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Splicing of atypical introns in S. cerevisiae
Cit, Zdeněk ; Půta, František (advisor) ; Pichová, Alena (referee)
Pre-mRNA splicing is a vital process of gene expression important for all eukaryotic organisms. For the proper function of this very complex and dynamic event the presence of few specialized RNA and many proteins that hold a variety of tasks is necessary, not only inside the splicing complex itself, but also beyond this complex. The Prp45 is one of the proteins involved in pre-mRNA splicing in yeast Saccharomyces cerevisiae. Its human homologue, SNW1/SKIP, is involved in splicing but also in other crucial cell processes. The Prp45 protein was reliably reported only to participate in the second transesterification reaction of splicing. But there are also data suggesting its possible involvement in the first transesterification reaction. This work provides further evidences linking protein Prp45 with the first splicing reaction, obtained by the research of cells carrying the mutant allele prp45(1-169). Cells carrying this allele show dropped splicing and accumulation of pre-mRNAs. This thesis therefore also investigated the possible influence of Prp45 protein on the RNA export from the nucleus to the cytoplasm. But no connection between this protein and RNA transport was discovered. Keywords pre-mRNA splicing; Saccharomyces cerevisiae; Prp45; Mer1; Mud2; Prp22; Rrp6; AMA1; SNW1/SKIP
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The role of Prp45p in mRNA expression and maturation
Abrhámová, Kateřina ; Půta, František (advisor) ; Pichová, Alena (referee) ; Janderová, Blanka (referee)
Prp45p of Saccharomyces cerevisiae and Snw1p of Schizosaccharomyces pombe are essential proteins, which share extensive homology with the mammalian transcription regulator and splicing factor SNW/SKIP. We have analyzed the essential function of these proteins in both yeasts and found a mutation (prp45(1-169)) that exhibited temperature sensitivity. The mutant strain harboring the corresponding chromosomal deletion shows temperature sensitive phenotype and hypersensitivity to cycloheximide, hydroxyurea, calcofluor white, and to microtubule inhibitors. At 30řC, the cells are often elongated, deformed, and larger than wt. After synchronization prp45(1-169) cells stop their growth with 2N DNA content at 37řC. We found that the temperature sensitivity is not overcome and the hypersensitivity to microtubule destabilizing drugs is only partially suppressed by the excision of intron from TUB1 gene. This distinguishes prp45(1-169) from those splicing factor's mutants that cause tubulin-dependent G2/M arrest, which can be relieved by the expression of intronless tub1. We performed analysis of splicing in vitro and found that splicing of optimal substrates is not impaired. We also compared the content and stability of RNA in wt-cells and in prp45(1-169) cells at variol temperatures using microarrays. The...
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Interakce xenobiotik s MDR pumpami u S. cerevisiae
Hendrych, T. ; Zlámalová, Marta ; Gášková, Dana ; Pichová, Alena ; Sigler, Karel
The interactions of a number of xenobiotics with two main S. cerevisiae MDR pumps, Pdr5p and Snq2p were studied. The results showed that some compounds do not interact with MDR pumps whereas others affect one or another of the pumps, causing a loss of their ability to transport an indicator substrate out of the cells. This apparent inactivation of the pumps can be due to competition for transport with the indicator substrate or to actual (noncompetitive) inhibition of the pumps
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