Figure 4.

A carboxy-terminally truncated NusA binds specifically to nut-site RNA. (A) RNA binding by NusA (amino acids 1–416) is prevented by a mutation in the boxA portion of the nut site. Reactions containing wild-type or mutant ³²P-labeled nut-site RNA (as indicated) and 3.5, 7, or 14 μM NusA or NusA (amino acids 1–416) (as indicated) were electrophoresed on 7.5% nondenaturing gels, dried, and exposed to film. (B) RNA binding by NusA (amino acids 1–416) is stabilized by amino acids 1–137 and 348–415 of NusA. Reactions containing ³²P-labeled nut-site RNA and 10 μM NusA (amino acids 132–416), NusA (amino acids 132–495), NusA (amino acids 1–348), NusA (amino acids 1–416) or NusA (as indicated) were electrophoresed on 7.5% nondenaturing gels, dried, and exposed to film.