Molecular dissection of mRNA poly(A) tail length control in yeast.
In eukaryotic cells, newly synthesized mRNAs acquire a poly(A) tail that plays several fundamental roles in export, translation and mRNA decay. In mammals, PABPN1 controls the processivity of polyadenylation and the length of poly(A) tails during de novo synthesis. This regulation is less well-detailed in yeast. We have recently demonstrated that Nab2p is necessary and sufficient for the regulation of polyadenylation and that the Pab1p/PAN complex may act at a later stage in mRNA metabolism. Here, we show that the presence of both Pab1p and Nab2p in reconstituted pre-mRNA 3'-end processing reactions has no stimulating nor inhibitory effect on poly(A) tail regulation. Importantly, the poly(A)-binding proteins are essential to protect the mature mRNA from being subjected to a second round of processing. We have determined which domains of Nab2p are important to control polyadenylation and found that the RGG-box work in conjunction with the two last essential CCCH-type zinc finger domains. Finally, we have tried to delineate the mechanism by which Nab2p performs its regulation function during polyadenylation: it likely forms a complex with poly(A) tails different from a simple linear deposit of proteins as it has been observed with Pab1p.
Viphakone
Nicolas
N
Université Victor Segalen Bordeaux 2, CNRS, Institut de Biochimie et Génétique Cellulaires, Bordeaux, France.
Voisinet-Hakil
Florence
F
Minvielle-Sebastia
Lionel
L
D020413:3' Untranslated Regions / Q000737:chemistry; D045304:Cytochromes c / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D011061:Poly A / Q000378:metabolism; D039102:Poly(A)-Binding Proteins / Q000378:metabolism*; D026723:Polyadenylation; D011062:Polynucleotide Adenylyltransferase / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012331:RNA, Fungal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers
D020413:3' Untranslated Regions; C014059:CYC1 protein, S cerevisiae; C080773:NAB2 protein, S cerevisiae; D029543:Nucleocytoplasmic Transport Proteins; D039102:Poly(A)-Binding Proteins; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C450100:pab1 protein, S cerevisiae; D011061:Poly A; D045304:Cytochromes c; D011062:Polynucleotide Adenylyltransferase