Fig. 2.

Properties of WT and mutant GreB factors. (A) Transcript cleavage activity. [³²P]-labeled TEC-13 obtained as described above was incubated in the absence or in the presence of indicated concentrations of GreB in TB. The original 13-nt RNA as well as 2- and 3-nt cleavage product are marked. (B) Crosslinking of Gre factors in TEC-14 containing photoreactive group (reagent I, see Fig. 3B) attached to the 3′ terminal RNA residue. The position of the crosslinked GreB and RNAP β- and β′-subunits are indicated. (C and D) The rate of RNA degradation in TEC13 in the absence or in the presence of Gre at indicated concentrations of Mg²⁺.