Mfd is the transcription-coupling repair factor, which coalesces a stalled RNAP with the Nucleotide Excision Repair (NER) pathway to preferentially repair lesions in the template strand of actively transcribed genes before lesions in the coding strands or in non-actively transcribed genes. Studies suggest that Mfd influences phenotypes unrelated to transcription-coupled repair. Reports showed that Mfd affects carbon catabolite repression of operons. In addition, in vitro studies show that Mfd can facilitate repression of transcription by roadblock clearance of genes regulated by the global transcription regulators such as CodY. Our lab demonstrated a role for Mfd in the expression of amino acid biosynthesis genes and protection from oxidative stress.