Résumé
We analysed complexes formed during recognition of the lacUV5 promoter by E.coli RNA polymerase using formaldehyde as a DNA - protein and protein - protein cross-linking reagent. Most of the cross-linked complexes specific for the open complex (RPO) contain the β′ subunit of RNA polymerase cross-linked with promoter DNA in the regions: - 50 to - 49; - 5 to -10; +5 to +8 and +18 to +21. The protein - protein cross-linking pattern of contacting subunits is the same for the RNA polymerase in solution and in RP0: there are strong α-β′ and β-β′ interactions. In contrast, only β-β′ cross-links were detected in the closed (RPc) and intermediate (RPl) complexes. In presence of lac repressor before or after formation of the RPo crosslinking pattern is similar with that of RPl (RPc) complex.