Variable Glutamine-Rich Repeats Modulate Transcription Factor Activity.

Mol Cell

Laboratory of Systems Biology, VIB, Gaston Geenslaan 1, 3001 Heverlee, Belgium; Laboratory of Genetics and Genomics, Centre of Microbial and Plant Genetics (CMPG), Department M2S, KU Leuven, Gaston Geenslaan 1, 3001 Heverlee, Belgium. Electronic address:

Published: August 2015

AI Article Synopsis

  • Excessive glutamine-rich repeats in certain human proteins are linked to serious neurodegenerative diseases, yet the impact of moderate repeat variations is still unclear.* -
  • The study shows that Q-rich domains are abundant in eukaryotic transcription factors, affecting gene expression and leading to observable phenotypic changes, particularly in the yeast regulator Ssn6.* -
  • As the number of repeats in Ssn6 increases, its function enhances up to a point; beyond a certain length, further repeats can cause aggregation, highlighting the balancing act between functional modulation and potential pathogenic expansion.*

Article Abstract

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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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4543046PMC
http://dx.doi.org/10.1016/j.molcel.2015.07.003DOI Listing

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