The DEAD box protein Dhh1 stimulates the decapping enzyme Dcp1.
An important control step in the regulation of cytoplasmic mRNA turnover is the removal of the m(7)G cap structure at the 5' end of the message. Here, we describe the functional characterization of Dhh1, a highly conserved member of the family of DEAD box-containing proteins, as a regulator of mRNA decapping in Saccharomyces cerevisiae. Dhh1 is a cytoplasmic protein and is shown to be in a complex with the mRNA degradation factor Pat1/Mtr1 and with the 5'-3' exoribonuclease Xrn1. Dhh1 specifically affects mRNA turnover in the deadenylation-dependent decay pathway, but does not act on the degradation of nonsense-containing mRNAs. Cells that lack dhh1 accumulate degradation intermediates that have lost their poly(A) tail but contain an intact 5' cap structure, suggesting that Dhh1 is required for efficient decapping in vivo. Furthermore, recombinant Dhh1 is able to stimulate the activity of the purified decapping enzyme Dcp1 in an in vitro decapping assay. We propose that the DEAD box protein Dhh1 regulates the access of the decapping enzyme to the m(7)G cap by modulating the structure at the 5' end of mRNAs.
Fischer
Nicole
N
Department of Molecular and Cell Biology, Division of Cell and Developmental Biology, University of California-Berkeley, Berkeley, CA 94720-3200, USA.
Weis
Karsten
K
D000483:Alleles; D003593:Cytoplasm / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D004268:DNA-Binding Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005656:Fungal Proteins / Q000378:metabolism; D017930:Genes, Reporter; D009154:Mutation; D010940:Plant Proteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020365:RNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013997:Time Factors; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C103266:PAT1 protein, S cerevisiae; D010940:Plant Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C418137:Xrn1 protein, plant; D005095:Exoribonucleases; C068398:XRN1 protein, S cerevisiae; D010450:Endopeptidases; C020071:dipeptidyl carboxypeptidase; C445083:DHH1 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases