scholarly journals Structural basis for transcription complex disruption by the Mfd translocase

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jin Young Kang ◽  
Eliza Llewellyn ◽  
James Chen ◽  
Paul Dominic B Olinares ◽  
Joshua Brewer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Polymerase ◽  
Nucleotide Excision Repair ◽  
Bound States ◽  
Excision Repair ◽  
Structural Basis ◽  
Template Strand ◽  
Cryo Electron Microscopy ◽  
Nucleotide Excision ◽  
Transcription Coupled Repair

Transcription-coupled repair (TCR) is a sub-pathway of nucleotide excision repair (NER) that preferentially removes lesions from the template-strand (t-strand) that stall RNA polymerase (RNAP) elongation complexes (ECs). Mfd mediates TCR in bacteria by removing the stalled RNAP concealing the lesion and recruiting Uvr(A)BC. We used cryo-electron microscopy to visualize Mfd engaging with a stalled EC and attempting to dislodge the RNAP. We visualized seven distinct Mfd-EC complexes in both ATP and ADP-bound states. The structures explain how Mfd is remodeled from its repressed conformation, how the UvrA-interacting surface of Mfd is hidden during most of the remodeling process to prevent premature engagement with the NER pathway, how Mfd alters the RNAP conformation to facilitate disassembly, and how Mfd forms a processive translocation complex after dislodging the RNAP. Our results reveal an elaborate mechanism for how Mfd kinetically discriminates paused from stalled ECs and disassembles stalled ECs to initiate TCR.

scholarly journals Structural basis for transcription complex disruption by the Mfd translocase

2020 ◽  
Author(s):  
Jin Young Kang ◽  
Eliza Llewellyn ◽  
James Chen ◽  
Paul Dominic B. Olinares ◽  
Joshua Brewer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rna Polymerase ◽  
Nucleotide Excision Repair ◽  
Bound States ◽  
Excision Repair ◽  
Structural Basis ◽  
Template Strand ◽  
Cryo Electron Microscopy ◽  
Nucleotide Excision ◽  
Transcription Coupled Repair

SummaryTranscription-coupled repair (TCR) is a sub-pathway of nucleotide excision repair (NER) that preferentially removes lesions from the template-strand (t-strand) that stall RNA polymerase (RNAP) elongation complexes (EC). Mfd mediates TCR in bacteria by removing the stalled RNAP concealing the lesion and recruiting Uvr(A)BC. We used cryo-electron microscopy to visualize Mfd engaging with a stalled EC and attempting to dislodge the RNAP. We visualized seven distinct Mfd-EC complexes in both ATP and ADP-bound states. The structures explain how Mfd is remodeled from its repressed conformation, how the UvrA-interacting surface of Mfd is hidden during most of the remodeling process to prevent premature engagement with the NER pathway, how Mfd alters the RNAP conformation to facilitate disassembly, and how Mfd forms a processive translocation complex after dislodging the RNAP. Our results reveal an elaborate mechanism for how Mfd kinetically discriminates paused from stalled ECs and disassembles stalled ECs to initiate TCR.

scholarly journals Single-molecule imaging reveals molecular coupling between transcription and DNA repair in live cells

2019 ◽  
Author(s):  
Han Ngoc Ho ◽  
Antoine van Oijen ◽  
Harshad Ghodke
Keyword(s):  
Rna Polymerase ◽  
Nucleotide Excision Repair ◽  
Single Molecule ◽  
Excision Repair ◽  
Model Organism ◽  
Coupling Factor ◽  
Live Cells ◽  
Nucleotide Excision ◽  
Transcription Coupled Repair

Actively transcribed genes are preferentially repaired in a conserved repair reaction known as transcription-coupled nucleotide excision repair1–3. During this reaction, stalled transcription elongation complexes at sites of lesions serve as a signal to trigger the assembly of nucleotide excision repair factors (reviewed in ref.4,5). In the model organism Escherichia coli, the transcription-repair coupling factor Mfd displaces the stalled RNA polymerase and hands-off the stall site to the nucleotide excision repair factors UvrAB for damage detection6–9. Despite in vitro evidence, it remains unclear how in live cells the stall site is faithfully handed over to UvrB from RNA polymerase and whether this handoff occurs via the Mfd-UvrA2-UvrB complex or via alternate reaction intermediates. Here, we visualise Mfd, the central player of transcription-coupled repair in actively growing cells and determine the catalytic requirements for faithful completion of the handoff during transcription-coupled repair. We find that the Mfd-UvrA2 complex is arrested on DNA in the absence of UvrB. Further, Mfd-UvrA2-UvrB complexes formed by UvrB mutants deficient in DNA loading and damage recognition, were also impaired in successful handoff. Our observations demonstrate that in live cells, the dissociation of Mfd is tightly coupled to successful loading of UvrB, providing a mechanism via which loading of UvrB occurs in a strand-specific manner during transcription-coupled repair.

scholarly journals Mechanistic insights in transcription-coupled nucleotide excision repair of ribosomal DNA

2018 ◽  
Vol 115 (29) ◽  
pp. E6770-E6779 ◽  
Author(s):  
Laurianne Daniel ◽  
Elena Cerutti ◽  
Lise-Marie Donnio ◽  
Julie Nonnekens ◽  
Christophe Carrat ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Nucleotide Excision Repair ◽  
Uv Irradiation ◽  
Ribosomal Dna ◽  
Excision Repair ◽  
Rna Polymerase I ◽  
Nucleotide Excision ◽  
Polymerase I ◽  
Uv Lesions ◽  
Transcription Coupled Repair

Nucleotide excision repair (NER) guarantees genome integrity against UV light-induced DNA damage. After UV irradiation, cells have to cope with a general transcriptional block. To ensure UV lesions repair specifically on transcribed genes, NER is coupled with transcription in an extremely organized pathway known as transcription-coupled repair. In highly metabolic cells, more than 60% of total cellular transcription results from RNA polymerase I activity. Repair of the mammalian transcribed ribosomal DNA has been scarcely studied. UV lesions severely block RNA polymerase I activity and the full transcription-coupled repair machinery corrects damage on actively transcribed ribosomal DNAs. After UV irradiation, RNA polymerase I is more bound to the ribosomal DNA and both are displaced to the nucleolar periphery. Importantly, the reentry of RNA polymerase I and the ribosomal DNA is dependent on the presence of UV lesions on DNA and independent of transcription restart.

scholarly journals Structural basis of TFIIH activation for nucleotide excision repair

2019 ◽  
Author(s):  
Goran Kokic ◽  
Aleksandar Chernev ◽  
Dimitry Tegunov ◽  
Christian Dienemann ◽  
Henning Urlaub ◽  
...  
Keyword(s):  
Dna Repair ◽  
Transcription Factor ◽  
Nucleotide Excision Repair ◽  
Excision Repair ◽  
Dna Lesions ◽  
Structural Basis ◽  
Disease Mutations ◽  
Mechanistic Analysis ◽  
Nucleotide Excision ◽  
Dna Complex

AbstractGenomes are constantly threatened by DNA damage, but cells can remove a large variety of DNA lesions by nucleotide excision repair (NER)1. Mutations in NER factors compromise cellular fitness and cause human diseases such as Xeroderma pigmentosum (XP), Cockayne syndrome and trichothiodystrophy2,3. The NER machinery is built around the multisubunit transcription factor IIH (TFIIH), which opens the DNA repair bubble, scans for the lesion, and coordinates excision of the damaged DNA single strand fragment1,4. TFIIH consists of a kinase module and a core module that contains the ATPases XPB and XPD5. Here we prepare recombinant human TFIIH and show that XPB and XPD are stimulated by the additional NER factors XPA and XPG, respectively. We then determine the cryo-electron microscopy structure of the human core TFIIH-XPA-DNA complex at 3.6 Å resolution. The structure represents the lesion-scanning intermediate on the NER pathway and rationalizes the distinct phenotypes of disease mutations. It reveals that XPB and XPD bind double- and single-stranded DNA, respectively, consistent with their translocase and helicase activities. XPA forms a bridge between XPB and XPD, and retains the DNA at the 5’-edge of the repair bubble. Biochemical data and comparisons with prior structures6,7 explain how XPA and XPG can switch TFIIH from a transcription factor to a DNA repair factor. During transcription, the kinase module inhibits the repair helicase XPD8. For DNA repair, XPA dramatically rearranges the core TFIIH structure, which reorients the ATPases, releases the kinase module and displaces a ‘plug’ element from the DNA-binding pore in XPD. This enables XPD to move by ~80 Å, engage with DNA, and scan for the lesion in a XPG-stimulated manner. Our results provide the basis for a detailed mechanistic analysis of the NER mechanism.

scholarly journals Structural basis of TFIIH activation for nucleotide excision repair

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Goran Kokic ◽  
Aleksandar Chernev ◽  
Dimitry Tegunov ◽  
Christian Dienemann ◽  
Henning Urlaub ◽  
...  
Keyword(s):  
Nucleotide Excision Repair ◽  
Excision Repair ◽  
Structural Basis ◽  
Nucleotide Excision

Nucleotide excision repair in the yeast Saccharomyces cerevisiae : its relationship to specialized mitotic recombination and RNA polymerase II basal transcription

1995 ◽  
Vol 347 (1319) ◽  
pp. 63-68 ◽  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Nucleotide Excision Repair ◽  
Excision Repair ◽  
Gene Products ◽  
Basal Transcription ◽  
Yeast Saccharomyces Cerevisiae ◽  
Nucleotide Excision ◽  
Yeast Genes

Nucleotide excision repair (ner) in eukaryotes is a biochemically complex process involving multiple gene products. The budding yeast Saccharomyces cerevisiae is an informative model for this process. Multiple genes and in some cases gene products that are indispensable for ner have been isolated from this organism. Homologues of many of these yeast genes are structurally and functionally conserved in higher organisms, including humans. The yeast Rad1/Rad10 heterodimeric protein complex is an endonuclease that is believed to participate in damage-specific incision of DNA during ner . This endonuclease is also required for specialized types of recombination. The products of the RAD3, SSL2(RAD25) SSL1 and TFB1 genes have dual roles in ner and in RNA polymerase II-dependent basal transcription.

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