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Biophysical Characterization of Coronaviral nsp14 Inhibition
Trembulaková, Pavla ; Bouřa, Evžen (advisor) ; Dejmek, Milan (referee)
RNA virus SARS-CoV-2 caused worldwide pandemic of severe disease COVID-19 which lasted more than a year. Repair mechanisms of this virus during replication process significantly reduce efficiency of nucleotide analog drugs, eg. remdesivir. Nonstructural protein (nsp) 14 and nsp10 form a complex which acts as an exonuclease enzyme and will be furthrer referred to as an ExoN complex. This complex can probably cause lower efficiency of incorporation of nucleotide analogs compared to viruses without exonuclease enzymes. The two-protein complex with active site on nsp14 containing two magensium ions seems like a good target for testing potent inhobitors. Among possible inhibitors of SARS-CoV-2 exonuclease complex are isobavachalcone and sofalcone. According to published studies, those small organic molecules chelate magensium ions in active site of exonulease part in nsp14. This results in inactivation of ExoN complex active site in nsp14 structure and disables the catalytic function which acts as repairing element in RNA synthesis process. This tesis focuses on characterization of inhibition of protein complex nsp14 and nsp10 in presence of small selected molecules, isobavachalcone and sofalcone. Exonuclease activity assays in presence of various RNA substrates were performed. Furthermore, there have been...
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Methyltransferases of human +ssRNA viruses
Skořepa, Jan ; Bouřa, Evžen (advisor) ; Otava, Tomáš (referee)
The aim of this bachelor's thesis is a structural and functional description of viral methyltransferases of important human +ssRNA viruses from the families Coronaviridae and Flaviviridae. Over 400 million people are infected with diseases such as Dengue, Yellow fever, or Japanese encephalitis (Flaviviridae) every year. During the current pandemic of the SARS-CoV-2 virus (Coronaviridae), more than 750 million people have already been infected worldwide. Methyltransferases are involced in the synthesiz of the cap structure at the 5' end of the viral RNA, which increases its stability and facilitates translation. A detailed structural understanding of proteins NS5 (Flaviviridae methyltransferase), nsp14 and nsp16 (Coronaviridae methyltransferases) is necessary for the subsequent development of their inhibitors. As antivirals, these could help with the treatment of viral diseases caused by coronaviruses and flaviviruses.
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Design and evaluation of potential viral methyltransferase inhibitors
Kocek, Hugo ; Nencka, Radim (advisor) ; Grantz Šašková, Klára (referee)
A global pandemic of SARS-CoV-2 confirmed the pandemic potential of the Coronaviridae family and pointed out the need for novel antiviral drugs. The SARS-CoV-2 pandemic has been tamed thanks to mRNA vaccines; however, monoclonal antibodies and small molecules such as nirmatrelvir (protease inhibitor), remdesivir (polymerase inhibitor), or molnupiravir (mutagen) are currently also available. It is worth noting that remdesivir and molnupiravir were previously investigated as antivirals against different pathogens. SARS-CoV-2 encodes 16 non-structural proteins, and two of them - methyltransferases (MTases) nsp14 and nsp16 - participate in RNA capping as the virus must mimic the host's mRNA to evade the cellular antiviral sensors (e.g., IFIT1) and replicate. These MTases are structurally very similar to those of SARS-Co-V; therefore, we might expect that inhibitors of SARS-CoV-2 MTases could be used in the future against different coronaviruses. For the reasons mentioned above, this thesis focuses on developing novel MTase inhibitors targeting SARS-CoV-2 nsp14 and nsp16. The design was based on S-adenosyl-L-homocysteine (SAH; endogenous inhibitor of MTases) and an in silico compound library was constructed with various replacements for SAH's amino acid moiety. The potential inhibitory activity was...
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Structural and functional characterization of inhibition of a coronaviral methyltransferase.
Ivanovská, Dana ; Bouřa, Evžen (advisor) ; Faltová, Lenka (referee)
Coronaviral methyltransferases participate in the modification of the 5'-end of viral RNA. Their enzymatic activity not only ensures efficient mRNA translation, but also allows the virus to escape the recognition of the innate immune system. This work is focused on the SARS-CoV- 2 methyltransferases (the methyltransferase domain of the nonstructural protein 14, MT14, the nonstructural protein 16 and its cofactor - the nonstructural protein 10, nsp16/10), which represent attractive molecular targets for therapeutic intervention. The aim of this work was to structurally characterize the coronaviral methyltransferases in complex with various small molecules. The recombinantly prepared proteins were purified and subsequently subjected to crystallization trials. The obtained crystals of the nsp16/10 heterodimer in complex with sinefungin were soaked in a solution containing a S-adenosyl-L-homocysteine analogue. Crystals suitable for X-ray crystallography of MT14 in complex with two different inhibitors were obtained by optimizing the identified primary crystallization conditions. The aquired structural data of the MT14 inhibitory complexes will serve as a basis for the design of new small molecule inhibitors targeting the S-adenosyl-L-methionine binding site. Keywords: methyltransferase, nsp14, nsp16,...
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SARS-CoV-2 methyltransferases as druggable targets
Kocek, Hugo ; Nencka, Radim (advisor) ; Bouřa, Evžen (referee)
Novel coronavirus (earlier referred to as "nCoV2019") became part of our lives in March 2020 and overnight turned everything upside-down. This virus is transmitted via respiratory droplets and causes respiratory diseases COVID-19 which can be severe and even fatal. So far, no effective treatment has been discovered and vaccination is our biggest hope thanks to its high efficacy. It is important to point out, that new mutations may possess problems and escape immunity induced by the vaccination. During the whole pandemic, many approved drugs were tested against SARS-CoV-2 (for example favipiravir, toremifene, and hydroxychloroquine) but none of those drugs showed to be effective against SARS-CoV-2 in clinical trials. The only approved antiviral drug is nucleotide analog remdesivir which showed significant efficacy against SARS-CoV-2 in clinical trials. However, timing and overall patient's health condition play a key role. Development of new antiviral drugs is necessary given the fact that this is the third time we face coronavirus with the potential to cause pandemic since the beginning of the 21st century. Therefore, it is likely that another new coronavirus will emerge. This thesis focuses on S-adenosylmethionine-dependent methyltransferases nsp14 and nsp16 from SARS-CoV-2 because they play a key...
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