A 3' exonuclease that specifically interacts with the 3' end of histone mRNA.
Metazoan histone mRNAs end in a highly conserved stem-loop structure followed by ACCCA. Previous studies have suggested that the stem-loop binding protein (SLBP) is the only protein binding this region. Using RNA affinity purification, we identified a second protein, designated 3'hExo, that contains a SAP and a 3' exonuclease domain ... and binds the same sequence. Strikingly, 3'hExo can bind the stem-loop region both separately and simultaneously with SLBP. Binding of 3'hExo requires the terminal ACCCA, whereas binding of SLBP requires the 5' side of the stem-loop region. Recombinant 3'hExo degrades RNA substrates in a 3'-5' direction and has the highest activity toward the wild-type histone mRNA. Binding of SLBP to the stem-loop at the 3' end of RNA prevents its degradation by 3'hExo. These features make 3'hExo a primary candidate for the exonuclease that initiates rapid decay of histone mRNA upon completion and/or inhibition of DNA replication.
Mesh Terms:
Amino Acid Sequence, Animals, Baculoviridae, Cloning, Molecular, DNA, Exonucleases, Hela Cells, Histones, Humans, Mass Spectrometry, Models, Genetic, Molecular Sequence Data, Nuclear Proteins, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, RNA, RNA, Messenger, RNA-Binding Proteins, Rabbits, Time Factors, Two-Hybrid System Techniques, mRNA Cleavage and Polyadenylation Factors
Amino Acid Sequence, Animals, Baculoviridae, Cloning, Molecular, DNA, Exonucleases, Hela Cells, Histones, Humans, Mass Spectrometry, Models, Genetic, Molecular Sequence Data, Nuclear Proteins, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, RNA, RNA, Messenger, RNA-Binding Proteins, Rabbits, Time Factors, Two-Hybrid System Techniques, mRNA Cleavage and Polyadenylation Factors
Mol. Cell
Date: Aug. 01, 2003
PubMed ID: 14536070
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