Transcription-repair coupling factor

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The bacterial transcription-repair coupling factor TRCF, also called Mfd translocase, is a DNA repair protein. It has a role in transcription-coupled repair, a subpathway of nucleotide excision repair (NER). Mfd recognizes stalled RNA polymerase (RNAP) and either restarts transcription or removes the stalled polymerase and recruits the NER proteins UvrA and UvrB.

Function

Mfd has ATP hydrolysis activity, DNA binding sites and a UvrA binding sites. These three functions are inhibited in the isolated enzyme, but are activated when Mfd encounters stalled RNA polymerase (or through various mutations that remove inhibitory domains [1]). Mfd also contains an RNA interaction domain (RID) that binds to the beta subunit of RNAP.

Relationship to other enzymes

The N-terminal part of Mfd shows sequence similarity to UvrB, including in the domain of UvrB that interacts with UvrA. However, the conserved helicase motifs present in UvrB (responsible for binding and hydrolyzing ATP) are absent in that part of Mfd. Furthermore, the sequence segment known to fold as a beta hairpin in UvrB (involved in clamping down a single strand of DNA) seems absent. The C-terminal part of Mfd shows sequence similarity to SF1/SF2 helicases (UvrB is an example), containing conserved helicase/translocase motifs.

Structure and conformational change

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Created with the participation of Wayne Decatur

Proteopedia Page Contributors and Editors (what is this?)

Karsten Theis, Michal Harel, Alexander Berchansky, Wayne Decatur

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