1
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Fu I, Geacintov NE, Broyde S. Differing structures and dynamics of two photolesions portray verification differences by the human XPD helicase. Nucleic Acids Res 2023; 51:12261-12274. [PMID: 37933861 PMCID: PMC10711554 DOI: 10.1093/nar/gkad974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/28/2023] [Accepted: 10/16/2023] [Indexed: 11/08/2023] Open
Abstract
Ultraviolet light generates cyclobutane pyrimidine dimer (CPD) and pyrimidine 6-4 pyrimidone (6-4PP) photoproducts that cause skin malignancies if not repaired by nucleotide excision repair (NER). While the faster repair of the more distorting 6-4PPs is attributed mainly to more efficient recognition by XPC, the XPD lesion verification helicase may play a role, as it directly scans the damaged DNA strand. With extensive molecular dynamics simulations of XPD-bound single-strand DNA containing each lesion outside the entry pore of XPD, we elucidate strikingly different verification processes for these two lesions that have very different topologies. The open book-like CPD thymines are sterically blocked from pore entry and preferably entrapped by sensors that are outside the pore; however, the near-perpendicular 6-4PP thymines can enter, accompanied by a displacement of the Arch domain toward the lesion, which is thereby tightly accommodated within the pore. This trapped 6-4PP may inhibit XPD helicase activity to foster lesion verification by locking the Arch to other domains. Furthermore, the movement of the Arch domain, only in the case of 6-4PP, may trigger signaling to the XPG nuclease for subsequent lesion incision by fostering direct contact between the Arch domain and XPG, and thereby facilitating repair of 6-4PP.
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Affiliation(s)
- Iwen Fu
- Department of Biology, New York University, 24 Waverly Place, 6th Floor, New York, NY 10003, USA
| | - Nicholas E Geacintov
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY 10003, USA
| | - Suse Broyde
- Department of Biology, New York University, 24 Waverly Place, 6th Floor, New York, NY 10003, USA
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2
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He F, Bravo M, Fan L. Helicases required for nucleotide excision repair: structure, function and mechanism. Enzymes 2023; 54:273-304. [PMID: 37945175 DOI: 10.1016/bs.enz.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Nucleotide excision repair (NER) is a major DNA repair pathway conserved from bacteria to humans. Various DNA helicases, a group of enzymes capable of separating DNA duplex into two strands through ATP binding and hydrolysis, are required by NER to unwind the DNA duplex around the lesion to create a repair bubble and for damage verification and removal. In prokaryotes, UvrB helicase is required for repair bubble formation and damage verification, while UvrD helicase is responsible for the removal of the excised damage containing single-strand (ss) DNA fragment. In addition, UvrD facilitates transcription-coupled repair (TCR) by backtracking RNA polymerase stalled at the lesion. In eukaryotes, two helicases XPB and XPD from the transcription factor TFIIH complex fulfill the helicase requirements of NER. Interestingly, homologs of all these four helicases UvrB, UvrD, XPB, and XPD have been identified in archaea. This review summarizes our current understanding about the structure, function, and mechanism of these four helicases.
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Affiliation(s)
- Feng He
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, United States
| | - Marco Bravo
- Department of Biochemistry, University of California, Riverside, CA, United States
| | - Li Fan
- Department of Biochemistry, University of California, Riverside, CA, United States.
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3
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Compe E, Pangou E, Le May N, Elly C, Braun C, Hwang JH, Coin F, Sumara I, Choi KW, Egly JM. Phosphorylation of XPD drives its mitotic role independently of its DNA repair and transcription functions. SCIENCE ADVANCES 2022; 8:eabp9457. [PMID: 35977011 PMCID: PMC9385140 DOI: 10.1126/sciadv.abp9457] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
The helicase XPD is known as a key subunit of the DNA repair/transcription factor TFIIH. However, here, we report that XPD, independently to other TFIIH subunits, can localize with the motor kinesin Eg5 to mitotic spindles and the midbodies of human cells. The XPD/Eg5 partnership is promoted upon phosphorylation of Eg5/T926 by the kinase CDK1, and conversely, it is reduced once Eg5/S1033 is phosphorylated by NEK6, a mitotic kinase that also targets XPD at T425. The phosphorylation of XPD does not affect its DNA repair and transcription functions, but it is required for Eg5 localization, checkpoint activation, and chromosome segregation in mitosis. In XPD-mutated cells derived from a patient with xeroderma pigmentosum, the phosphomimetic form XPD/T425D or even the nonphosphorylatable form Eg5/S1033A specifically restores mitotic chromosome segregation errors. These results thus highlight the phospho-dependent mitotic function of XPD and reveal how mitotic defects might contribute to XPD-related disorders.
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Affiliation(s)
- Emmanuel Compe
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Expression et Réparation du Génome, Equipe labellisée Ligue contre le Cancer, CNRS/INSERM/Université de Strasbourg, BP 163, Illkirch Cedex, C. U., 67404 Strasbourg, France
| | - Evanthia Pangou
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Cycle Cellulaire et Signalisation de l’Ubiquitine, CNRS/INSERM/Université de Strasbourg, BP 163, Illkirch Cedex, C. U., 67404, Strasbourg, France
| | - Nicolas Le May
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Expression et Réparation du Génome, Equipe labellisée Ligue contre le Cancer, CNRS/INSERM/Université de Strasbourg, BP 163, Illkirch Cedex, C. U., 67404 Strasbourg, France
| | - Clémence Elly
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Expression et Réparation du Génome, Equipe labellisée Ligue contre le Cancer, CNRS/INSERM/Université de Strasbourg, BP 163, Illkirch Cedex, C. U., 67404 Strasbourg, France
| | - Cathy Braun
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Expression et Réparation du Génome, Equipe labellisée Ligue contre le Cancer, CNRS/INSERM/Université de Strasbourg, BP 163, Illkirch Cedex, C. U., 67404 Strasbourg, France
| | - Ji-Hyun Hwang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Frédéric Coin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Expression et Réparation du Génome, Equipe labellisée Ligue contre le Cancer, CNRS/INSERM/Université de Strasbourg, BP 163, Illkirch Cedex, C. U., 67404 Strasbourg, France
| | - Izabela Sumara
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Cycle Cellulaire et Signalisation de l’Ubiquitine, CNRS/INSERM/Université de Strasbourg, BP 163, Illkirch Cedex, C. U., 67404, Strasbourg, France
| | - Kwang-Wook Choi
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Jean-Marc Egly
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Expression et Réparation du Génome, Equipe labellisée Ligue contre le Cancer, CNRS/INSERM/Université de Strasbourg, BP 163, Illkirch Cedex, C. U., 67404 Strasbourg, France
- College of Medicine, National Taiwan Institute, Taipei 10051, Taiwan
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4
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Fu I, Mu H, Geacintov NE, Broyde S. Mechanism of lesion verification by the human XPD helicase in nucleotide excision repair. Nucleic Acids Res 2022; 50:6837-6853. [PMID: 35713557 PMCID: PMC9262607 DOI: 10.1093/nar/gkac496] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 05/11/2022] [Accepted: 05/25/2022] [Indexed: 01/19/2023] Open
Abstract
In nucleotide excision repair (NER), the xeroderma pigmentosum D helicase (XPD) scans DNA searching for bulky lesions, stalls when encountering such damage to verify its presence, and allows repair to proceed. Structural studies have shown XPD bound to its single-stranded DNA substrate, but molecular and dynamic characterization of how XPD translocates on undamaged DNA and how it stalls to verify lesions remains poorly understood. Here, we have performed extensive all-atom MD simulations of human XPD bound to undamaged and damaged ssDNA, containing a mutagenic pyrimidine (6-4) pyrimidone UV photoproduct (6-4PP), near the XPD pore entrance. We characterize how XPD responds to the presence of the DNA lesion, delineating the atomistic-scale mechanism that it utilizes to discriminate between damaged and undamaged nucleotides. We identify key amino acid residues, including FeS residues R112, R196, H135, K128, Arch residues E377 and R380, and ATPase lobe 1 residues 215-221, that are involved in damage verification and show how movements of Arch and ATPase lobe 1 domains relative to the FeS domain modulate these interactions. These structural and dynamic molecular depictions of XPD helicase activity with unmodified DNA and its inhibition by the lesion elucidate how the lesion is verified by inducing XPD stalling.
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Affiliation(s)
- Iwen Fu
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
| | - Hong Mu
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
| | - Nicholas E Geacintov
- Department of Chemistry, New York University, 100 Washington Square East, New York, NY 10003, USA
| | - Suse Broyde
- To whom correspondence should be addressed. Tel: +1 212 998 8231;
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5
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Naumenko NV, Petruseva IO, Lomzov AA, Lavrik OI. Recognition and removal of clustered DNA lesions via nucleotide excision repair. DNA Repair (Amst) 2021; 108:103225. [PMID: 34562718 DOI: 10.1016/j.dnarep.2021.103225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 06/25/2021] [Accepted: 09/05/2021] [Indexed: 10/20/2022]
Abstract
Clustered damage of DNA consists of two or more lesions located within one or two turns of the DNA helix. Clusters consisting of lesions of various structures can arise under the influence of strong damaging factors, especially if the cells have a compromised repair status. In this work, we analyzed how the presence of an analog of the apurinic/apyrimidinic site - a non-nucleoside residue consisting of diethylene glycol phosphodiester (DEG) - affects the recognition and removal of a bulky lesion (a non-nucleoside site of the modified DNA strand containing a fluorescein residue, nFlu) from DNA by a mammalian nucleotide excision repair system. Here we demonstrated that the efficiency of nFlu removal decreases in the presence of DEG in the complementary strand and is completely suppressed when the DEG is located opposite the nFlu. By contrast, protein factor XPC-RAD23B, which initiates global genomic nucleotide excision repair, has higher affinity for DNA containing clustered damage as compared to DNA containing a single bulky lesion; the affinity of XPC strengthens as the positions of DEG and nFlu become closer. The changes in the double-stranded DNA's geometry caused by the presence of clustered damage were also assessed. The obtained experimental data together with the results of molecular dynamics simulations make it possible to get insight into the structural features of DNA containing clustered lesions that determine the efficiency of repair. Speaking more broadly, this study should help to understand the probable fate of bulky adduct-containing clusters of various topologies in the mammalian cell.
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Affiliation(s)
- N V Naumenko
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - I O Petruseva
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
| | - A A Lomzov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
| | - O I Lavrik
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia.
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6
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van Eeuwen T, Shim Y, Kim HJ, Zhao T, Basu S, Garcia BA, Kaplan CD, Min JH, Murakami K. Cryo-EM structure of TFIIH/Rad4-Rad23-Rad33 in damaged DNA opening in nucleotide excision repair. Nat Commun 2021; 12:3338. [PMID: 34099686 PMCID: PMC8184850 DOI: 10.1038/s41467-021-23684-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 05/05/2021] [Indexed: 11/08/2022] Open
Abstract
The versatile nucleotide excision repair (NER) pathway initiates as the XPC-RAD23B-CETN2 complex first recognizes DNA lesions from the genomic DNA and recruits the general transcription factor complex, TFIIH, for subsequent lesion verification. Here, we present a cryo-EM structure of an NER initiation complex containing Rad4-Rad23-Rad33 (yeast homologue of XPC-RAD23B-CETN2) and 7-subunit coreTFIIH assembled on a carcinogen-DNA adduct lesion at 3.9-9.2 Å resolution. A ~30-bp DNA duplex could be mapped as it straddles between Rad4 and the Ssl2 (XPB) subunit of TFIIH on the 3' and 5' side of the lesion, respectively. The simultaneous binding with Rad4 and TFIIH was permitted by an unwinding of DNA at the lesion. Translocation coupled with torque generation by Ssl2 and Rad4 would extend the DNA unwinding at the lesion and deliver the damaged strand to Rad3 (XPD) in an open form suitable for subsequent lesion scanning and verification.
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Affiliation(s)
- Trevor van Eeuwen
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Center for Genome Integrity, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Yoonjung Shim
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA
| | - Hee Jong Kim
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Center for Genome Integrity, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Tingting Zhao
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Shrabani Basu
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Benjamin A Garcia
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jung-Hyun Min
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA.
| | - Kenji Murakami
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Penn Center for Genome Integrity, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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7
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Petruseva I, Naumenko N, Kuper J, Anarbaev R, Kappenberger J, Kisker C, Lavrik O. The Interaction Efficiency of XPD-p44 With Bulky DNA Damages Depends on the Structure of the Damage. Front Cell Dev Biol 2021; 9:617160. [PMID: 33777931 PMCID: PMC7991749 DOI: 10.3389/fcell.2021.617160] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 02/22/2021] [Indexed: 11/28/2022] Open
Abstract
The successful elimination of bulky DNA damages via the nucleotide excision repair (NER) system is largely determined by the damage recognition step. This step consists of primary recognition and verification of the damage. The TFIIH helicase XPD plays a key role in the verification step during NER. To date, the mechanism of damage verification is not sufficiently understood and requires further detailed research. This study is a systematic investigation of the interaction of ctXPD (Chaetomium thermophilum) as well as ctXPD-ctp44 with model DNAs, which contain structurally different bulky lesions with previously estimated NER repair efficiencies. We have used ATPase and DNA binding studies to assess the interaction of ctXPD with damaged DNA. The result of the analysis of ctXPD-ctp44 binding to DNA containing fluorescent and photoactivatable lesions demonstrates the relationship between the affinity of XPD for DNAs containing bulky damages and the ability of the NER system to eliminate the damage. Photo-cross-linking of ctXPD with DNA probes containing repairable and unrepairable photoactivatable damages reveals differences in the DNA interaction efficiency in the presence and absence of ctp44. In general, the results obtained indicate the ability of ctXPD-ctp44 to interact with a damage and suggest a significant role for ctp44 subunit in the verification process.
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Affiliation(s)
- Irina Petruseva
- Laboratory of Bioorganic Chemistry of Enzymes, Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
| | - Natalia Naumenko
- Laboratory of Bioorganic Chemistry of Enzymes, Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
| | - Jochen Kuper
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Wuerzburg, Wuerzburg, Germany
| | - Rashid Anarbaev
- Laboratory of Bioorganic Chemistry of Enzymes, Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
| | - Jeannette Kappenberger
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Wuerzburg, Wuerzburg, Germany
| | - Caroline Kisker
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Wuerzburg, Wuerzburg, Germany
| | - Olga Lavrik
- Laboratory of Bioorganic Chemistry of Enzymes, Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
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8
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Barnett JT, Kuper J, Koelmel W, Kisker C, Kad NM. The TFIIH subunits p44/p62 act as a damage sensor during nucleotide excision repair. Nucleic Acids Res 2021; 48:12689-12696. [PMID: 33166411 PMCID: PMC7736792 DOI: 10.1093/nar/gkaa973] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 09/17/2020] [Accepted: 10/13/2020] [Indexed: 01/09/2023] Open
Abstract
Nucleotide excision repair (NER) in eukaryotes is orchestrated by the core form of the general transcription factor TFIIH, containing the helicases XPB, XPD and five ‘structural’ subunits, p62, p44, p34, p52 and p8. Recent cryo-EM structures show that p62 makes extensive contacts with p44 and in part occupies XPD’s DNA binding site. While p44 is known to regulate the helicase activity of XPD during NER, p62 is thought to be purely structural. Here, using helicase and adenosine triphosphatase assays we show that a complex containing p44 and p62 enhances XPD’s affinity for dsDNA 3-fold over p44 alone. Remarkably, the relative affinity is further increased to 60-fold by dsDNA damage. Direct binding studies show this preference derives from p44/p62’s high affinity (20 nM) for damaged ssDNA. Single molecule imaging of p44/p62 complexes without XPD reveals they bind to and randomly diffuse on DNA, however, in the presence of UV-induced DNA lesions these complexes stall. Combined with the analysis of a recent cryo-EM structure, we suggest that p44/p62 acts as a novel DNA-binding entity that enhances damage recognition in TFIIH. This revises our understanding of TFIIH and prompts investigation into the core subunits for an active role during DNA repair and/or transcription.
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Affiliation(s)
- Jamie T Barnett
- School of Biological Sciences, University of Kent, Canterbury CT2 7NH, UK
| | - Jochen Kuper
- Rudolf Virchow Center for Integrative and Translational Bioimaging, Institute for Structural Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Wolfgang Koelmel
- Rudolf Virchow Center for Integrative and Translational Bioimaging, Institute for Structural Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Caroline Kisker
- Rudolf Virchow Center for Integrative and Translational Bioimaging, Institute for Structural Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Neil M Kad
- School of Biological Sciences, University of Kent, Canterbury CT2 7NH, UK
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9
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Envisioning how the prototypic molecular machine TFIIH functions in transcription initiation and DNA repair. DNA Repair (Amst) 2020; 96:102972. [PMID: 33007515 DOI: 10.1016/j.dnarep.2020.102972] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/02/2020] [Accepted: 09/07/2020] [Indexed: 12/22/2022]
Abstract
Critical for transcription initiation and bulky lesion DNA repair, TFIIH provides an exemplary system to connect molecular mechanisms to biological outcomes due to its strong genetic links to different specific human diseases. Recent advances in structural and computational biology provide a unique opportunity to re-examine biologically relevant molecular structures and develop possible mechanistic insights for the large dynamic TFIIH complex. TFIIH presents many puzzles involving how its two SF2 helicase family enzymes, XPB and XPD, function in transcription initiation and repair: how do they initiate transcription, detect and verify DNA damage, select the damaged strand for incision, coordinate repair with transcription and cell cycle through Cdk-activating-kinase (CAK) signaling, and result in very different specific human diseases associated with cancer, aging, and development from single missense mutations? By joining analyses of breakthrough cryo-electron microscopy (cryo-EM) structures and advanced computation with data from biochemistry and human genetics, we develop unified concepts and molecular level understanding for TFIIH functions with a focus on structural mechanisms. We provocatively consider that TFIIH may have first evolved from evolutionary pressure for TCR to resolve arrested transcription blocks to DNA replication and later added its key roles in transcription initiation and global DNA repair. We anticipate that this level of mechanistic information will have significant impact on thinking about TFIIH, laying a robust foundation suitable to develop new paradigms for DNA transcription initiation and repair along with insights into disease prevention, susceptibility, diagnosis and interventions.
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10
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Onwubiko NO, Borst A, Diaz SA, Passkowski K, Scheffel F, Tessmer I, Nasheuer HP. SV40 T antigen interactions with ssDNA and replication protein A: a regulatory role of T antigen monomers in lagging strand DNA replication. Nucleic Acids Res 2020; 48:3657-3677. [PMID: 32128579 PMCID: PMC7144908 DOI: 10.1093/nar/gkaa138] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/14/2020] [Accepted: 02/26/2020] [Indexed: 01/08/2023] Open
Abstract
DNA replication is a central process in all living organisms. Polyomavirus DNA replication serves as a model system for eukaryotic DNA replication and has considerably contributed to our understanding of basic replication mechanisms. However, the details of the involved processes are still unclear, in particular regarding lagging strand synthesis. To delineate the complex mechanism of coordination of various cellular proteins binding simultaneously or consecutively to DNA to initiate replication, we investigated single-stranded DNA (ssDNA) interactions by the SV40 large T antigen (Tag). Using single molecule imaging by atomic force microscopy (AFM) combined with biochemical and spectroscopic analyses we reveal independent activity of monomeric and oligomeric Tag in high affinity binding to ssDNA. Depending on ssDNA length, we obtain dissociation constants for Tag-ssDNA interactions (KD values of 10–30 nM) that are in the same order of magnitude as ssDNA binding by human replication protein A (RPA). Furthermore, we observe the formation of RPA-Tag-ssDNA complexes containing hexameric as well as monomeric Tag forms. Importantly, our data clearly show stimulation of primase function in lagging strand Okazaki fragment synthesis by monomeric Tag whereas hexameric Tag inhibits the reaction, redefining DNA replication initiation on the lagging strand.
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Affiliation(s)
- Nichodemus O Onwubiko
- Biochemistry, School of Natural Sciences, Center for Chromosome Biology, Biomedical SciencesBuilding, NUI Galway, New Castle Road, Galway, Ireland
| | - Angela Borst
- Rudolf Virchow Center for Experimental Biomedicine, University ofWürzburg, Josef Schneider Strasse 2, 97080 Würzburg, Germany
| | - Suraya A Diaz
- Biochemistry, School of Natural Sciences, Center for Chromosome Biology, Biomedical SciencesBuilding, NUI Galway, New Castle Road, Galway, Ireland
| | - Katharina Passkowski
- Rudolf Virchow Center for Experimental Biomedicine, University ofWürzburg, Josef Schneider Strasse 2, 97080 Würzburg, Germany
| | - Felicia Scheffel
- Rudolf Virchow Center for Experimental Biomedicine, University ofWürzburg, Josef Schneider Strasse 2, 97080 Würzburg, Germany
| | - Ingrid Tessmer
- Rudolf Virchow Center for Experimental Biomedicine, University ofWürzburg, Josef Schneider Strasse 2, 97080 Würzburg, Germany
| | - Heinz P Nasheuer
- Biochemistry, School of Natural Sciences, Center for Chromosome Biology, Biomedical SciencesBuilding, NUI Galway, New Castle Road, Galway, Ireland
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11
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Greber BJ, Toso DB, Fang J, Nogales E. The complete structure of the human TFIIH core complex. eLife 2019; 8:e44771. [PMID: 30860024 PMCID: PMC6422496 DOI: 10.7554/elife.44771] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/03/2019] [Indexed: 01/26/2023] Open
Abstract
Transcription factor IIH (TFIIH) is a heterodecameric protein complex critical for transcription initiation by RNA polymerase II and nucleotide excision DNA repair. The TFIIH core complex is sufficient for its repair functions and harbors the XPB and XPD DNA-dependent ATPase/helicase subunits, which are affected by human disease mutations. Transcription initiation additionally requires the CdK activating kinase subcomplex. Previous structural work has provided only partial insight into the architecture of TFIIH and its interactions within transcription pre-initiation complexes. Here, we present the complete structure of the human TFIIH core complex, determined by phase-plate cryo-electron microscopy at 3.7 Å resolution. The structure uncovers the molecular basis of TFIIH assembly, revealing how the recruitment of XPB by p52 depends on a pseudo-symmetric dimer of homologous domains in these two proteins. The structure also suggests a function for p62 in the regulation of XPD, and allows the mapping of previously unresolved human disease mutations.
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Affiliation(s)
- Basil J Greber
- California Institute for Quantitative BiosciencesUniversity of CaliforniaBerkeleyUnited States
- Molecular Biophysics and Integrative Bio-Imaging DivisionLawrence Berkeley National LaboratoryBerkeleyUnited States
| | - Daniel B Toso
- California Institute for Quantitative BiosciencesUniversity of CaliforniaBerkeleyUnited States
| | - Jie Fang
- Howard Hughes Medical Institute, University of CaliforniaBerkeleyUnited States
| | - Eva Nogales
- California Institute for Quantitative BiosciencesUniversity of CaliforniaBerkeleyUnited States
- Molecular Biophysics and Integrative Bio-Imaging DivisionLawrence Berkeley National LaboratoryBerkeleyUnited States
- Howard Hughes Medical Institute, University of CaliforniaBerkeleyUnited States
- Department of Molecular and Cell BiologyUniversity of CaliforniaBerkeleyUnited States
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12
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Kolesnikova O, Radu L, Poterszman A. TFIIH: A multi-subunit complex at the cross-roads of transcription and DNA repair. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2019; 115:21-67. [PMID: 30798933 DOI: 10.1016/bs.apcsb.2019.01.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Transcription factor IIH (TFIIH) is a multiprotein complex involved in both eukaryotic transcription and DNA repair, revealing a tight connection between these two processes. Composed of 10 subunits, it can be resolved into a 7-subunits core complex with the XPB translocase and the XPD helicase, and the 3-subunits kinase complex CAK, which also exists as a free complex with a distinct function. Initially identified as basal transcription factor, TFIIH also participates in transcription regulation and plays a key role in nucleotide excision repair (NER) for opening DNA at damaged sites, lesion verification and recruitment of additional repair factors. Our understanding of TFIIH function in eukaryotic cells has greatly benefited from studies of the genetic rare diseases xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD), that are not only characterized by cancer and aging predispositions but also by neurological and developmental defects. Although much remains unknown about TFIIH function, significant progresses have been done regarding the structure of the complex, the functions of its catalytic subunits and the multiple roles of the regulatory core-TFIIH subunits. This review provides a non-exhaustive survey of key discoveries on the structure and function of this pivotal factor, which can be considered as a promising target for therapeutic strategies.
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Affiliation(s)
- Olga Kolesnikova
- Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch, France; Université de Strasbourg, Illkirch, France
| | - Laura Radu
- Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch, France; Université de Strasbourg, Illkirch, France
| | - Arnaud Poterszman
- Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch, France; Université de Strasbourg, Illkirch, France.
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13
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Greber BJ, Nogales E. The Structures of Eukaryotic Transcription Pre-initiation Complexes and Their Functional Implications. Subcell Biochem 2019; 93:143-192. [PMID: 31939151 DOI: 10.1007/978-3-030-28151-9_5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transcription is a highly regulated process that supplies living cells with coding and non-coding RNA molecules. Failure to properly regulate transcription is associated with human pathologies, including cancers. RNA polymerase II is the enzyme complex that synthesizes messenger RNAs that are then translated into proteins. In spite of its complexity, RNA polymerase requires a plethora of general transcription factors to be recruited to the transcription start site as part of a large transcription pre-initiation complex, and to help it gain access to the transcribed strand of the DNA. This chapter reviews the structure and function of these eukaryotic transcription pre-initiation complexes, with a particular emphasis on two of its constituents, the multisubunit complexes TFIID and TFIIH. We also compare the overall architecture of the RNA polymerase II pre-initiation complex with those of RNA polymerases I and III, involved in transcription of ribosomal RNA and non-coding RNAs such as tRNAs and snRNAs, and discuss the general, conserved features that are applicable to all eukaryotic RNA polymerase systems.
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Affiliation(s)
- Basil J Greber
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, 94720, USA.
- Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Eva Nogales
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA, 94720, USA
- Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
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14
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White MF, Allers T. DNA repair in the archaea-an emerging picture. FEMS Microbiol Rev 2018; 42:514-526. [PMID: 29741625 DOI: 10.1093/femsre/fuy020] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/02/2018] [Indexed: 12/12/2022] Open
Abstract
There has long been a fascination in the DNA repair pathways of archaea, for two main reasons. Firstly, many archaea inhabit extreme environments where the rate of physical damage to DNA is accelerated. These archaea might reasonably be expected to have particularly robust or novel DNA repair pathways to cope with this. Secondly, the archaea have long been understood to be a lineage distinct from the bacteria, and to share a close relationship with the eukarya, particularly in their information processing systems. Recent discoveries suggest the eukarya arose from within the archaeal domain, and in particular from lineages related to the TACK superphylum and Lokiarchaea. Thus, archaeal DNA repair proteins and pathways can represent a useful model system. This review focuses on recent advances in our understanding of archaeal DNA repair processes including base excision repair, nucleotide excision repair, mismatch repair and double-strand break repair. These advances are discussed in the context of the emerging picture of the evolution and relationship of the three domains of life.
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Affiliation(s)
- Malcolm F White
- Biomedical Sciences Research Complex, School of Biology, University of St Andrews, Fife KY16 9ST, UK
| | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK
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15
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Mohan Bangalore D, Tessmer I. Unique insight into protein-DNA interactions from single molecule atomic force microscopy. AIMS BIOPHYSICS 2018. [DOI: 10.3934/biophy.2018.3.194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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16
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RecQ and Fe-S helicases have unique roles in DNA metabolism dictated by their unwinding directionality, substrate specificity, and protein interactions. Biochem Soc Trans 2017; 46:77-95. [PMID: 29273621 DOI: 10.1042/bst20170044] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/15/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022]
Abstract
Helicases are molecular motors that play central roles in nucleic acid metabolism. Mutations in genes encoding DNA helicases of the RecQ and iron-sulfur (Fe-S) helicase families are linked to hereditary disorders characterized by chromosomal instabilities, highlighting the importance of these enzymes. Moreover, mono-allelic RecQ and Fe-S helicase mutations are associated with a broad spectrum of cancers. This review will discuss and contrast the specialized molecular functions and biological roles of RecQ and Fe-S helicases in DNA repair, the replication stress response, and the regulation of gene expression, laying a foundation for continued research in these important areas of study.
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17
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Beckwitt EC, Kong M, Van Houten B. Studying protein-DNA interactions using atomic force microscopy. Semin Cell Dev Biol 2017; 73:220-230. [PMID: 28673677 DOI: 10.1016/j.semcdb.2017.06.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/27/2017] [Accepted: 06/29/2017] [Indexed: 12/12/2022]
Abstract
Atomic force microscopy (AFM) has made significant contributions to the study of protein-DNA interactions by making it possible to topographically image biological samples. A single protein-DNA binding reaction imaged by AFM can reveal protein binding specificity and affinity, protein-induced DNA bending, and protein binding stoichiometry. Changes in DNA structure, complex conformation, and cooperativity, can also be analyzed. In this review we highlight some important examples in the literature and discuss the advantages and limitations of these measurements. We also discuss important advances in technology that will facilitate the progress of AFM in the future.
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Affiliation(s)
- Emily C Beckwitt
- Program in Molecular Biophysics and Structural Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA; The University of Pittsburgh Cancer Institute, Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Muwen Kong
- Program in Molecular Biophysics and Structural Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA; The University of Pittsburgh Cancer Institute, Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Bennett Van Houten
- Program in Molecular Biophysics and Structural Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA; The University of Pittsburgh Cancer Institute, Hillman Cancer Center, Pittsburgh, PA 15213, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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18
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Crouch JD, Brosh RM. Mechanistic and biological considerations of oxidatively damaged DNA for helicase-dependent pathways of nucleic acid metabolism. Free Radic Biol Med 2017; 107:245-257. [PMID: 27884703 PMCID: PMC5440220 DOI: 10.1016/j.freeradbiomed.2016.11.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 11/11/2016] [Accepted: 11/13/2016] [Indexed: 12/21/2022]
Abstract
Cells are under constant assault from reactive oxygen species that occur endogenously or arise from environmental agents. An important consequence of such stress is the generation of oxidatively damaged DNA, which is represented by a wide range of non-helix distorting and helix-distorting bulkier lesions that potentially affect a number of pathways including replication and transcription; consequently DNA damage tolerance and repair pathways are elicited to help cells cope with the lesions. The cellular consequences and metabolism of oxidatively damaged DNA can be quite complex with a number of DNA metabolic proteins and pathways involved. Many of the responses to oxidative stress involve a specialized class of enzymes known as helicases, the topic of this review. Helicases are molecular motors that convert the energy of nucleoside triphosphate hydrolysis to unwinding of structured polynucleic acids. Helicases by their very nature play fundamentally important roles in DNA metabolism and are implicated in processes that suppress chromosomal instability, genetic disease, cancer, and aging. We will discuss the roles of helicases in response to nuclear and mitochondrial oxidative stress and how this important class of enzymes help cells cope with oxidatively generated DNA damage through their functions in the replication stress response, DNA repair, and transcriptional regulation.
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Affiliation(s)
- Jack D Crouch
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA.
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19
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Gross J, Wirth N, Tessmer I. Atomic Force Microscopy Investigations of DNA Lesion Recognition in Nucleotide Excision Repair. J Vis Exp 2017:55501. [PMID: 28570512 PMCID: PMC5608143 DOI: 10.3791/55501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Abstract
AFM imaging is a powerful technique for the study of protein-DNA interactions. This single molecule method allows the simultaneous resolution of different molecules and molecular assemblies in a heterogeneous sample. In the particular context of DNA interacting protein systems, different protein complex forms and their corresponding binding positions on target sites containing DNA fragments can thus be distinguished. Here, an application of AFM to the study of DNA lesion recognition in the prokaryotic and eukaryotic nucleotide excision DNA repair (NER) systems is presented. The procedures of DNA and protein sample preparations are described and experimental as well as analytical details of the experiments are provided. The data allow important conclusions on the strategies by which target site verification may be achieved by the NER proteins. Interestingly, they indicate different approaches of lesion recognition and identification for the eukaryotic NER system, depending on the type of lesion. Furthermore, distinct structural properties of the two different helicases involved in prokaryotic and eukaryotic NER result in and explain the different strategies observed for these two systems. Importantly, these experimental and analytical approaches can be applied not only to the study of DNA repair but also very similarly to other DNA interacting protein systems such as those involved in replication or transcription processes.
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Affiliation(s)
- Jonas Gross
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg
| | - Nicolas Wirth
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg
| | - Ingrid Tessmer
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg;
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20
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The excluded DNA strand is SEW important for hexameric helicase unwinding. Methods 2016; 108:79-91. [DOI: 10.1016/j.ymeth.2016.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/07/2016] [Accepted: 04/07/2016] [Indexed: 02/04/2023] Open
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21
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López-Valverde G, Garcia-Martin E, Fernández-Mateos J, Cruz-González F, Larrosa-Povés JM, Polo-Llorens V, Pablo-Júlvez LE, González-Sarmiento R. Study of association between pre-senile cataracts and rs11615 of ERCC1, rs13181 of ERCC2, and rs25487 of XRCC1 polymorphisms in a Spanish population. Ophthalmic Genet 2016; 38:314-319. [DOI: 10.1080/13816810.2016.1217548] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Gloria López-Valverde
- Department of Ophthalmology, University Hospital of Salamanca, Salamanca, Spain
- Department of Ophthalmology, Royo Villanova Hospital, Zaragoza, Spain
- Department of Ophthalmology, Miguel Servet University Hospital, Zaragoza, Spain
| | - Elena Garcia-Martin
- Department of Ophthalmology, Miguel Servet University Hospital, Zaragoza, Spain
- Department of Ophthalmology, Instituto de Investigaciones Sanitarias de Aragón (IIS Aragon), Zaragoza, Spain
| | - Javier Fernández-Mateos
- Molecular Medicine Unit, Department of Medicine, Institute of Molecular and Cellular Biology of Cancer and Institute of Biomedical Research of Salamanca, University of Salamanca-University Hospital of Salamanca CSIC, Salamanca, Spain
| | | | - José M. Larrosa-Povés
- Department of Ophthalmology, Miguel Servet University Hospital, Zaragoza, Spain
- Department of Ophthalmology, Instituto de Investigaciones Sanitarias de Aragón (IIS Aragon), Zaragoza, Spain
| | - Vicente Polo-Llorens
- Department of Ophthalmology, Miguel Servet University Hospital, Zaragoza, Spain
- Department of Ophthalmology, Instituto de Investigaciones Sanitarias de Aragón (IIS Aragon), Zaragoza, Spain
| | - Luis E. Pablo-Júlvez
- Department of Ophthalmology, Miguel Servet University Hospital, Zaragoza, Spain
- Department of Ophthalmology, Instituto de Investigaciones Sanitarias de Aragón (IIS Aragon), Zaragoza, Spain
| | - Rogelio González-Sarmiento
- Molecular Medicine Unit, Department of Medicine, Institute of Molecular and Cellular Biology of Cancer and Institute of Biomedical Research of Salamanca, University of Salamanca-University Hospital of Salamanca CSIC, Salamanca, Spain
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22
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Wirth N, Gross J, Roth HM, Buechner CN, Kisker C, Tessmer I. Conservation and Divergence in Nucleotide Excision Repair Lesion Recognition. J Biol Chem 2016; 291:18932-46. [PMID: 27405761 DOI: 10.1074/jbc.m116.739425] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Indexed: 11/06/2022] Open
Abstract
Nucleotide excision repair is an important and highly conserved DNA repair mechanism with an exceptionally large range of chemically and structurally unrelated targets. Lesion verification is believed to be achieved by the helicases UvrB and XPD in the prokaryotic and eukaryotic processes, respectively. Using single molecule atomic force microscopy analyses, we demonstrate that UvrB and XPD are able to load onto DNA and pursue lesion verification in the absence of the initial lesion detection proteins. Interestingly, our studies show different lesion recognition strategies for the two functionally homologous helicases, as apparent from their distinct DNA strand preferences, which can be rationalized from the different structural features and interactions with other nucleotide excision repair protein factors of the two enzymes.
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Affiliation(s)
- Nicolas Wirth
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Jonas Gross
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Heide M Roth
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Claudia N Buechner
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Caroline Kisker
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
| | - Ingrid Tessmer
- From the Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
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23
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Sugasawa K. Molecular mechanisms of DNA damage recognition for mammalian nucleotide excision repair. DNA Repair (Amst) 2016; 44:110-117. [PMID: 27264556 DOI: 10.1016/j.dnarep.2016.05.015] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
For faithful DNA repair, it is crucial for cells to locate lesions precisely within the vast genome. In the mammalian global genomic nucleotide excision repair (NER) pathway, this difficult task is accomplished through multiple steps, in which the xeroderma pigmentosum group C (XPC) protein complex plays a central role. XPC senses the presence of oscillating 'normal' bases in the DNA duplex, and its binding properties contribute to the extremely broad substrate specificity of NER. Unlike XPC, which acts as a versatile sensor of DNA helical distortion, the UV-damaged DNA-binding protein (UV-DDB) is more specialized, recognizing UV-induced photolesions and facilitating recruitment of XPC. Recent single-molecule analyses and structural studies have advanced our understanding of how UV-DDB finds its targets, particularly in the context of chromatin. After XPC binds DNA, it is necessary to verify the presence of damage in order to avoid potentially deleterious incisions at damage-free sites. Accumulating evidence suggests that XPA and the helicase activity of transcription factor IIH (TFIIH) cooperate to verify abnormalities in DNA chemistry. This chapter reviews recent findings about the mechanisms underlying the efficiency, versatility, and accuracy of NER.
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Affiliation(s)
- Kaoru Sugasawa
- Biosignal Research Center, Kobe University, Kobe, Hyogo 657-8501, Japan.
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24
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Abstract
XPD, as part of the TFIIH complex, has classically been linked to the damage verification step of nucleotide excision repair (NER). However, recent data indicate that XPD, due to its iron-sulfur center interacts with the iron sulfur cluster assembly proteins, and may interact with other proteins in the cell to mediate a diverse set of biological functions including cell cycle regulation, mitosis, and mitochondrial function. In this perspective, after first reviewing the function and some of the key disease causing variants that affect XPD's interaction with TFIIH and the CDK-activating kinase complex (CAK), we investigate these intriguing cellular roles of XPD and highlight important unanswered questions that provide a fertile ground for further scientific exploration.
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Affiliation(s)
- Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, United States.
| | - Jochen Kuper
- Rudolf-Virchow-Center for Experimental Biomedicine, University of Wuerzburg, Wuerzburg, Germany.
| | - Caroline Kisker
- Rudolf-Virchow-Center for Experimental Biomedicine, University of Wuerzburg, Wuerzburg, Germany.
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25
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Abstract
Cold-sensitive phenotypes have helped us understand macromolecular assembly and biological phenomena, yet few attempts have been made to understand the basis of cold sensitivity or to elicit it by design. We report a method for rational design of cold-sensitive phenotypes. The method involves generation of partial loss-of-function mutants, at either buried or functional sites, coupled with selective overexpression strategies. The only essential input is amino acid sequence, although available structural information can be used as well. The method has been used to elicit cold-sensitive mutants of a variety of proteins, both monomeric and dimeric, and in multiple organisms, namely Escherichia coli, Saccharomyces cerevisiae, and Drosophila melanogaster This simple, yet effective technique of inducing cold sensitivity eliminates the need for complex mutations and provides a plausible molecular mechanism for eliciting cold-sensitive phenotypes.
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26
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Constantinescu-Aruxandei D, Petrovic-Stojanovska B, Penedo JC, White MF, Naismith JH. Mechanism of DNA loading by the DNA repair helicase XPD. Nucleic Acids Res 2016; 44:2806-15. [PMID: 26896802 PMCID: PMC4824113 DOI: 10.1093/nar/gkw102] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 02/09/2016] [Indexed: 01/14/2023] Open
Abstract
The xeroderma pigmentosum group D (XPD) helicase is a component of the transcription factor IIH complex in eukaryotes and plays an essential role in DNA repair in the nucleotide excision repair pathway. XPD is a 5′ to 3′ helicase with an essential iron–sulfur cluster. Structural and biochemical studies of the monomeric archaeal XPD homologues have aided a mechanistic understanding of this important class of helicase, but several important questions remain open. In particular, the mechanism for DNA loading, which is assumed to require large protein conformational change, is not fully understood. Here, DNA binding by the archaeal XPD helicase from Thermoplasma acidophilum has been investigated using a combination of crystallography, cross-linking, modified substrates and biochemical assays. The data are consistent with an initial tight binding of ssDNA to helicase domain 2, followed by transient opening of the interface between the Arch and 4FeS domains, allowing access to a second binding site on helicase domain 1 that directs DNA through the pore. A crystal structure of XPD from Sulfolobus acidocaldiarius that lacks helicase domain 2 has an otherwise unperturbed structure, emphasizing the stability of the interface between the Arch and 4FeS domains in XPD.
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Affiliation(s)
| | | | - J Carlos Penedo
- Biomedical Sciences Research Complex, University of St Andrews, Fife KY16 9ST, UK
| | - Malcolm F White
- Biomedical Sciences Research Complex, University of St Andrews, Fife KY16 9ST, UK
| | - James H Naismith
- Biomedical Sciences Research Complex, University of St Andrews, Fife KY16 9ST, UK
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27
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Abstract
Nucleotide excision repair (NER) is a highly versatile and efficient DNA repair process, which is responsible for the removal of a large number of structurally diverse DNA lesions. Its extreme broad substrate specificity ranges from DNA damages formed upon exposure to ultraviolet radiation to numerous bulky DNA adducts induced by mutagenic environmental chemicals and cytotoxic drugs used in chemotherapy. Defective NER leads to serious diseases, such as xeroderma pigmentosum (XP). Eight XP complementation groups are known of which seven (XPA-XPG) are caused by mutations in genes involved in the NER process. The eighth gene, XPV, codes for the DNA polymerase ɳ, which replicates through DNA lesions in a process called translesion synthesis (TLS). Over the past decade, detailed structural information of these DNA repair proteins involved in eukaryotic NER and TLS have emerged. These structures allow us now to understand the molecular mechanism of the NER and TLS processes in quite some detail and we have begun to understand the broad substrate specificity of NER. In this review, we aim to highlight recent advances in the process of damage recognition and repair as well as damage tolerance by the XP proteins.
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28
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Abstract
Hexameric helicases control both the initiation and the elongation phase of DNA replication. The toroidal structure of these enzymes provides an inherent challenge in the opening and loading onto DNA at origins, as well as the conformational changes required to exclude one strand from the central channel and activate DNA unwinding. Recently, high-resolution structures have not only revealed the architecture of various hexameric helicases but also detailed the interactions of DNA within the central channel, as well as conformational changes that occur during loading. This structural information coupled with advanced biochemical reconstitutions and biophysical methods have transformed our understanding of the dynamics of both the helicase structure and the DNA interactions required for efficient unwinding at the replisome.
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Affiliation(s)
- Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798, USA
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29
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Tripartite DNA Lesion Recognition and Verification by XPC, TFIIH, and XPA in Nucleotide Excision Repair. Mol Cell 2015; 59:1025-34. [PMID: 26384665 DOI: 10.1016/j.molcel.2015.08.012] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 07/09/2015] [Accepted: 08/17/2015] [Indexed: 11/23/2022]
Abstract
Transcription factor IIH (TFIIH) is essential for both transcription and nucleotide excision repair (NER). DNA lesions are initially detected by NER factors XPC and XPE or stalled RNA polymerases, but only bulky lesions are preferentially repaired by NER. To elucidate substrate specificity in NER, we have prepared homogeneous human ten-subunit TFIIH and its seven-subunit core (Core7) without the CAK module and show that bulky lesions in DNA inhibit the ATPase and helicase activities of both XPB and XPD in Core7 to promote NER, whereas non-genuine NER substrates have no such effect. Moreover, the NER factor XPA activates unwinding of normal DNA by Core7, but inhibits the Core7 helicase activity in the presence of bulky lesions. Finally, the CAK module inhibits DNA binding by TFIIH and thereby enhances XPC-dependent specific recruitment of TFIIH. Our results support a tripartite lesion verification mechanism involving XPC, TFIIH, and XPA for efficient NER.
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30
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Khan I, Sommers JA, Brosh RM. Close encounters for the first time: Helicase interactions with DNA damage. DNA Repair (Amst) 2015; 33:43-59. [PMID: 26160335 DOI: 10.1016/j.dnarep.2015.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/05/2015] [Indexed: 01/17/2023]
Abstract
DNA helicases are molecular motors that harness the energy of nucleoside triphosphate hydrolysis to unwinding structured DNA molecules that must be resolved during cellular replication, DNA repair, recombination, and transcription. In vivo, DNA helicases are expected to encounter a wide spectrum of covalent DNA modifications to the sugar phosphate backbone or the nitrogenous bases; these modifications can be induced by endogenous biochemical processes or exposure to environmental agents. The frequency of lesion abundance can vary depending on the lesion type. Certain adducts such as oxidative base modifications can be quite numerous, and their effects can be helix-distorting or subtle perturbations to DNA structure. Helicase encounters with specific DNA lesions and more novel forms of DNA damage will be discussed. We will also review the battery of assays that have been used to characterize helicase-catalyzed unwinding of damaged DNA substrates. Characterization of the effects of specific DNA adducts on unwinding by various DNA repair and replication helicases has proven to be insightful for understanding mechanistic and biological aspects of helicase function in cellular DNA metabolism.
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Affiliation(s)
- Irfan Khan
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Joshua A Sommers
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH Biomedical Research Center, 251 Bayview Blvd, Baltimore, MD 21224, USA.
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31
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Buechner CN, Maiti A, Drohat AC, Tessmer I. Lesion search and recognition by thymine DNA glycosylase revealed by single molecule imaging. Nucleic Acids Res 2015; 43:2716-29. [PMID: 25712093 PMCID: PMC4357730 DOI: 10.1093/nar/gkv139] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The ability of DNA glycosylases to rapidly and efficiently detect lesions among a vast excess of nondamaged DNA bases is vitally important in base excision repair (BER). Here, we use single molecule imaging by atomic force microscopy (AFM) supported by a 2-aminopurine fluorescence base flipping assay to study damage search by human thymine DNA glycosylase (hTDG), which initiates BER of mutagenic and cytotoxic G:T and G:U mispairs in DNA. Our data reveal an equilibrium between two conformational states of hTDG–DNA complexes, assigned as search complex (SC) and interrogation complex (IC), both at target lesions and undamaged DNA sites. Notably, for both hTDG and a second glycosylase, hOGG1, which recognizes structurally different 8-oxoguanine lesions, the conformation of the DNA in the SC mirrors innate structural properties of their respective target sites. In the IC, the DNA is sharply bent, as seen in crystal structures of hTDG lesion recognition complexes, which likely supports the base flipping required for lesion identification. Our results support a potentially general concept of sculpting of glycosylases to their targets, allowing them to exploit the energetic cost of DNA bending for initial lesion sensing, coupled with continuous (extrahelical) base interrogation during lesion search by DNA glycosylases.
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Affiliation(s)
- Claudia N Buechner
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Atanu Maiti
- Department of Biochemistry and Molecular Biology and Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Alexander C Drohat
- Department of Biochemistry and Molecular Biology and Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ingrid Tessmer
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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32
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Fan L, DuPrez KT. XPB: An unconventional SF2 DNA helicase. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 117:174-181. [PMID: 25641424 DOI: 10.1016/j.pbiomolbio.2014.12.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/24/2014] [Accepted: 12/29/2014] [Indexed: 11/27/2022]
Abstract
XPB is a 3'-5' DNA helicase belonging to the superfamily 2 (SF2) of helicases. XPB is an essential core subunit of the eukaryotic basal transcription factor complex TFIIH which plays a dual role in transcription and DNA repair: 1) to facilitate the melting of the promoter during the initiation of RNA polymerase II transcription; 2) to unwind double stranded DNA (dsDNA) around a DNA lesion during nucleotide excision repair (NER). NER is a highly versatile DNA repair process which is able to remove a broad spectrum of structurally unrelated DNA helix-distorting lesions. The importance of a fully functional XPB is clearly illustrated by the severe clinical consequences associated with inherited defects in XPB including UV-hypersensitive syndromes xeroderma pigmentosum (XP), Cockayne syndrome (CS), combined XP and CS (XP/CS), and trichothiodystrophy (TTD). Here we discuss the structure and function of XPB in NER as well as the impact of a disease mutation in XP11BE patients with XP/CS complex manifestations.
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Affiliation(s)
- Li Fan
- 900 University Ave, Biochemistry Department, University of California, Riverside, CA 92521, USA.
| | - Kevin T DuPrez
- 900 University Ave, Biochemistry Department, University of California, Riverside, CA 92521, USA
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33
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Kawamura T, Anraku R, Hasegawa T, Tomikawa C, Hori H. Transfer RNA methyltransferases from Thermoplasma acidophilum, a thermoacidophilic archaeon. Int J Mol Sci 2014; 16:91-113. [PMID: 25546389 PMCID: PMC4307237 DOI: 10.3390/ijms16010091] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/12/2014] [Indexed: 02/03/2023] Open
Abstract
We investigated tRNA methyltransferase activities in crude cell extracts from the thermoacidophilic archaeon Thermoplasma acidophilum. We analyzed the modified nucleosides in native initiator and elongator tRNAMet, predicted the candidate genes for the tRNA methyltransferases on the basis of the tRNAMet and tRNALeu sequences, and characterized Trm5, Trm1 and Trm56 by purifying recombinant proteins. We found that the Ta0997, Ta0931, and Ta0836 genes of T. acidophilum encode Trm1, Trm56 and Trm5, respectively. Initiator tRNAMet from T. acidophilum strain HO-62 contained G+, m1I, and m22G, which were not reported previously in this tRNA, and the m2G26 and m22G26 were formed by Trm1. In the case of elongator tRNAMet, our analysis showed that the previously unidentified G modification at position 26 was a mixture of m2G and m22G, and that they were also generated by Trm1. Furthermore, purified Trm1 and Trm56 could methylate the precursor of elongator tRNAMet, which has an intron at the canonical position. However, the speed of methyl-transfer by Trm56 to the precursor RNA was considerably slower than that to the mature transcript, which suggests that Trm56 acts mainly on the transcript after the intron has been removed. Moreover, cellular arrangements of the tRNA methyltransferases in T. acidophilum are discussed.
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Affiliation(s)
- Takuya Kawamura
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime Univsersity, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Ryou Anraku
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime Univsersity, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Takahiro Hasegawa
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime Univsersity, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Chie Tomikawa
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime Univsersity, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
| | - Hiroyuki Hori
- Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime Univsersity, Bunkyo 3, Matsuyama, Ehime 790-8577, Japan.
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34
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Khan I, Suhasini AN, Banerjee T, Sommers JA, Kaplan DL, Kuper J, Kisker C, Brosh RM. Impact of age-associated cyclopurine lesions on DNA repair helicases. PLoS One 2014; 9:e113293. [PMID: 25409515 PMCID: PMC4237422 DOI: 10.1371/journal.pone.0113293] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 10/23/2014] [Indexed: 02/06/2023] Open
Abstract
8,5′ cyclopurine deoxynucleosides (cPu) are locally distorting DNA base lesions corrected by nucleotide excision repair (NER) and proposed to play a role in neurodegeneration prevalent in genetically defined Xeroderma pigmentosum (XP) patients. In the current study, purified recombinant helicases from different classifications based on sequence homology were examined for their ability to unwind partial duplex DNA substrates harboring a single site-specific cPu adduct. Superfamily (SF) 2 RecQ helicases (RECQ1, BLM, WRN, RecQ) were inhibited by cPu in the helicase translocating strand, whereas helicases from SF1 (UvrD) and SF4 (DnaB) tolerated cPu in either strand. SF2 Fe-S helicases (FANCJ, DDX11 (ChlR1), DinG, XPD) displayed marked differences in their ability to unwind the cPu DNA substrates. Archaeal Thermoplasma acidophilum XPD (taXPD), homologue to the human XPD helicase involved in NER DNA damage verification, was impeded by cPu in the non-translocating strand, while FANCJ was uniquely inhibited by the cPu in the translocating strand. Sequestration experiments demonstrated that FANCJ became trapped by the translocating strand cPu whereas RECQ1 was not, suggesting the two SF2 helicases interact with the cPu lesion by distinct mechanisms despite strand-specific inhibition for both. Using a protein trap to simulate single-turnover conditions, the rate of FANCJ or RECQ1 helicase activity was reduced 10-fold and 4.5-fold, respectively, by cPu in the translocating strand. In contrast, single-turnover rates of DNA unwinding by DDX11 and UvrD helicases were only modestly affected by the cPu lesion in the translocating strand. The marked difference in effect of the translocating strand cPu on rate of DNA unwinding between DDX11 and FANCJ helicase suggests the two Fe-S cluster helicases unwind damaged DNA by distinct mechanisms. The apparent complexity of helicase encounters with an unusual form of oxidative damage is likely to have important consequences in the cellular response to DNA damage and DNA repair.
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Affiliation(s)
- Irfan Khan
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland, United States of America
| | - Avvaru N. Suhasini
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland, United States of America
| | - Taraswi Banerjee
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland, United States of America
| | - Joshua A. Sommers
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland, United States of America
| | - Daniel L. Kaplan
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida, United States of America
| | - Jochen Kuper
- Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Würzburg, Würzburg, Germany
| | - Caroline Kisker
- Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Würzburg, Würzburg, Germany
| | - Robert M. Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland, United States of America
- * E-mail:
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35
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Ghoneim M, Spies M. Direct correlation of DNA binding and single protein domain motion via dual illumination fluorescence microscopy. NANO LETTERS 2014; 14:5920-31. [PMID: 25204359 PMCID: PMC4189620 DOI: 10.1021/nl502890g] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We report a dual illumination, single-molecule imaging strategy to dissect directly and in real-time the correlation between nanometer-scale domain motion of a DNA repair protein and its interaction with individual DNA substrates. The strategy was applied to XPD, an FeS cluster-containing DNA repair helicase. Conformational dynamics was assessed via FeS-mediated quenching of a fluorophore site-specifically incorporated into XPD. Simultaneously, binding of DNA molecules labeled with a spectrally distinct fluorophore was detected by colocalization of the DNA- and protein-derived signals. We show that XPD undergoes thermally driven conformational transitions that manifest in spatial separation of its two auxiliary domains. DNA binding does not strictly enforce a specific conformation. Interaction with a cognate DNA damage, however, stabilizes the compact conformation of XPD by increasing the weighted average lifetime of this state by 140% relative to an undamaged DNA. Our imaging strategy will be a valuable tool to study other FeS-containing nucleic acid processing enzymes.
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Affiliation(s)
- Mohamed Ghoneim
- Center
for Biophysics and Computational Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Department
of Biochemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Maria Spies
- Department
of Biochemistry, University of Iowa, Iowa City, Iowa 52242, United States
- E-mail: . Phone +1-319-335-3221
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36
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Hughes CD, Simons M, Mackenzie CE, Van Houten B, Kad NM. Single molecule techniques in DNA repair: a primer. DNA Repair (Amst) 2014; 20:2-13. [PMID: 24819596 DOI: 10.1016/j.dnarep.2014.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 10/25/2022]
Abstract
A powerful new approach has become much more widespread and offers insights into aspects of DNA repair unattainable with billions of molecules. Single molecule techniques can be used to image, manipulate or characterize the action of a single repair protein on a single strand of DNA. This allows search mechanisms to be probed, and the effects of force to be understood. These physical aspects can dominate a biochemical reaction, where at the ensemble level their nuances are obscured. In this paper we discuss some of the many technical advances that permit study at the single molecule level. We focus on DNA repair to which these techniques are actively being applied. DNA repair is also a process that encompasses so much of what single molecule studies benefit--searching for targets, complex formation, sequential biochemical reactions and substrate hand-off to name just a few. We discuss how single molecule biophysics is poised to transform our understanding of biological systems, in particular DNA repair.
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Affiliation(s)
- Craig D Hughes
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Michelle Simons
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Cassidy E Mackenzie
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Neil M Kad
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
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37
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Spies M. Two steps forward, one step back: determining XPD helicase mechanism by single-molecule fluorescence and high-resolution optical tweezers. DNA Repair (Amst) 2014; 20:58-70. [PMID: 24560558 DOI: 10.1016/j.dnarep.2014.01.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 12/31/2013] [Accepted: 01/13/2014] [Indexed: 11/17/2022]
Abstract
XPD-like helicases constitute a prominent DNA helicase family critical for many aspects of genome maintenance. These enzymes share a unique structural feature, an auxiliary domain stabilized by an iron-sulphur (FeS) cluster, and a 5'-3' polarity of DNA translocation and duplex unwinding. Biochemical analyses alongside two single-molecule approaches, total internal reflection fluorescence microscopy and high-resolution optical tweezers, have shown how the unique structural features of XPD helicase and its specific patterns of substrate interactions tune the helicase for its specific cellular function and shape its molecular mechanism. The FeS domain forms a duplex separation wedge and contributes to an extended DNA binding site. Interactions within this site position the helicase in an orientation to unwind the duplex, control the helicase rate, and verify the integrity of the translocating strand. Consistent with its cellular role, processivity of XPD is limited and is defined by an idiosyncratic stepping kinetics. DNA duplex separation occurs in single base pair steps punctuated by frequent backward steps and conformational rearrangements of the protein-DNA complex. As such, the helicase in isolation mainly stabilizes spontaneous base pair opening and exhibits a limited ability to unwind stable DNA duplexes. The presence of a cognate ssDNA binding protein converts XPD into a vigorous helicase by destabilizing the upstream dsDNA as well as by trapping the unwound strands. Remarkably, the two proteins can co-exist on the same DNA strand without competing for binding. The current model of the XPD unwinding mechanism will be discussed along with possible modifications to this mechanism by the helicase interacting partners and unique features of such bio-medically important XPD-like helicases as FANCJ (BACH1), RTEL1 and CHLR1 (DDX11).
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Affiliation(s)
- Maria Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, IA 52242, United States.
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