PROGRAMMED TRANSLATIONAL FRAMESHIFTING

Abstract

▪ Abstract Errors that alter the reading frame occur extremely rarely during translation, yet some genes have evolved sequences that efficiently induce frameshifting. These sequences, termed programmed frameshift sites, manipulate the translational apparatus to promote non-canonical decoding. Frameshifts are mechanistically diverse. Most cause a −1 shift of frames; the first such site was discovered in a metazoan retrovirus, but they are now known to be dispersed quite widely among evolutionarily diverse species. +1 frameshift sites are much less common, but again dispersed widely. The rarest form are the translational hop sites which program the ribosome to bypass a region of several dozen nucleotides. Each of these types of events are stimulated by distinct mechanisms. All of the events share a common phenomenology in which the programmed frameshift site causes the ribosome to pause during elongation so that the kinetically unfavorable alternative decoding event can occur. During this pause most framesh...