ARS | Publication request: Transcription termination Within the iron transport-biosynthesis operon of Vibrio anguillarum requires an antisense RNA

Submitted to: Journal of Bacteriology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 23, 2007
Publication Date: May 1, 2007
Citation: Stork, M., Di Lorenzo, M., Welch, T.J., Crosa, J. 2007. Transcription termination Within the iron transport-biosynthesis operon of Vibrio anguillarum requires an antisense RNA. Journal of Bacteriology 189:(9), 3479-88.

Interpretive Summary: Vibrio anguillarum is a marine bacterium that causes a highly lethal disease in a variety of fishes including cultured salmonids. This bacterium’s ability to cause disease is dependent on a highly-regulated iron scavenging system. This study reports a novel mechanism for the regulation of the iron scavenging system produced by this organism. The mechanism involves an RNA molecule that modulates the expression of components of this system. This novel finding broadens our understanding of the regulation of virulence in bacterial fish pathogens and may be useful in the design of safe vaccines.

Technical Abstract: The iron transport-biosynthesis (ITB) operon in Vibrio anguillarum includes four genes for ferric-siderophore transport, fatD,C,B,A, and two genes for siderophorebiosynthesis, angR and angT and plays an important role in the virulence mechanism of this bacterium. Despite being part of the same polycistronic mRNA, the relative levels of transcription for the fat and for the whole ITB message differ profoundly, the levels of the fat transcript being about 17-fold higher. Using S1 nuclease mapping, lacZ transcriptional fusions and in vitro studies we were able to show that the differential gene expression within the ITB operon is due to termination of transcription between the fatA and angR genes, although a few transcripts proceeded beyond the termination site to the end of this operon, thus transcribing both angR and angT. This termination process requires a 427- nucleotide antisense RNA that spans the intergenic region and acts as a novel transcriptional terminator.