Nonsense-mediated decay mutants do not affect programmed −1 frameshifting
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.(Received February 28 2000)
(Revised March 15 2000)
(Accepted April 10 2000)
Key Words: HIV; PSI; recoding; release factor; reporter; UPF.
c1 Reprint requests to: Philip J. Farabaugh, Department of Biological Sciences and Program in Molecular and Cell Biology, University of Maryland, Baltimore County, Baltimore, Maryland 21250, USA; e-mail: [email protected].
1 These authors contributed equally to this work.