Differential pressure resistance in the activity of RNA polymerase isolated from Shewanella violacea and Escherichia coli

RNA polymerase was purified from the piezophile Shewanella violacea DSS12, and the transcriptional activity after pressure treatment was compared with that of the mesophile Escherichia coli. Application of pressure at 100 MPa for 30 min reduced the E. coli RNA polymerase activity to 60% of the activity at atmospheric pressure, whereas the S. violacea RNA polymerase maintained full activity, indicating that the S. violacea RNA polymerase is more stable than its E. coli counterpart. This result was supported by the analysis of the strength of subunit interactions of the enzyme from both species, using a high-pressure electrophoresis apparatus, which showed that a pressure of 140 MPa caused dissociation of E. coli RNA polymerase but not that of S. violacea RNA polymerase. On the other hand, the core enzyme of S. violacea RNA polymerase, which lacked the σ70 factor, was dissociated at 140 MPa. These results suggest that the σ70 factor is required for stabilization of S. violacea RNA polymerase under high-pressure conditions. In this paper, we provide in vitro evidence for piezoadaptation at the transcriptional level, using purified RNA polymerase from cells of S. violacea and E. coli.