ABSTRACT
Methylation protection experiments with four promoters (P1 and P2 of the pBR322 plasmid, lacUV5 and lambda P0) have shown that the RNA polymerases from Escherichia coli and Pseudomonas putida, while differing in the primary structure of the subunits involved in DNA binding, display identical patterns of DNA contacts. Nor do these enzymes differ in covalent cross-linking patterns with a partially apurinized promoter. We conclude that the two RNA polymerases have very similar structures of DNA binding centers. The evolutionary conservation of this structure may account for the fact that diverse RNA polymerases often recognize and efficiently use promoters of distant bacterial species.
Subject(s)
DNA-Directed RNA Polymerases/genetics , Escherichia coli/genetics , Operon , Pseudomonas/genetics , Bacteriophage lambda/genetics , Base Sequence , DNA, Bacterial/metabolism , DNA, Viral/genetics , Escherichia coli/enzymology , Escherichia coli/metabolism , Methylation , Pseudomonas/enzymology , Pseudomonas/metabolism , Purines/metabolism , Transcription, GeneticABSTRACT
We have developed a method to localize specific sites where RNA elongation is arrested due to DNA-bound ligands. The method was used to determine apparent binding sites for actinomycin D. We have found 14 strong RNA hindrance sites along nucleotide sequence of T7 and D111 T7 DNA of 380 nucleotides full length under low actinomycin D concentration conditions. Nucleotide sequence of all the sites is described by general formula XGCY where X not equal to G and Y not equal to C.
