SLIP1, a factor required for activation of histone mRNA translation by the stem-loop binding protein.
Replication-dependent histone mRNAs are the only eukaryotic cellular mRNAs that are not polyadenylated, ending instead in a conserved stem-loop. The 3' end of histone mRNA is required for histone mRNA translation, as is the stem-loop binding protein (SLBP), which binds the 3' end of histone mRNA. We have identified five conserved residues in a 15-amino-acid region in the amino-terminal portion of SLBP, each of which is required for translation. Using a yeast two-hybrid screen, we identified a novel protein, SLBP-interacting protein 1 (SLIP1), that specifically interacts with this region. Mutations in any of the residues required for translation reduces SLIP1 binding to SLBP. The expression of SLIP1 in Xenopus oocytes together with human SLBP stimulates translation of a reporter mRNA ending in the stem-loop but not a reporter with a poly(A) tail. The expression of SLIP1 in HeLa cells also stimulates the expression of a green fluorescent protein reporter mRNA ending in a stem-loop. RNA interference-mediated downregulation of endogenous SLIP1 reduces the rate of translation of endogenous histone mRNA and also reduces cell viability. SLIP1 may function by bridging the 3' end of the histone mRNA with the 5' end of the mRNA, similar to the mechanism of translation of polyadenylated mRNAs.
Cakmakci
Nihal G
NG
Program in Molecular Biology and Biotechnology, CB #7100, University of North Carolina, Chapel Hill, NC 27599, USA.
Lerner
Rachel S
RS
Wagner
Eric J
EJ
Zheng
Lianxing
L
Marzluff
William F
WF
D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000502:physiology*; D002470:Cell Survival; D006367:HeLa Cells; D006657:Histones / Q000235:genetics*; D006801:Humans; D007700:Kinetics; D009687:Nuclear Proteins / Q000378:metabolism*; D009865:Oocytes; D011485:Protein Binding; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics*; D034741:RNA, Small Interfering / Q000494:pharmacology; D016601:RNA-Binding Proteins; D014162:Transfection; D014981:Xenopus; D039221:mRNA Cleavage and Polyadenylation Factors / Q000378:metabolism*
D002352:Carrier Proteins; D006657:Histones; C489104:MIF4GD protein, human; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C092663:SLBP protein, human; D039221:mRNA Cleavage and Polyadenylation Factors