The 30S subunit either dissociates spontaneously from the previously bound mRNA or scans the mRNA to resume translation at a nearby initiation site While this sequence of termination events is important for the recycling of ribosomes, it is obstructed when the ribosomes stall at the ends of truncated mRNAs lacking a termination codon.
During translation elongation when ribosomes encounter a termination codon, the sequence of events (reviewed in [34]) that lead to polypeptide release and recycling of the ribosome is initiated by polypeptide release factors RF1 (UAG/UAA) or RF2 (UGA/UAA).
In contrast, the RI class rarely changed the frame (6.1%) of translation, largely because the RI class led to the incorporation of a termination codon in the sequence of the retained intron.
Termination codons in mRNA molecules are typically specified directly by the sequence of the corresponding gene.
Moreover, stop codon bias and context also correlates with the efficiency of translation [ 23], so the preferred sequence of translation termination in E. coli, 'TAAT' was used.
Further development of the sequence termination criteria could improve the proportion of segments that are identified by the algorithm.
The transgenic state of ten independent plants (four with the DefH9-RI-iaaM gene containing the termination sequence of the nos gene, and six with the termination sequence of the rolC gene) was analysed by Southern blot analysis (Fig. 2b).
To do this, we introduced 6 nt deletions throughout the length of the sequence upstream of the M1 termination codon in the context of the BM2 termination-reinitiation reporter plasmid, p2luc-BM2-204 (Figure 1A; [1A]).
A total of 44 tomato UC82 plants transgenic for the DefH9-RI-iaaM gene were raised by using two versions of the gene (DefH9-RI-iaaM C and DefH9-RI-iaaM S) identical except for the termination sequences (i.e. 32 plants with termination sequences of the rolC gene and 12 plants with the termination sequence of the nos gene).
To obtain transgenic Arabidopsis plants, the coding sequence of the TaNAC29 containing termination codon was amplified by RT-PCR and cloned into XbaI/ SmaI restriction sites of the pBI121 vector (Clontech) under the control of the 35S promoter of cauliflower mosaic virus.
