Ccr4p is the catalytic subunit of a Ccr4p/Pop2p/Notp mRNA deadenylase complex in Saccharomyces cerevisiae.
The major pathways of mRNA turnover in eukaryotic cells are initiated by shortening of the poly(A) tail. Recent work has identified Ccr4p and Pop2p as components of the major cytoplasmic deadenylase in yeast. We now demonstrate that CCR4 encodes the catalytic subunit of the deadenylase and that Pop2p is dispensable for catalysis. In addition, we demonstrate that at least some of the Ccr4p/Pop2p-associated Not proteins are cytoplasmic, and lesions in some of the NOT genes can lead to defects in mRNA deadenylation rates. The Ccr4p deadenylase is inhibited in vitro by addition of the poly(A) binding protein (Pab1p), suggesting that dissociation of Pab1p from the poly(A) tail may be rate limiting for deadenylation in vivo. In addition, the rapid deadenylation of the COX17 mRNA, which is controlled by a member of the Pumilio family of deadenylation activators Puf3p, requires an active Ccr4p/Pop2p/Not deadenylase. These results define the Ccr4p/Pop2p/Not complex as the cytoplasmic deadenylase in yeast and identify positive and negative regulators of this enzyme complex.
Tucker
Morgan
M
Department of Molecular and Cellular Biology and Howard Hughes Medical Institute, 1007 East Lowell Street, University of Arizona, Tucson, AZ 85721, USA.
Staples
Robin R
RR
Valencia-Sanchez
Marco A
MA
Muhlrad
Denise
D
Parker
Roy
R
D001665:Binding Sites; D020134:Catalytic Domain; D027682:Cation Transport Proteins / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D000079922:Copper Transport Proteins; D003593:Cytoplasm / Q000378:metabolism; D005095:Exoribonucleases / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D018832:Molecular Chaperones; D039102:Poly(A)-Binding Proteins; D017434:Protein Structure, Tertiary; D012331:RNA, Fungal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
C089931:CDC36 protein, S cerevisiae; C079592:CDC39 protein, S cerevisiae; C100359:COX17 protein, S cerevisiae; D027682:Cation Transport Proteins; D018797:Cell Cycle Proteins; D000079922:Copper Transport Proteins; D005656:Fungal Proteins; D018832:Molecular Chaperones; D039102:Poly(A)-Binding Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C078657:CCR4 protein, S cerevisiae; D005095:Exoribonucleases; D012260:Ribonucleases; C079009:POP2 protein, S cerevisiae