Angular alteration of the DNA helix by E. coli RNA polymerase.

Abstract

IT has been a source of speculation whether the reading of the genetic code of DNA by RNA polymerase involves the disruption of the DNA helix. While circuitous evidence favouring either affirmative or negative answer has been accumulating, direct experiments have been few1–11. Kosaganov et al. investigated the possibility of a local unwinding of DNA during RNA synthesis by measuring the kinetics of formaldehyde-induced denaturation of DNA during RNA synthesis12. They concluded that the binding of RNA polymerase did not cause local unwinding but RNA synthesis produced “defects” in the double helix. Unfortunately, the interpretation of formaldehyde-induced denaturation is not clear, nor is the nature of a “defect”.