von Moeller, H., Lerner, R., Ricciardi, A., Basquin, C., Marzluff, W.F., and Conti, E. (2013) Structural and biochemical studies of SLIP1-SLBP identify DBP5 and eIF3g as SLIP1-binding proteins. Nucleic acids research. 41(16):7960-71.
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 32 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.