Figure 2.

Representative intrinsic TFQ titration experiment. To provide the initial value of tryptophan fluorescence, 1 μM Hfq mutant F42W in the absence of RNA was excited at 298 nm and the emission scanned from 320–400 nm. The maximum fluorescence intensity is found at 343 nm (denoted by a solid vertical red line). RNA quenching of the tryptophan fluorescence is calculated by measuring the intensity differences at wavelength 343 nm after addition of an RNA aliquot, employing the equation Quenching (%) = (1 − ((F_R−F_B)/(F₀−F_B))) × 100, and carrying out the appropriate corrections as described in the ‘Materials and Methods’ section.