The transcription factor associated Ccr4 and Caf1 proteins are components of the major cytoplasmic mRNA deadenylase in Saccharomyces cerevisiae.
The major pathways of mRNA turnover in eukaryotes initiate with shortening of the poly(A) tail. We demonstrate by several criteria that CCR4 and CAF1 encode critical components of the major cytoplasmic deadenylase in yeast. First, both Ccr4p and Caf1p are required for normal mRNA deadenylation in vivo. Second, both proteins localize to the cytoplasm. Third, purification of Caf1p copurifies with a Ccr4p-dependent poly(A)-specific exonuclease activity. We also provide evidence that the Pan2p/Pan3p nuclease complex encodes the predominant alternative deadenylase. These results, and previous work on Pan2p/Pan3p, define the mRNA deadenylases in yeast. The strong conservation of Ccr4p, Caf1p, Pan2p, and Pan3p indicates that they will function as deadenylases in other eukaryotes. Interestingly, because Ccr4p and Caf1p interact with transcription factors, these results suggest an unexpected link between mRNA synthesis and turnover.
Department of Molecular and Cellular Biology and, Howard Hughes Medical Institute, University of Arizona, Tucson, AZ 85721, USA.
M
M
Tucker
M A
MA
Valencia-Sanchez
R R
RR
Staples
J
J
Chen
C L
CL
Denis
R
R
Parker
D015152:Blotting, Northern; D003593:Cytoplasm / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D005095:Exoribonucleases / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005656:Fungal Proteins / Q000378:metabolism* / Q000502:physiology; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D012260:Ribonucleases; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism* / Q000502:physiology
D005095:Exoribonucleases; D005656:Fungal Proteins; D012333:RNA, Messenger; D012260:Ribonucleases; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C078657:CCR4 protein, S cerevisiae; C101747:PAN3 protein, S cerevisiae; C079009:POP2 protein, S cerevisiae