HETEROGENEITY OF RNA POLYMERASE IN MYCOBACTERIUM TUBERCULOSIS H37Rv

Abstract

Crude extracts of M. tuberculosis cells were fractionated on sucrose gradients of low ionic strengths. In contrast to the sedimentation behaviour of the purified enzyme, the RNA polymerase activity in the crude extracts sedimented heterogeneously over a wide range of the gradient. On raising the ionic strength, the RNA polymerase activity sedimented as two distinct peaks. These two peaks of activity were shown to have different thermal stability, rifampicin sensitivity and affinity for substrates. It is suggested that this physical and functional heterogeneity might have biological significance.