FIG 7.

UL21 binds E. coli RNA. (A) Purified StII-GS-UL21 expressed in E. coli appears homogenous as judged by SDS-PAGE and Coomassie staining but has an A₂₆₀/A₂₈₀ ratio consistent with a large amount of nucleic acid contaminant. (B) UL21 binds heparin Sepharose and is eluted with increasing NaCl concentrations (shown as conductivity). (C) Heparin Sepharose purification produces pure UL21 free of nucleic acid contamination as judged by the A₂₆₀/A₂₈₀ ratio and SDS-PAGE. (D) The copurified nucleic acids are susceptible to digestion with RNase but not DNase. Samples were resolved on an ethidium bromide-stained formaldehyde agarose gel.