ANTISENSE RNA, FUR, IRON, AND THE REGULATION OF IRON TRANSPORT GENES IN VIBRIO-ANGUILLARUM

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