Читать книгу The New Microbiology - Pascale Cossart - Страница 17

Some RNAs function both as antisense and as messenger. They are encoded in recently discovered regions of bacterial chromosomes called excludons. These regions were originally detected in the Listeria genome but were then found to exist in various other bacteria. Excludons are made up of two DNA regions encoding genes or operons that are oriented in opposition to one another on the bacterial chromosome. They encode a long RNA (up to 6,000 nucleotides) that is antisense to one of the regions. The first part of this RNA functions as an actual antisense that has a negative effect on the genetic expression of the gene or operon located on the strand opposite to the one that codes the RNA. But the second part of the RNA can act as an mRNA (Fig. 8).

Figure 8. Example of an excludon. Once the transcription beginning at P2 is expressed and generates a long transcript, the operon on the right becomes less expressed.