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Catalytic function of DNA-dependent RNA polymerases
Sýkora, Michal ; Vopálenský, Václav (advisor) ; Lichá, Irena (referee)
DNA-dependent RNA polymerase is a highly organised protein complex that is responsible for gene expression and its regulation. Multisubunit RNA polymerase with its several catalytic activities is responsible for transcription of genes to RNA copies in all cellular organisms. During transcription RNA polymerase undergoes substantial conformational changes depending on the conditions in a particular cell. RNA polymerase in a state designated as an elongation complex passes through repetitive cycles of adding a nucleotide to the growing RNA chain. The active center contains two magnesium ions which coordinate the reactive groups of substrates. Furthermore, the active center contains structural elements that participate in binding of substrate, propper orientation of substrate towards the template strand and translocation of the RNA polymerase. The most important of these mobile structural elements are the bridge helix and the trigger loop whose conformational changes accompanies nucleotide addition cycle. Advances in the structural and biochemical characterization of RNA polymerase open new possibilities in the understanding of the transcription mechanism, its fidelity and control.
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Intrinsic transcription termination by multisubunit RNA polymerases
Vojáčková, Jitka ; Sýkora, Michal (advisor) ; Kuthan, Martin (referee)
Transcription is a process of genetic information rewriting from DNA sequence to RNA copy by DNA dependent RNA polymerase. Two mechanisms of transcription termination are known for bacteria: intrinsic transcription termination, independent of any accessory factors, and transcription termination dependent on proten factor called Rho. Intrinsic transcription termination is common mainly for bacteria, yet different, but partially similar forms of intrinsic transcription termination occur also in eukaryotes and archaea. This thesis includes a brief summary of RNA polymerase structure and elongation complex stability, describes individual steps of intrinsic transcription termination mechanism in bacteria including all disscused models and gives examples of intrinsic transcription termination in eukaryotes and archaea and their comparison with bacterial model of intrinsic transcription termination. Key words: RNA polymerase, elongation complex, intrinsic transcription termination, hairpin RNA structures
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Catalytic function of DNA-dependent RNA polymerases
Sýkora, Michal ; Vopálenský, Václav (advisor) ; Lichá, Irena (referee)
DNA-dependent RNA polymerase is a highly organised protein complex that is responsible for gene expression and its regulation. Multisubunit RNA polymerase with its several catalytic activities is responsible for transcription of genes to RNA copies in all cellular organisms. During transcription RNA polymerase undergoes substantial conformational changes depending on the conditions in a particular cell. RNA polymerase in a state designated as an elongation complex passes through repetitive cycles of adding a nucleotide to the growing RNA chain. The active center contains two magnesium ions which coordinate the reactive groups of substrates. Furthermore, the active center contains structural elements that participate in binding of substrate, propper orientation of substrate towards the template strand and translocation of the RNA polymerase. The most important of these mobile structural elements are the bridge helix and the trigger loop whose conformational changes accompanies nucleotide addition cycle. Advances in the structural and biochemical characterization of RNA polymerase open new possibilities in the understanding of the transcription mechanism, its fidelity and control.
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