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Delivery of genomes of nonenveloped DNA viruses into the cell nucleus
Bílková, Eva ; Forstová, Jitka (advisor) ; Hatáková, Ladislava (referee)
The majority of DNA viruses have to deliver their genome to the cell nucleus, which provi- des factors required for their replication and transcription. This work is focused on this proces of small nonenveloped DNA viruses. It describes delivery of the adenovirus, parvovirus, pa- pillomavirus and polyomavirus genomes into the cell nucleus. These viruses are endocyted by the cell and travel to the enveloped compartments. Viral particle undergoes changes afffected by surrounding environment and activity of cellular enzymes, which results in its escape from enveloped vesicle mediated by the viral proteins. Some viruses use direct interactions with cytos- keletal transport components for travelling to the cell nucleus. In most cases, viral DNA enters cell nucleus via nuclear pore complex, although the evidence of alternative mechanisms exists as well. This work focuses on early phases of the life cycle of the selected viruses and the nucleus targeting of their genomes. Understanding the mechanisms of viral DNA nuclear import may contribute to discovery of new anti-viral therapies.
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Role of phosphorylation in nuclear import of viral proteins and complexes
Pokorná, Karolína ; Forstová, Jitka (advisor) ; Roučová, Kristina (referee)
Replication of many different viruses occurs in the nucleus of the host cell. These viruses discovered ways how to overcome the nuclear membrane and often use cell transport machinery to transport their proteins and genome into the nucleus. For many viral proteins the timing of their nuclear import in order to secure correct viral replication is important. Regulated nuclear import also allows these proteins to perform several functions depending on their localization. Nuclear import of viral proteins and complexes can be regulated by phosphorylation. Phosphorylation can, for example, modulate affinity of proteins for importins or other cellular proteins. Phosphorylation can also cause conformational change, which can lead to unmasking of localization sequence.
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Characterisation of the mechanisms regulating 53BP1 nuclear transport
Liďák, Tomáš ; Macůrek, Libor (advisor) ; Brábek, Jan (referee)
Tumor suppressor p53-binding protein 1 (53BP1) is an integral part of a sophisticated network of cellular pathways termed as the DNA damage response (DDR). These pathways are specialized in the maintenance of genome integrity. Recently, it was reported that nuclear import of 53BP1 depends on importin ß. Here, I used fluorescence microscopy and co-immunoprecipitation experiments to identify its nuclear localization signal (NLS). Clusters of basic amino acids 1667-KRK-1669 and 1681-KRGRK- 1685 were required for 53BP1 interaction with importin ß and for its nuclear localization. Short peptide containing these two clusters was sufficient for interaction with importin ß and targeting EGFP to the nucleus. Additionally, the effect of 53BP1 phosphorylation at S1678 on its nuclear import was examined. Mimicking the phosphorylation in the 53BP1-S1678D mutant decreased the binding to importin ß and resulted in a mild defect in 53BP1 nuclear import. However, 53BP1 entered the nucleus continuously during the cell cycle, suggesting that CDK-dependent phosphorylation of S1678 probably does not significantly contribute to the regulation of 53BP1 nuclear transport. Taken together, 53BP1 NLS meets the attributes of a classical bipartite NLS. Although no cell cycle-dependent regulation of its import was observed, the...
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Role of phosphorylation in nuclear import of viral proteins and complexes
Pokorná, Karolína ; Forstová, Jitka (advisor) ; Roučová, Kristina (referee)
Replication of many different viruses occurs in the nucleus of the host cell. These viruses discovered ways how to overcome the nuclear membrane and often use cell transport machinery to transport their proteins and genome into the nucleus. For many viral proteins the timing of their nuclear import in order to secure correct viral replication is important. Regulated nuclear import also allows these proteins to perform several functions depending on their localization. Nuclear import of viral proteins and complexes can be regulated by phosphorylation. Phosphorylation can, for example, modulate affinity of proteins for importins or other cellular proteins. Phosphorylation can also cause conformational change, which can lead to unmasking of localization sequence.
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Delivery of genomes of nonenveloped DNA viruses into the cell nucleus
Bílková, Eva ; Forstová, Jitka (advisor) ; Hatáková, Ladislava (referee)
The majority of DNA viruses have to deliver their genome to the cell nucleus, which provi- des factors required for their replication and transcription. This work is focused on this proces of small nonenveloped DNA viruses. It describes delivery of the adenovirus, parvovirus, pa- pillomavirus and polyomavirus genomes into the cell nucleus. These viruses are endocyted by the cell and travel to the enveloped compartments. Viral particle undergoes changes afffected by surrounding environment and activity of cellular enzymes, which results in its escape from enveloped vesicle mediated by the viral proteins. Some viruses use direct interactions with cytos- keletal transport components for travelling to the cell nucleus. In most cases, viral DNA enters cell nucleus via nuclear pore complex, although the evidence of alternative mechanisms exists as well. This work focuses on early phases of the life cycle of the selected viruses and the nucleus targeting of their genomes. Understanding the mechanisms of viral DNA nuclear import may contribute to discovery of new anti-viral therapies.
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