The binding of Class II sRNA MgrR to two different sites on matchmaker protein Hfq enables efficient competition for Hfq and annealing to regulated mRNAs

Global modeling of MgrR annealing to ygdQ145 in the presence of wt Hfq. The native gel analysis of the kinetics of (i) ³²P-labeled MgrR annealing to ygdQ145 in the absence of Hfq (A) or the presence of wt Hfq (C), and (ii) ³²P-labeled ygdQ145 annealing to MgrR in the absence of Hfq (B) or the presence of wt Hfq (D). The data from A, B, C, and D were analyzed globally, and the lines in the plots are the results of global fitting. The schemes on the right of the plots in C and D describe kinetically preferred competing pathways (blue arrows) based on the data from Table 4. Unbound MgrR is marked as M, unbound ygdQ145 as Y, MgrR-ygdQ145 complex as MY, MgrR-Hfq complex as MH, ygdQ145-Hfq complex as HY, and MgrR-ygdQ145-Hfq ternary complex as MYH.