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The 3.2 A-resolution X-ray crystal structure of Escherichia coli transcription-repair coupling factor (TRCF) is discussed. A compact arrangement of eight domains, a translocation module and a region of structure similarity to UvrB is observed in the structure.

DNA damage that blocks the transcription of genes is prioritized for repair by transcription-coupled DNA repair pathways. RNA polymerases stalled at DNA lesions obstruct repair enzymes, but this situation is turned to the advantage of the cell by transcription-repair coupling factors that remove the stalled RNA polymerase from DNA and increase the rate at which the lesion is repaired. Recent structural studies of the bacterial transcription-repair coupling factor, Mfd, have revealed a modular architecture in which an ATP-dependent DNA-based motor is coupled to protein–protein interaction domains that can attach the motor to RNA polymerase and the DNA repair protein UvrA. Here I review the key features of this multifunctional protein and discuss how recent mechanistic and structural findings have advanced our understanding of transcription-coupled DNA repair in bacteria. [Copyright &y& Elsevier]