Antisense RNA, fur, iron, and the regulation of iron transport genes in Vibrio anguillarum

Abstract

The negative regulation of the expression of iron transport genes fatA and fatB in Vibrio anguillarum is mediated by a chromosome-encoded Fur protein and a plasmid pJM1-derived antisense RNA (RNAα), which is preferentially expressed under iron-rich conditions. In this work, we characterized the RNAα promoter region, and by using promoter fusion and rifampicin experiments we were able to demonstrate that iron regulates RNAα synthesis posttranscriptionally by stabilizing RNAα half-life rather than enhancing transcription initiation. The Fur protein is also essential for RNAα synthesis at the transcription initiation level, independently of the iron status of the cell. From experiments assessing the relative contribution of Fur and RNAα, we were able to show that RNAα may indeed play an important role on the negative regulation of the expression of the iron transport genes under physiological conditions.