Excessive expansions of glutamine (Q)-rich repeats in various human proteins are known to result in severe neurodegenerative disorders such as Huntington's disease and several ataxias. However, the physiological role of these repeats and the consequences of more moderate repeat variation remain unknown. Here, we demonstrate that Q-rich domains are highly enriched in eukaryotic transcription factors where they act as functional modulators. Incremental changes in the number of repeats in the yeast transcriptional regulator Ssn6 (Cyc8) result in systematic, repeat-length-dependent variation in expression of target genes that result in direct phenotypic changes. The function of Ssn6 increases with its repeat number until a certain threshold where further expansion leads to aggregation. Quantitative proteomic analysis reveals that the Ssn6 repeats affect its solubility and interactions with Tup1 and other regulators. Thus, Q-rich repeats are dynamic functional domains that modulate a regulator's innate function, with the inherent risk of pathogenic repeat expansions.
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http://dx.doi.org/10.1016/j.molcel.2015.07.003 | DOI Listing |
Elife
February 2024
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.
Serine(S)/threonine(T)-glutamine(Q) cluster domains (SCDs), polyglutamine (polyQ) tracts and polyglutamine/asparagine (polyQ/N) tracts are Q-rich motifs found in many proteins. SCDs often are intrinsically disordered regions that mediate protein phosphorylation and protein-protein interactions. PolyQ and polyQ/N tracts are structurally flexible sequences that trigger protein aggregation.
View Article and Find Full Text PDFMol Microbiol
May 2022
College of Marine Life Science, Ocean University of China, Qingdao, China.
Kluyveromyces marxianus is the most suitable fungus for inulinase industrial production. However, the underlying transcriptional activation mechanism of the inulinase gene (INU1) is hitherto unclear. Here, we undertook genetic and biochemical analyses to elucidate that a glycolysis regulator KmGcr1p with unique Q-rich repeats is the key transcriptional activator of INU1.
View Article and Find Full Text PDFVirus Evol
January 2022
Rita Levi Montalcini Department of Neuroscience, University of Torino, Corso Raffaello 30, Torino 10125, Italy.
The fusion of the SARS-CoV-2 virus with cells, a key event in the pathogenesis of Covid-19, depends on the assembly of a six-helix fusion core (FC) formed by portions of the spike protein heptad repeats (HRs) 1 and 2. Despite the critical role in regulating infectivity, its distinctive features, origin, and evolution are scarcely understood. Thus, we undertook a structure-guided positional and compositional analysis of the SARS-CoV-2 FC, in comparison with FCs of related viruses, tracing its origin and ongoing evolution.
View Article and Find Full Text PDFProc IEEE Inst Electr Electron Eng
February 2017
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
The presence of abnormally expanded glutamine (Q) repeats within specific proteins ( huntingtin) are the well-established cause of several neurogenerative diseases, including Huntington disease and spinocerebellar ataxias. However, the impact of "expanded Q" stretches on the protein function is not well-understood, mostly due to lack of knowledge about the physiological role of Q repeats and the mechanism by which these repeats achieve functional-specificity. Indeed, is intriguing that regions with such low complexity (low information content) can display exquisite functional specificity.
View Article and Find Full Text PDFBiomed Res Int
March 2017
Department of Biology Education, Kyungpook National University, Daegu 41566, Republic of Korea.
AU-rich element binding/degradation factor 1 (AUF1) plays a role in destabilizing mRNAs by forming complexes with AU-rich elements (ARE) in the 3'-untranslated regions. Multiple AUF1-ARE complexes regulate the translation of encoded products related to the cell cycle, apoptosis, and inflammation. AUF1 contains two tandem RNA recognition motifs (RRM) and a Gln- (Q-) rich domain in their C-terminal region.
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