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Role of helicases UAP56 and URH49 in viral infection
Nováková, Veronika ; Šroller, Vojtěch (advisor) ; Šmahel, Michal (referee)
Helicases are proteins with the catalytic ability to unwind double-stranded nucleic acids. An important group are helicases with a DEAD motif, which includes helicase UA56 and the more recently discovered helicase URH49. These helicases are orthologs and they share some functions. Both helicases are involved in the splicing of pre-mRNA and they take part in the transport of mRNA from the nucleus to the cytoplasm. Slight differences between the two helicases lead to different affinites for different mRNAs. Overproduction of the URH49 helicase has been reported in many cancer tissues and has therefore been suggested to function as a potential biomarker of adverse cancer prognosis. The association of helicases UAP56 and URH49 with nuclear export has led to research of their role in cells infected by viruses which replicate in the nucleus. The helicases UAP56 and URH49 have been shown to promote virus replication in several ways. They either participate in the transport of viral RNAs into the cytoplasm and thus help to translate important proteins for the virus or play a role in their encapsidation. They also help recruit the export complex, which is normally dependent on the formation of a splicing apparatus, to viral transcripts without introns. The URH49 helicase has also been described to suppress...
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Helicase DHX9 and its role in viral life cycles
Kertisová, Anna ; Horníková, Lenka (advisor) ; Saláková, Martina (referee)
Helicases are proteins that provide strands-unwinding of polystranded conformations of nucleic acids. DHX9 is a representative of helicases with a DExD/H-box motif. It accepts molecules of RNA, DNA and hybrid strucutures as a substrate. Inside the nucleus of the eukaryotic cell, DHX9 participates in the formation of the replication fork or it acts in a complex of trancriptional factors and it connects other proteins with RNA polymerase II. Subsequently DHX9 regulates post-transcritional RNA processing. After a shuttle to the cytoplasm it assists in a correct course of translation of structurated mRNAs. Since DHX9 is involved in nucleic acids-related processes, its role in viral life cycles is investigated. Also it is a part of antiviral signaling pathways of the cell. DHX9 provides an advantage for RNA viruses and retroviruses in their replicative cycle in various manners. The binding of DHX9 on secondary structures of viral RNAs and their eventually remodelation, which causes promotion of viral replication, transcription and translation, is significant. In contrast to that, DNA viruses use DHX9 to regulate host protein expression and minimize its antiviral fuction. Understanding of relationship could lead to more effective aiming of the therapeutic drugs against viral infections. Key words:...
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Analysis of BK virus life cycle
Bakardjieva - Mihaylova, Violeta ; Drda Morávková, Alena (advisor) ; Mindlová, Martina (referee)
Polyomaviruses are small unenvelope DNA viruses, whose replication take place in cell nucleus. Despite its small genome size, these viruses can cause significant changes in the host cell, one of the most significant is cell transformation. Most studies of human pathogens from this family is the focus of clinical research, but do not provide enough information about the individual events of the life cycle of viruses. This thesis mainly aims to determining the exact time when the creation of the individual viral products and generate a timeline of events during natural infection in cells that are targets for BKV in the human body. It was found that the time course of the life cycle of BKV is very similar to those for model polyomaviruses MPyV and SV40 and in permissive cells takes about 40 - 50 hours.
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