DNA-dependent RNA polymerase (RNAP) catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Forms part of the jaw domain. a ribonucleoside 5'-triphosphate + RNA(n) = diphosphate + RNA(n+1) Part of the 13-subunit RNA polymerase complex. Corresponds to about the last third of the bacterial beta' subunit. Belongs to the RNA polymerase beta' chain family.