FIG. 5.

Effect of temperature on the NP-RNA interaction. (a and b) MBP-NP fusion proteins were prepared from E. coli cultures grown at the indicated temperatures and assayed for their ability to bind a radiolabelled RNA as in Fig. 4. (a and b) The autoradiogram (a) and the equivalent Coomassie brilliant blue-stained gel (b) are presented. (c) Thermal denaturation of RNA-binding activity. The indicated polypeptides (100 nM) were tested for their ability to bind a radiolabelled RNA (1 nM) at the indicated temperatures by filtration through a nitrocellulose filter. Protein was heated in the presence (solid symbols) or absence (open symbols) of RNA. Values are plotted as a percentage of the amount bound by each protein at 30°C.