INFLUENCE OF THE SEQUENCE FLANKING DOWNSTREAM THE -10-HOMOLOGY REGIONOF SPC PROMOTER ON INTERACTION WITH ESCHERICHIA-COLI RNA-POLYMERASE

To examine the influence of nucleotide sequences flanking downstream t he -10 homology region of Escherichia coli gene promoters on the inter action with E. coli RNA polymerase [EC 2.7.7.6], the apparent dissocia tion constants were determined for enzyme complexes with oligonucleoti des identical to the spc promoter flanking region and those containing G(6), G(6), A(6), and T-6 stretches. The dissociation constants for c omplexes with single-stranded oligonucleotides containing A and T site s were 4-6 times higher than for oligonucleotides with G,C sites. It w as found that the affinity for RNA polymerase is determined by the con sensus site of the -10 homology region. Replacement of the natural seq uence TATAAT in the untranscribed DNA strand with the complementary AT ATTA decreased the affinity by two orders of magnitude.