal introns during their evolutionary history. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 2001. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Genetics. | en_US |
| dc.subject | Biology, Microbiology. | en_US |
| dc.subject | Chemistry, Biochemistry. | en_US |
| dc.title | Studies on the evolution of archaeal and eukaryotic chaperonins. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
