Sequences in certain mRNAs program the ribosome to
undergo a noncanonical translation event, translational
frameshifting, translational hopping, or termination readthrough.
These sequences are termed recoding sites, because they
cause the ribosome to change temporarily its coding rules.
Cis and trans-acting factors sensitively
modulate the efficiency of recoding events. In an attempt
to quantitate the effect of these factors we have developed
a dual-reporter vector using the lacZ and luc
genes to directly measure recoding efficiency. We were
able to confirm the effect of several factors that modulate
frameshift or readthrough efficiency at a variety of sites.
Surprisingly, we were not able to confirm that the complex
of factors termed the surveillance complex regulates translational
frameshifting. This complex regulates degradation of nonsense
codon-containing mRNAs and we confirm that it also affects
the efficiency of nonsense suppression. Our data suggest
that the surveillance complex is not a general regulator
of translational accuracy, but that its role is closely
tied to the translational termination and initiation processes.