J. Mogridge et al., INDEPENDENT LIGAND-INDUCED FOLDING OF THE RNA-BINDING DOMAIN AND 2 FUNCTIONALLY DISTINCT ANTITERMINATION REGIONS IN THE PHAGE-LAMBDA N-PROTEIN, MOLECULAR CELL, 1(2), 1998, pp. 265-275
The transcriptional antitermination protein N of bacteriophage lambda
binds the boxB component of the RNA enhancer nut (boxA + boxB) and the
E. coli elongation factor NusA. Efficient antitermination by N requir
es an RNA-binding domain (amino acids 1-22) and two activating regions
for antitermination: a newly identified NusA-binding region (amino ac
ids 34-47) that suppresses NusA's enhancement of termination, and a ca
rboxy-terminal region (amino acids 73-107) that interacts directly wit
h RNA polymerase. Heteronuclear magnetic resonance experiments demonst
rate that N is a disordered protein. Interaction with boxB RNA induces
only the RNA-binding domain of N to adopt a folded conformation, whil
e the activating regions of the protein remain disordered in the absen
ce of their target proteins.