REGULATION OF ANGR, A GENE WITH REGULATORY AND BIOSYNTHETIC FUNCTIONSIN THE PJM1 PLASMID-MEDIATED IRON UPTAKE SYSTEM OF VIBRIO-ANGUILLARUM

AngR and the product(s) encoded in the trans-acting factor (TAF) regio n are necessary for the full expression of the pJM1 plasmid-mediated a nguibactin iron-uptake system in Vibrio anguillarum (Va). In this repo rt, we analyzed the factors that affect the expression of the angR gen e. Northern blot analysis showed that angR encodes a 3.1-kb transcript which is expressed only under iron-limiting conditions. Measurement o f steady-state RNA levels show that, under iron-limiting conditions, a ngR is positively regulated at the transcriptional level by product(s) of the Va TAF region. However, this enhancement of angR expression by TAF does not occur at high levels of the AngR protein, as assessed by using an angR::lacZ fusion in the presence of a construct containing angR under the control of ptac. We also report that repression of angR by iron could possibly be mediated by an endogenous Va antisense RNA beta, which contains a stem-loop structure complementary to the stem-l oop structure located at the 5' end of angR.