Studies on the transcription complex of Escherichia coli RNA polymerase

To study the chain elongation phase of enzymatic RNA synthesis ternary transcription complexes with T7 DNA or poly[dA) - (dT)] as template were isolated by gel exclusion chromatography. The DNA in these complexes contains single-stranded regions which are recognized by a single-strand-specific nuclease from Neurospora crassa. The non-codogenic DNA strand in the poly[(dA) - (dT)] ternary complex is preferentially hydrolysed by the nuclease. The polymerase protects predominantly the codogenic strand in this complex from digestion by DNAse I. In the T7 DNA ternary complex a DNA fragment with a chain length of approximately 26 nucleotides and an RNA fragment of about 22 nucleotides are protected by polymerase from digestion by DNAse and RNAse.