The Rpb7p subunit of yeast RNA polymerase II plays roles in the two major cytoplasmic mRNA decay mechanisms.
The steady-state level of mRNAs is determined by the balance between their synthesis by RNA polymerase II (Pol II) and their decay. In the cytoplasm, mRNAs are degraded by two major pathways; one requires decapping and 5' to 3' exonuclease activity and the other involves 3' to 5' degradation. Rpb7p is a Pol II subunit that shuttles between the nucleus and the cytoplasm. Here, we show that Rpb7p is involved in the two mRNA decay pathways and possibly couples them. Rpb7p stimulates the deadenylation stage required for execution of both pathways. Additionally, Rpb7p is both an active component of the P bodies, where decapping and 5' to 3' degradation occur, and is capable of affecting the P bodies function. Moreover, Rpb7p interacts with the decapping regulator Pat1p in a manner important for the mRNA decay machinery. Rpb7p is also involved in the second pathway, as it stimulates 3' to 5' degradation. Our genetic analyses suggest that Rpb7p plays two distinct roles in mRNA decay, which can both be uncoupled from Rpb7p's role in transcription. Thus, Rpb7p plays pivotal roles in determining mRNA levels.
Lotan
Rona
R
Department of Molecular Microbiology, Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa 31096, Israel.
Goler-Baron
Vicky
V
Duek
Lea
L
Haimovich
Gal
G
Choder
Mordechai
M
D003593:Cytoplasm / Q000378:metabolism*; D022083:Cytoplasmic Structures / Q000378:metabolism; D005800:Genes, Fungal; D049452:Green Fluorescent Proteins / Q000378:metabolism; D046912:Multiprotein Complexes / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D026723:Polyadenylation; D011485:Protein Binding; D021122:Protein Subunits / Q000378:metabolism*; D021381:Protein Transport; D012319:RNA Polymerase II / Q000378:metabolism*; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013696:Temperature; D020798:Two-Hybrid System Techniques
D046912:Multiprotein Complexes; D021122:Protein Subunits; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D012319:RNA Polymerase II; C470553:RPB7 protein, S cerevisiae