Effect of phospholipid membranes on the specific and nonspecific transcription systems in vitro

Abstract

Effect of electroneutral monobilayered phosphatidylcholine vesicles (MPV) on DNA recognition by standardized RNA-polymerase preparations of prokaryotes (RNA polymerase II E. coli K12) or eukaryotes (RNA polymerase II in rat liver nuclei extracts) was investigated as well as kinetics of RNA synthesis on the matrix with analysis of controlled-size transcription products. The influence of phospholipid membranes on RNA synthesis in nonspecific transcription system was investigated on commercial preparation of K12 (incorporation of 14C-UMP in ENA) using electrophoresis radioautography technique. For the first time effect of membranes on DNA recognition by RNA-polymerase is studied in the system containing at least three types of macromolecules (DNA, protein, MPV) and metal (II) ions (Mg2+). The effect (rather complex) is shown to depend on DNA/membrane ratio and on Mg2+ ions concentration in solution and is observed in both specific and nonspecific transcription systems. For the first time it's shown that in specific system MPV increases accessibility of plasmid DNA for proteins: at 0°C topoisomerase (I) activity was observed and at 37°