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The yeast non‐Mendelian factor [ ETA + ] is a variant of [ PSI + ], a prion‐like form of release factor eRF3
Author(s) -
Zhou Ping,
Derkatch Irina L.,
Uptain Susan M.,
Patino Maria M.,
Lindquist Susan,
Liebman Susan W.
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.5.1182
Subject(s) - biology , mendelian inheritance , genetics , yeast , saccharomyces cerevisiae , gene
The yeast non‐Mendelian factor [ ETA + ] is lethal in the presence of certain mutations in the SUP35 and SUP45 genes, which code for the translational release factors eRF3 and eRF1, respectively. One such mutation, sup35‐2 , is now shown to contain a UAG stop codon prior to the essential region of the gene. The non‐Mendelian inheritance of [ ETA + ] is reminiscent of the yeast [ PSI + ] element, which is due to a self‐propagating conformation of Sup35p. Here we show that [ ETA + ] and [ PSI + ] share many characteristics. Indeed, like [ PSI + ], the maintenance of [ ETA + ] requires the N‐terminal region of Sup35p and depends on an appropriate level of the chaperone protein Hsp104. Moreover, [ ETA + ] can be induced de novo by excess Sup35p, and [ ETA + ] cells have a weak nonsense suppressor phenotype characteristic of weak [ PSI + ]. We conclude that [ ETA + ] is actually a weak, unstable variant of [ PSI + ]. We find that although some Sup35p aggregates in [ ETA + ] cells, more Sup35p remains soluble in [ ETA + ] cells than in isogenic strong [ PSI + ] cells. Our data suggest that the amount of soluble Sup35p determines the strength of translational nonsense suppression associated with different [ PSI + ] variants.