DNA-Dependent RNA Polymerase from an Extremely Halophilic Bacterium

Abstract

<p> This thesis describes the isolation and investigation of a DNA-dependent RNA polymerase from the extreme halophile Halobacterium cutirubrum.</p> <p> The enzyme system was analyzed under conditions of very high ionic strengths which are characteristic of the internal salt concentrations of extreme halophiles and at much lower ionic strengths found in conventional bacterial systems. The enzyme was found to have activity in a wide range of salt concentrations when attached to its DNA template in the form of a DNA-Membrane-Protein complex. The enzyme, however, lost the ability to function at high ionic strengths when freed from this complex.</p> <p> The properties of the isolated DNA-dependent RNA polymerase from the halophile were then compared to the properties of the same enzyme isolated from the non-halophilic bacterium, Eschericia coli. Both enzymes were found to have the same approximate molecular weights and to share the same substrate requirements. The enzymes differed, however, in their response to inhibitors specific for RNA synthesis. </p>