[Conformational analysis of complexes of RNA polymerase from Escherichia coli with DNA]

Conformational behaviour of T2 DNA during its complex formation with E.coli RNA polymerase was studied by spin label technique. T2 DNA was selectively modified at its readily melting AT-rich sites by bromoacetooxypiperidine-1-oxyl-radical. Specific conformational changes are induced in DNA structure by RNA polymerase attachment. The changes are observed under the conditions when open transcriptionally competent complexes are formed. The readily melting sites of T2 DNA were shown to be involved in the formation of functionally active promoters.