FIG 6.

Effect of Hfq on sRNA-mRNA duplex stability. (A) Addition of 0 to 100 nM PrrF1 sRNA to 5 nM ³²P-labeled antR mRNA produces PrrF1-antR mRNA duplex. (B) A fraction of PrrF1-antR mRNA duplex (Fig. 5A) with increasing PrrF1 concentrations was fit to a 2-state quadratic equation (equation 3). (C) A preformed complex of 5 nM ³²P-antR mRNA and 10 nM PrrF1 sRNA was titrated with 0 to 200 nM Hfq₆ to compare the stabilities of the RNA duplex at different Hfq concentrations. An increase in the Hfq concentrations resulted in an increase of antR-PrrF1 (A-P1) band intensity up to 50 nM. A stable ternary complex (antR-PrrF1-Hfq) was visible above 50 nM Hfq₆. High Hfq concentrations destabilized the antR-PrrF1 duplex, resulting in free antR RNA. (D) The fraction of antR mRNA-PrrF1 complexes as a function of the Hfq concentration was fit to equation 4.