Reactivation of denatured proteins by domain V of bacterial 23S rRNA.

In vitro transcripts containing domain V of the 23S rRNA of Escherichia coli and Bacillus subtilis can reactivate denatured proteins almost as efficiently as the total 23S rRNA. Here we show that almost the full length of domain V is required for reactivation of denatured pig muscle lactate dehydrogenase and pig heart cytoplasmic malate dehydrogenase: the central loop of this domain alone is not enough for this purpose. The antibiotic chloramphenicol, which binds to domain V of 23S rRNA, can inhibit reactivation of these proteins completely. Activity is eliminated by EDTA at a concentration of <1 mM, even in the presence of 4 mM MgCl2, suggesting that the three-dimensional conformation of the RNA should be maintained for this activity.