1 research outputs found
Evidence for Context-Dependent Complementarity of Non-Shine-Dalgarno Ribosome Binding Sites to <i>Escherichia coli</i> rRNA
While the ribosome has evolved to
function in complex intracellular
environments, these contexts do not easily allow for the study of
its inherent capabilities. We have used a synthetic, well-defined <i>Escherichia coli</i> (<i>E. coli</i>)-based translation
system in conjunction with ribosome display, a powerful <i>in
vitro</i> selection method, to identify ribosome binding sites
(RBSs) that can promote the efficient translation of messenger RNAs
(mRNAs) with a leader length representative of natural <i>E.
coli</i> mRNAs. In previous work, we used a longer leader sequence
and unexpectedly recovered highly efficient cytosine-rich sequences
with complementarity to the 16S ribosomal RNA (rRNA) and similarity
to eukaryotic RBSs. In the current study, Shine-Dalgarno (SD) sequences
were prevalent, but non-SD sequences were also heavily enriched and
were dominated by novel guanine- and uracil-rich motifs that showed
statistically significant complementarity to the 16S rRNA. Additionally,
only SD motifs exhibited position-dependent decreases in sequence
entropy, indicating that non-SD motifs likely operate by increasing
the local concentration of ribosomes in the vicinity of the start
codon, rather than by a position-dependent mechanism. These results
further support the putative generality of mRNA-rRNA complementarity
in facilitating mRNA translation but also suggest that context (e.g.,
leader length and composition) dictates the specific subset of possible
RBSs that are used for efficient translation of a given transcript