Transcription-repair coupling factors TRCFs

Transcription stimulates excision repair both in E. coli (Mellon and Hanawalt, 1989) and in humans (Bohr et al., 1985 Mellon et at, 1987) in a process dependent on proteins called transcription-repair coupling factors (TRCFs). In E. coli the mfd gene encodes the TRCF (Selby and Sancar, 1991,1993 Selby etaZ., 1991), and cells mutated in this gene exhibit modest UV sensitivity but a disproportionately increased rate of UV-induced mutations and lack of mutation frequency decline (mfd) on holding in minimal medium after irradiation and before plating (Witkin, 1994). 

Fig. 5. Model for transcription-coupled repair in E. coli. A lesion in the nontranscribed (NT) strand has no effect on RNA polymerase (RNAP) (left side), but a lesion in the transcribed strand blocks progression of RNAP (right). Transcription-repair coupling factor (TRCF) recognizes and binds to the stalled...

---