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Nucleic Acids Res. 2013 Sep;41(16):7960-71. doi: 10.1093/nar/gkt558. Epub 2013 Jun 26.

Structural and biochemical studies of SLIP1-SLBP identify DBP5 and eIF3g as SLIP1-binding proteins.

Author information

1
Structural Cell Biology Department, Max Planck Institute of Biochemistry, Munich, D-82152 Germany and Program in Molecular Biology and Biotechnology, University of North Carolina, Chapel Hill, NC 27599, USA.

Abstract

In metazoans, replication-dependent histone mRNAs end in a stem-loop structure instead of the poly(A) tail characteristic of all other mature mRNAs. This specialized 3' end is bound by stem-loop binding protein (SLBP), a protein that participates in the nuclear export and translation of histone mRNAs. The translational activity of SLBP is mediated by interaction with SLIP1, a middle domain of initiation factor 4G (MIF4G)-like protein that connects to translation initiation. We determined the 2.5 Å resolution crystal structure of zebrafish SLIP1 bound to the translation-activation domain of SLBP and identified the determinants of the recognition. We discovered a SLIP1-binding motif (SBM) in two additional proteins: the translation initiation factor eIF3g and the mRNA-export factor DBP5. We confirmed the binding of SLIP1 to DBP5 and eIF3g by pull-down assays and determined the 3.25 Å resolution structure of SLIP1 bound to the DBP5 SBM. The SBM-binding and homodimerization residues of SLIP1 are conserved in the MIF4G domain of CBP80/20-dependent translation initiation factor (CTIF). The results suggest how the SLIP1 homodimer or a SLIP1-CTIF heterodimer can function as platforms to bridge SLBP with SBM-containing proteins involved in different steps of mRNA metabolism.

PMID:
23804756
PMCID:
PMC3763545
DOI:
10.1093/nar/gkt558
[Indexed for MEDLINE]
Free PMC Article

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