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 RNA polymerase complex (PubMed:21386817). An artificial construct of the RNAP clamp domain (including part of this protein) contacts transcription elongation factors Spt4 and Spt5 (PubMed:21386817). Belongs to the RNA polymerase beta' chain family.