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Functional analysis of the TIF32-HLD-PRT1-RRM-HCR1 module of the yeast translation initiation factor 3
Herrmannová, Anna ; Valášek, Leoš (advisor) ; Mašek, Tomáš (referee)
The eIF3 is in yeast S. cerevisiae composed of five core essential subunits (TIF32, NIP1, PRT1, TIF34 and TIF35) and one nonessential substoichiometric subunit (HCR1), and as such represents the most complex initiation factor among all. Perhaps owing to that, it was shown to stimulate nearly all steps of the initiation pathway culminating in the formation of the 80S initiation complex at the AUG start codon on mRNA. Yeast eIF3 was also demonstrated to assemble together with the ternary complex, eIF1 and eIF5 into so called Multifactor complex that can exist free of ribosomes and whose formation greatly stimulates initiation efficiency. TIF32, the largest eIF3 subunit, was shown to make at least two critical contacts with the 40S ribosomal subunit and its middle domain, designated as the HLD, to share a significant sequence similarity with the HCR1 subunit. Experiments conducted here indicate that the TIF32-HLD and HCR1 share also some functional similarity as the recombinant HLD expressed under control of the HCR1 promoter in a domain- swapping experiment partially suppressed the slow growth phenotype of cells deleted for HCR1. In addition to the HLD, HCR1 also simultaneously interacts with the RRM domain of PRT1, which is considered to be the main scaffolding subunit of eIF3. The group of Dr. P.J....
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The family of 4E translation factors explored in human cell lines
Čečmanová, Vendula ; Mašek, Tomáš (advisor) ; Herrmannová, Anna (referee)
The eIF4E is an important eukaryotic translation initiation factor, because of its ability to bind cap at 5'end of mRNA. There are three members of this protein family found in humans: eIF4E1, eIF4E2 and eIF4E3. eIF4E1 also plays role in in export of some mRNA from nucleus to cytoplasm. This protein is mostly regulated by mTOR signaling pathway and malfunctions in regulation leads to increased cell proliferation and thus tumorogenesis. eIF4E2 plays a role in regulating of translation during embryogenesis and it is known to mediate translation in terms of hypoxia. Role of eIF4E3 is so far shrouded in mystery. Some studies suggest it might be able to suppress tumor growth, but no studies have been done on human eIF4E3. Big potential of our work is, that all proteins we work with, are human. Based on our results, the endogenous amount of eIF4E3 protein is higher than it was thought. This is one of the reasons, why this protein should not escape our attention. In my diploma thesis, I have studied physiological characteristics of cell cultures overexpressing eIF4E proteins after mTOR inhibition treatment. I have realized that the most efficient inhibitor in all tested cell cultures is PP-242, which binds directly into active site of mTOR kinase. I have cloned 3xC FLAG tagged eIF4Es constructs and used...
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Complex structural and functional analysis of individual subunits of yeast translation initiation factor 3.
Herrmannová, Anna
5 ABSTRACT Translation initiation in eukaryotes is a complex process promoted by numerous proteins or protein complexes called eukaryotic initiation factors (eIFs). The eukaryotic initiation factor 3 (eIF3) is a multisubunit complex that has been implicated in several steps of the translation initiation pathway. In yeast Saccharomyces cerevisiae, eIF3 is composed of five essential subunits (a/TIF32, b/PRT1, c/NIP1, g/TIF35, i/TIF34) and one nonessential subunit (j/HCR1). It is our long-term goal to understand how eIF3 promotes different stages of translation initiation and which subunits or their domains play a critical role in this process as well as to map the binding sites of eIF3 on 40S ribosomal subunit and to create a structural model of eIF3 complex. Here I present two structural studies showing interactions between the RNA recognition motif of eIF3b and a short peptide of eIF3j subunits of human eIF3 solved by NMR spectroscopy, and a crystal structure of the C-terminal fragment of yeast b/PRT1 in complex with the full length i/TIF34 subunit at 2.2 Å resolution. In the former study, me and my colleagues showed that the critical determinants mediating this eIF3b-eIF3j interaction are evolutionary conserved, since their mutations in yeast proteins reduced cellular growth rate, eliminated j/HCR1...
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Complex structural and functional analysis of individual subunits of yeast translation initiation factor 3.
Herrmannová, Anna
5 ABSTRACT Translation initiation in eukaryotes is a complex process promoted by numerous proteins or protein complexes called eukaryotic initiation factors (eIFs). The eukaryotic initiation factor 3 (eIF3) is a multisubunit complex that has been implicated in several steps of the translation initiation pathway. In yeast Saccharomyces cerevisiae, eIF3 is composed of five essential subunits (a/TIF32, b/PRT1, c/NIP1, g/TIF35, i/TIF34) and one nonessential subunit (j/HCR1). It is our long-term goal to understand how eIF3 promotes different stages of translation initiation and which subunits or their domains play a critical role in this process as well as to map the binding sites of eIF3 on 40S ribosomal subunit and to create a structural model of eIF3 complex. Here I present two structural studies showing interactions between the RNA recognition motif of eIF3b and a short peptide of eIF3j subunits of human eIF3 solved by NMR spectroscopy, and a crystal structure of the C-terminal fragment of yeast b/PRT1 in complex with the full length i/TIF34 subunit at 2.2 Å resolution. In the former study, me and my colleagues showed that the critical determinants mediating this eIF3b-eIF3j interaction are evolutionary conserved, since their mutations in yeast proteins reduced cellular growth rate, eliminated j/HCR1...
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The family of 4E translation factors explored in human cell lines
Čečmanová, Vendula ; Mašek, Tomáš (advisor) ; Herrmannová, Anna (referee)
The eIF4E is an important eukaryotic translation initiation factor, because of its ability to bind cap at 5'end of mRNA. There are three members of this protein family found in humans: eIF4E1, eIF4E2 and eIF4E3. eIF4E1 also plays role in in export of some mRNA from nucleus to cytoplasm. This protein is mostly regulated by mTOR signaling pathway and malfunctions in regulation leads to increased cell proliferation and thus tumorogenesis. eIF4E2 plays a role in regulating of translation during embryogenesis and it is known to mediate translation in terms of hypoxia. Role of eIF4E3 is so far shrouded in mystery. Some studies suggest it might be able to suppress tumor growth, but no studies have been done on human eIF4E3. Big potential of our work is, that all proteins we work with, are human. Based on our results, the endogenous amount of eIF4E3 protein is higher than it was thought. This is one of the reasons, why this protein should not escape our attention. In my diploma thesis, I have studied physiological characteristics of cell cultures overexpressing eIF4E proteins after mTOR inhibition treatment. I have realized that the most efficient inhibitor in all tested cell cultures is PP-242, which binds directly into active site of mTOR kinase. I have cloned 3xC FLAG tagged eIF4Es constructs and used...
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Complex structural and functional analysis of individual subunits of yeast translation initiation factor 3.
Herrmannová, Anna ; Valášek, Leoš (advisor) ; Krásný, Libor (referee) ; Pospíšek, Martin (referee)
5 ABSTRACT Translation initiation in eukaryotes is a complex process promoted by numerous proteins or protein complexes called eukaryotic initiation factors (eIFs). The eukaryotic initiation factor 3 (eIF3) is a multisubunit complex that has been implicated in several steps of the translation initiation pathway. In yeast Saccharomyces cerevisiae, eIF3 is composed of five essential subunits (a/TIF32, b/PRT1, c/NIP1, g/TIF35, i/TIF34) and one nonessential subunit (j/HCR1). It is our long-term goal to understand how eIF3 promotes different stages of translation initiation and which subunits or their domains play a critical role in this process as well as to map the binding sites of eIF3 on 40S ribosomal subunit and to create a structural model of eIF3 complex. Here I present two structural studies showing interactions between the RNA recognition motif of eIF3b and a short peptide of eIF3j subunits of human eIF3 solved by NMR spectroscopy, and a crystal structure of the C-terminal fragment of yeast b/PRT1 in complex with the full length i/TIF34 subunit at 2.2 Å resolution. In the former study, me and my colleagues showed that the critical determinants mediating this eIF3b-eIF3j interaction are evolutionary conserved, since their mutations in yeast proteins reduced cellular growth rate, eliminated j/HCR1...
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Functional analysis of the TIF32-HLD-PRT1-RRM-HCR1 module of the yeast translation initiation factor 3
Herrmannová, Anna ; Valášek, Leoš (advisor) ; Mašek, Tomáš (referee)
The eIF3 is in yeast S. cerevisiae composed of five core essential subunits (TIF32, NIP1, PRT1, TIF34 and TIF35) and one nonessential substoichiometric subunit (HCR1), and as such represents the most complex initiation factor among all. Perhaps owing to that, it was shown to stimulate nearly all steps of the initiation pathway culminating in the formation of the 80S initiation complex at the AUG start codon on mRNA. Yeast eIF3 was also demonstrated to assemble together with the ternary complex, eIF1 and eIF5 into so called Multifactor complex that can exist free of ribosomes and whose formation greatly stimulates initiation efficiency. TIF32, the largest eIF3 subunit, was shown to make at least two critical contacts with the 40S ribosomal subunit and its middle domain, designated as the HLD, to share a significant sequence similarity with the HCR1 subunit. Experiments conducted here indicate that the TIF32-HLD and HCR1 share also some functional similarity as the recombinant HLD expressed under control of the HCR1 promoter in a domain- swapping experiment partially suppressed the slow growth phenotype of cells deleted for HCR1. In addition to the HLD, HCR1 also simultaneously interacts with the RRM domain of PRT1, which is considered to be the main scaffolding subunit of eIF3. The group of Dr. P.J....
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C-konc. segment NIP1/eIF3c a HCR1 subjednotky eIF3 umožňují jeho vazbu na 40S ribozóm přes RPS33/ASC1 a RPS22
Rutkai, Edit ; Herrmannová, Anna ; Szamecz, Bela ; Valášek, Leoš
One of the rst critical steps of protein synthesis is the recruitment of the eIF2.GTP.Met-tRNAiMet ternary complex (TC) to the 40S ribosome. In yeast, the TC occurs together with eIFs 1, 3 and 5 in a Multifactor complex (MFC) that was shown to function as an important intermediate of the initiation pathway. Our previous study determined several critical domains of the TIF32 and NIP1 subunits of yeast eIF3, the deletion of which, in the background of a wild type gene, signifcantly aected binding of the mutant MFC to the 40S ribosomes. Subsequent identifcation of the two contact points between TIF32 and components of the 40S ribosome enabled us to propose that the major body of the eIF3 complex resides under the head region on the solvent side of the small ribosomal subunit facing down towards its left foot
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