question: Which proteins act as factors that promote transcription-coupled repair in bacteria?
answer: Transcription coupled nucleotide excision repair (TC-NER or TCR) is a cellular process by which UV-induced damage and other road-blocks encountered in the transcribed strand are restored. Bacterial transcription-coupled repair is initiated when RNA polymerase stalled at a DNA lesion is removed by Mfd (Mutation frequency decline), an ATP-dependent DNA translocase. Mfd is the major transcription repair coupling factor in bacteria. Also, the transcription elongation factor NusA, in addition to its role in recruiting translesion synthesis (TLS) DNA polymerases to gaps encountered during transcription,  promotes an alternative class of TCR involved in the identification and removal of a class of lesion, such as the N(2)-f-dG lesion.