Figure 3. NusG stimulates termination through its role as a sequence-specific pause factor.

(A) KtrD terminator showing the points of termination (POT₁ and POT₂) and pause sites (Pause₁ and Pause₂) identified in vitro. The POT identified in vivo by Term-seq is also specified (POT_Term-seq). The upstream A tract is also shown. The average half-life (T_1/2) of each pause ± standard deviation based on in vitro pausing data are specified to the right of each pause in parentheses. (B) Single-round in vitro pausing and termination assay using the wild-type (WT) ktrD terminator ± NusG. Time points of elongation are indicated above each lane. T, 30 min termination assay. RNA sequencing lanes (U, G, A, C) are labeled. Positions of NusG-dependent pause bands, termination sites, and run-off (RO) transcripts are marked. (C, D) Identical to (A–B) except that it is the C5U:A6U mutant ktrD terminator. The WT (A) and mutated (C) residues are highlighted in red.