So far "broken" mRNAs lacking termination codons [6], [7], and mRNAs possessing inefficient termination codons [8], certain C-terminal codons [9], or containing rare codons [10] have been shown to elicit tmRNA tagging.
NSD was originally identified by following the degradation of transcripts lacking termination codons (Frischmeyer et al., 2002; van Hoof et al., 2002).
Although shortened on translation, the transcripts lacking termination codons were initially matured with poly(A) tails, making them indistinguishable from those seen in control cells.
Genomes lacking termination by TE still experience a pronounced delay in phage RNAP expression, however, because 330 sec is needed for host RNAP to reach the ectopic gene 1.
Reviewer's report Title: Structure based hypothesis of a mitochondrial ribosome rescue mechanism Version: 1 Date: 3 February 2012 Reviewer number 1, Dr. Eugene Koonin Report form: A very interesting hypothesis that mtRF1 is a constitutive peptidyl-tRNA hydrolase that rescues ribosomes stalled on aberrant mRNAs lacking termination codons in vertebrate mitochondria.
In addition, designing the forward primer within the open reading frame provides the 3′UTR with its natural gene-specific STOP codon at its 5′end, allowing convenient in-frame integration with the human ORFeome library, which instead lacks termination codons [ 16] (Fig. 1b).
Also identified were convergent genes that exhibit a lack of termination or a non-site-specific termination and the generation of rickettsial antisense RNAs resulting from the extension of transcripts into convergent gene sequences.
These analyses revealed that, rather than terminating at a specific site within the intervening region between the convergent genes, most of the transcripts demonstrated either a lack of termination within this region, which generated antisense RNA, or a putative non-site-specific termination that occurred throughout the intervening sequence.
The presence of rickettsial antisense RNAs generated by the lack of termination between convergent genes was an intriguing finding.
By contrast many dinoflagellate mitochondrial gene transcripts appear to lack any termination codon.
