Variable repeats in the eukaryotic polyubiquitin gene ubi4 modulate proteostasis and stress survival.
Nat Commun
; 8(1): 397, 2017 08 30.
Article
in En
| MEDLINE
| ID: mdl-28855501
ABSTRACT
Ubiquitin conjugation signals for selective protein degradation by the proteasome. In eukaryotes, ubiquitin is encoded both as a monomeric ubiquitin unit fused to a ribosomal gene and as multiple ubiquitin units in tandem. The polyubiquitin gene is a unique, highly conserved open reading frame composed solely of tandem repeats, yet it is still unclear why cells utilize this unusual gene structure. Using the Saccharomyces cerevisiae UBI4 gene, we show that this multi-unit structure allows cells to rapidly produce large amounts of ubiquitin needed to respond to sudden stress. The number of ubiquitin units encoded by UBI4 influences cellular survival and the rate of ubiquitin-proteasome system (UPS)-mediated proteolysis following heat stress. Interestingly, the optimal number of repeats varies under different types of stress indicating that natural variation in repeat numbers may optimize the chance for survival. Our results demonstrate how a variable polycistronic transcript provides an evolutionary alternative for gene copy number variation.Eukaryotic cells rely on the ubiquitin-proteasome system for selective degradation of proteins, a process vital to organismal fitness. Here the authors show that the number of repeats in the polyubiquitin gene is evolutionarily unstable within and between yeast species, and that this variability may tune the cell's capacity to respond to sudden environmental perturbations.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Saccharomyces cerevisiae
/
Saccharomyces cerevisiae Proteins
/
Polyubiquitin
/
Ubiquitin C
Language:
En
Journal:
Nat Commun
Journal subject:
BIOLOGIA
/
CIENCIA
Year:
2017
Document type:
Article
Affiliation country:
Belgium