DNA-dependent RNA polymerase (RNAP) catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. a ribonucleoside 5'-triphosphate + RNA(n) = diphosphate + RNA(n+1) Binds 1 zinc ion. Part of the RNA polymerase complex. Belongs to the archaeal Rpo12/eukaryotic RPC10 RNA polymerase subunit family.