Induces RNA cleavage activity in the RNA polymerase. In its presence, the cleavage activity of the RNA polymerase truncates the RNA back to position +15 in a stepwise manner by releasing mainly dinucleotides from the 3'-end of the nascent RNA. The truncated RNAs are able to continue elongation. Involved in transcriptional proofreading and fidelity. Misincorporation of nucleotides during elongation of transcription leads to arrested elongation complexes which are rescued by TFS-promoted removal of a dinucleotide from the 3'-end. TFS is able to induce a cleavage resynthesis cycle in stalled elongation complexes (resulting from the next missing nucleotide or a reduced incorporation rate of a wrong nucleotide) preventing misincorporation and enabling proofreading in a post-incorporation manner. Pausing of elongation complexes is the main determinant of TFS-induced RNA cleavage. Belongs to the archaeal RpoM/eukaryotic RPA12/RPB9/RPC11 RNA polymerase family. More similar by sequence similarity to the eukaryotic RNA polymerase subunits.