Polyamine stimulation of the synthesis of oligopeptide-binding protein (OppA) - Involvement of a structural change of the Shine-Dalgarno sequence andthe initiation codon Aug in OppA mRNA
M. Yoshida et al., Polyamine stimulation of the synthesis of oligopeptide-binding protein (OppA) - Involvement of a structural change of the Shine-Dalgarno sequence andthe initiation codon Aug in OppA mRNA, J BIOL CHEM, 274(32), 1999, pp. 22723-22728
We previously suggested that the degree of polyamine stimulation of oligope
ptide-binding protein (OppA) synthesis is dependent on the secondary struct
ure and position of the Shine-Dalgarno (SD) sequence of OppA mRNA. To study
the structural change of OppA mRNA induced by polyamines and polyamine sti
mulation of initiation complex formation, four different 130-mer OppA mRNAs
containing the initiation region were synthesized in vitro. The structural
change of these mRNAs induced by polyamines was examined by measuring thei
r sensitivity to RNase T-1, specific for single-stranded RNA, and RNase V-1
, which recognizes double-stranded or stacked RNA. In parallel, the effect
of spermidine on mRNA-dependent fMet-tRNA binding to ribosomes was examined
. Our results indicate that the secondary structure of the SD sequence and
initiation codon AUG is important for the efficiency of initiation complex
formation and that spermidine relaxes the structure of the SD sequence and
the initiation codon AUG. The existence of a GC-rich double-stranded region
close to the SD sequence is important for spermidine stimulation of fMet-t
RNA binding to ribosomes, Spermidine apparently binds to this GC-rich stem
and causes a structural change of the SD sequence and the initiation codon,
facilitating an interaction with 30 S ribosomal subunits.