Isolation and physical properties of the DNA-directed RNA polymerase from Thermus thermophilus HB8.

The DNA-directed RNA polymerase from the extremely thermophilic eubacterium Thermus thermophilus HB8 was purified employing a new and rapid method. The subunit pattern of the enzyme, analyzed by SDS gel electrophoresis, was interpreted as: 140 kDa and 170 kDa for beta and beta', 40 kDa for alpha and 92 kDa for sigma. The RNA polymerase is active at elevated temperatures (65 degrees C). Kinetic data provide evidence for the existence of two NTP binding sites with very strong cooperativity. The promoter site specificity of the isolated enzyme has been proven by in vitro transcription employing two T. thermophilus templates whose in vivo starts of transcription were characterized by nuclease S1 mapping.