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BMC Molecular Biology (1)
PLoS ONE (1)
Alexandrov, Alexander I. (1)
Glebov, Oleg O (1)
Kochneva-Pervukhova, Natalia V (1)
Kochneva-Pervukhova, Natalia V. (1)
Packeiser, Anna N (1)
Smirnov, Vladimir N (1)
Ter-Avanesyan, Michael D (1)
Ter-Avanesyan, Michael D. (1)
Tuite, Mick F. (1)
Urakov, Valery N (1)
Valouev, Igor A (1)
Vishnevsky, Alexander Yu (1)
Year of Publication
Amyloid-Mediated Sequestration of Essential Proteins Contributes to Mutant Huntingtin Toxicity in Yeast
Alexandrov, Alexander I.
Ter-Avanesyan, Michael D.
Tuite, Mick F.
Polyglutamine expansion is responsible for several neurodegenerative disorders, among which Huntington disease is the most well-known. Studies in the yeast model demonstrated that both aggregation and toxicity of a huntingtin (htt) protein with an expanded polyglutamine region strictly depend on the presence of the prion form of Rnq1 protein ([PIN+]), which has a glutamine/asparagine-rich domain.
Here, we showed that aggregation and toxicity of mutant htt depended on [PIN+] only quantitatively: the presence of [PIN+] elevated the toxicity and the levels of htt detergent-insoluble polymers. In cells lacking [PIN+], toxicity of mutant htt was due to the polymerization and inactivation of the essential glutamine/asparagine-rich Sup35 protein and related inactivation of another essential protein, Sup45, most probably via its sequestration into Sup35 aggregates. However, inhibition of growth of [PIN+] cells depended on Sup35/Sup45 depletion only partially, suggesting that there are other sources of mutant htt toxicity in yeast.
The obtained data suggest that induced polymerization of essential glutamine/asparagine-rich proteins and related sequestration of other proteins which interact with these polymers represent an essential source of htt toxicity.
N-terminal region of Saccharomyces cerevisiae eRF3 is essential for the functioning of the eRF1/eRF3 complex beyond translation termination
Urakov, Valery N
Valouev, Igor A
Packeiser, Anna N
Vishnevsky, Alexander Yu
Glebov, Oleg O
Smirnov, Vladimir N
Ter-Avanesyan, Michael D
BMC Molecular Biology
Termination of translation in eukaryotes requires two release factors, eRF1, which recognizes all three nonsense codons and facilitates release of the nascent polypeptide chain, and eRF3 stimulating translation termination in a GTP-depended manner. eRF3 from different organisms possess a highly conservative C region (eRF3C), which is responsible for the function in translation termination, and almost always contain the N-terminal extension, which is inessential and vary both in structure and length. In the yeast Saccharomyces cerevisiae the N-terminal region of eRF3 is responsible for conversion of this protein into the aggregated and functionally inactive prion form.
Here, we examined functional importance of the N-terminal region of a non-prion form of yeast eRF3. The screen for mutations which are lethal in combination with the SUP35-C allele encoding eRF3C revealed the sup45 mutations which alter the N-terminal domain of eRF1 and increase nonsense codon readthrough. However, further analysis showed that synthetic lethality was not caused by the increased levels of nonsense codon readthrough. Dominant mutations in SUP35-C were obtained and characterized, which remove its synthetic lethality with the identified sup45 mutations, thus indicating that synthetic lethality was not due to a disruption of interaction with proteins that bind to this eRF3 region.
These and other data demonstrate that the N-terminal region of eRF3 is involved both in modulation of the efficiency of translation termination and functioning of the eRF1/eRF3 complex outside of translation termination.
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