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Title: An analysis of Lsm protein complexes
Author: Reijns, Martin
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2006
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Recombinant yeast Lsm proteins were purified from Escherichia coli and tested for their ability to promote annealing of the U4 and U6 snRNAs and to unwind a DNA/RNA duplex resembling the 3’ stem-loop of U6 snRNA. For comparison, Hfq, the Sm-like protein from E. coli, and recombinant human Lsm complexes were used in the same in vitro assays. The results are consistent with their ability to promote RNA/RNA annealing and to modulate RNA secondary structure, which, in vivo, may also allow them to affect RNA/protein interactions. The function of LSM4 was studied by overexpression and depletion of wild-type Lsm4p, and by expression of an Lsm4p C-terminal deletion mutant. Results suggest that Lsm4p affects cell morphology and that its C-terminus promotes efficient recruitment of Lsm1-7p to P-bodies and may promote P-body formation. LSM5 was shown to be dispensable for cell visibility, and its depletion was shown to affect levels of U4, U6 and U4/U6 RNAs similar to effects in Ism6Δ and Ism7Δ strains. The involvement of the different domains of Lsm1p and Lsm8p in localisation of these proteins to the cytoplasm (to P-bodies under stress conditions) and nucleus respectively was investigated by creating (deletion) mutants and hybrids of various domains of these proteins. Results suggest that the N-termini of both proteins play a central role in targeting them to their respective cellular locations. The in vitro studies reveal that the RNA chaperone function of Sm-like proteins appears to have been conserved from bacteria to eukaryotes. Presumably, gene duplication and formation of hetereo-multimeric complexes in higher organisms has allowed functional diversification.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available