Instability of Rickettsia prowazekii RNA polymerase-promoter complexes

The procaryotic RNA polymerase of the obligate intracellular parasite Rickettsia prowazekii was compared with Escherichia coli's sigma-70, focusing on their behavior during the start of transcription. While E. coli's RNA polymerase-promoter complexes remained stable, R. Prowazekii's complexes were unstable, dissociable and reactive to heparin. Heparin sensitivity was regulated mainly by the R. prowazekii core.