Effect of mic gene structure on repressor activity in the OmpA system.

It has been previously established that micRNA (mRNA-interfering complementary RNA) complementary to an individual mRNA specifically represses the expression of the target mRNA. We have constructed several plasmids which produce micRNAs which are complementary to different regions of the ompA mRNA. The repressor activity of these different micRNAs has been compared to determine the role of mic gene structure in effective micRNA function. The results indicate that micRNAs complementary to regions of the ompA mRNA likely to encounter ribosomes have the highest repressor activities. A clear effect of mic gene dosage was also observed. This was demonstrated using both identical and different mic(ompA) genes.