Mutations in VPS16 and MRT1 stabilize mRNAs by activating an inhibitor of the decapping enzyme.
Decapping is a rate-limiting step in the decay of many yeast mRNAs; the activity of the decapping enzyme therefore plays a significant role in determining RNA stability. Using an in vitro decapping assay, we have identified a factor, Vps16p, that regulates the activity of the yeast decapping enzyme, Dcp1p. Mutations in the VPS16 gene result in a reduction of decapping activity in vitro and in the stabilization of both wild-type and nonsense-codon-containing mRNAs in vivo. The mrt1-3 allele, previously shown to affect the turnover of wild-type mRNAs, results in a similar in vitro phenotype. Extracts from both vps16 and mrt1 mutant strains inhibit the activity of purified Flag-Dcp1p. We have identified a 70-kDa protein which copurifies with Flag-Dcp1p as the abundant Hsp70 family member Ssa1p/2p. Intriguingly, the interaction with Ssa1p/2p is enhanced in strains with mutations in vps16 or mrt1. We propose that Hsp70s may be involved in the regulation of mRNA decapping.
Zhang
S
S
Department of Molecular Genetics, Robert Wood Johnson Medical School, New Jersey, USA.
Williams
C J
CJ
Hagan
K
K
Peltz
S W
SW
D000251:Adenosine Triphosphatases; D018389:Codon, Nonsense; D004722:Endoribonucleases / Q000037:antagonists & inhibitors*; D005656:Fungal Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D008565:Membrane Proteins; D009154:Mutation; D011485:Protein Binding; D039381:RNA Cap-Binding Proteins; D012315:RNA Caps / Q000378:metabolism*; D020871:RNA Stability; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D012641:Selection, Genetic; D033921:Vesicular Transport Proteins
D018389:Codon, Nonsense; D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D039381:RNA Cap-Binding Proteins; D012315:RNA Caps; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C080045:VPS16 protein, S cerevisiae; D033921:Vesicular Transport Proteins; C100868:DCP1 protein, S cerevisiae; D004722:Endoribonucleases; D000251:Adenosine Triphosphatases; C095973:SSA1 protein, S cerevisiae