A single @entity3689 substitution in XXXX eIF-5A results in mRNA stabilization.

@entity43936 @entity1880 @entity70720 @entity10637 @entity25220 @entity563 @entity1521 @entity375 @entity3689 @entity70721
Most factors known to function in mRNA turnover are not essential for cell viability. To identify essential factors, approximately 4000 temperature-sensitive @entity375 strains were screened for an increase in the level of the unstable @entity43936 pre-mRNA. At the non-permissive temperature, five mutants exhibited decreased decay rates of the @entity43936 pre-mRNA and mRNA, and the @entity25220 , @entity70720 and @entity10637 mRNAs. Of these, the mutant ts1159 had the most extensive phenotype. Expression of the @entity70721 gene (encoding eIF-5A) complemented the temperature-sensitive growth and mRNA decay phenotypes of ts1159. The @entity70721 allele was rescued from these cells and shown to encode a @entity563 to @entity1521 change within a predicted alpha-helical segment of the protein. ts1159 also exhibited an approximately 30% decrease in protein synthesis at the restrictive temperature. Measurement of @entity3689 incorporation in wild-type cells incubated with increasing amounts of @entity1880 demonstrated that a decrease in protein synthesis of this magnitude could not account for the full extent of the mRNA decay defects observed in ts1159. Interestingly, the ts1159 cells accumulated uncapped mRNAs at the non-permissive temperature. These results suggest that eIF-5A plays a role in mRNA turnover, perhaps acting downstream of decapping.
