Extensive antisense transcription in Azoarcus olearius strain BH72

Our recent directional RNA-Seq analysis detected widespread presence of reads mapping in the antisense orientation to the annotated genes. Although this has been discovered for several bacteria, the stable expression and functional relevance of such antisense RNAs (asRNAs) are still being debated.

In this study we ventured to confirm the single-cell expression and unravel the functionality of antisense transcription in strain BH72. First, from the directional RNA-Seq data we predicted 798 asRNAs that were encoded against 709 genes (18 % of the annotated genome). Using a cassette encoding for two fluorescent reporters (GFP and TdTomato), in convergent orientation with transcriptional terminators in between, we were able to confirm the single-cell co-expression of both the sense and the antisense transcripts within azo1349 in at least 90 % of the bacterial population.