FIGURE 6.

Importance of individual nucleotide alterations around the editing site. The influence of the identity of the first nucleotide downstream of the edited nucleotide was determined by mutating this position through all three alternative nucleotides. Any of these changes results in the loss of ~70% of the editing activity. All mutants were tested in four separate experiments, and the mean percentages of the wild-type editing activity were determined. The resulting standard error is indicated for each mutant. The tolerance of the in vitro editing activity for distance alterations between the upstream cis-recognition element and the edited nucleotide was investigated by deleting or inserting an adenosine nucleotide within the run of four As in the wild-type sequence. No activity was observed with either template, showing that the distance from the cis-element is crucial. Please note that in the deletion template a concomitant A-to-G change at the +1 position has occurred.