ESCHERICHIA-COLI RNA-POLYMERASE INTERACTION WITH THE OLIGORIBONUCLEOTIDES HOMOLOGOUS TO -10-REGION AND -35-REGION OF BACTERIAL SPC PROMOTERS

It has been shown earlier that E. coli RNA polymerase [EC 2.7.7.6] is able to recognize with high selectivity and bind oligodeoxyribonucleot ides 12-14 residues long, structurally similar to the ''-10'' region o f bacterial promoters of the nontranscribed DNA strand, including the Pribnow box and the flanking nucleotides up to the transcription initi ation site. Such affinity oligodeoxyribonucleotides (ODRN) are able to inhibit competitively bacterial DNA transcription catalyzed by E. col i RNA polymerase [L K. Savinkova et al., Mol Biol., 22, 807 (1988)]. I n the present paper we demonstrate that the E. coli RNA polymerase is unable to bind oligoribonucleotides (ORN) which are homologous to such an affinity ODRN, structurally similar to the ''-10'' region of the s pc promoter, but can bind the ORN complementary to it. These ORN are a lso able to inhibit competitively the transcription of bacterial DNA. Attachment of alkylating residues to the 5' ends of the affinity oligo deoxy- and oligoribonucleotides promotes their covalent binding to E. coli RNA polymerase. We found that the modified affinity ODRN interact s with the sigma subunit, and the modified affinity ORN with the beta' beta subunit of the E. coli polymerase. It is suggested that such an O RN may be transcribed in a region of the nontranscribed DNA strand wit hin the open promoter complex, and may function as a detached primer o r a transcription regulator.