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Nayak S, Calvo JA, Cantor SB. Targeting translesion synthesis (TLS) to expose replication gaps, a unique cancer vulnerability. Expert Opin Ther Targets 2021; 25:27-36. [PMID: 33416413 PMCID: PMC7837368 DOI: 10.1080/14728222.2021.1864321] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 12/11/2020] [Indexed: 02/09/2023]
Abstract
Introduction: Translesion synthesis (TLS) is a DNA damage tolerance (DDT) mechanism that employs error-prone polymerases to bypass replication blocking DNA lesions, contributing to a gain in mutagenesis and chemo-resistance. However, recent findings illustrate an emerging role for TLS in replication gap suppression (RGS), distinct from its role in post-replication gap filling. Here, TLS protects cells from replication stress (RS)-induced toxic single-stranded DNA (ssDNA) gaps that accumulate in the wake of active replication. Intriguingly, TLS-mediated RGS is specifically observed in several cancer cell lines and contributes to their survival. Thus, targeting TLS has the potential to uniquely eradicate tumors without harming non-cancer tissues. Areas Covered: This review provides an innovative perspective on the role of TLS beyond its canonical function of lesion bypass or post-replicative gap filling. We provide a comprehensive analysis that underscores the emerging role of TLS as a cancer adaptation necessary to overcome the replication stress response (RSR), an anti-cancer barrier. Expert Opinion: TLS RGS is critical for tumorigenesis and is a new hallmark of cancer. Although the exact mechanism and extent of TLS dependency in cancer is still emerging, TLS inhibitors have shown promise as an anti-cancer therapy in selectively targeting this unique cancer vulnerability.
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Affiliation(s)
- Sumeet Nayak
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School , Worcester, MA USA
| | - Jennifer A Calvo
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School , Worcester, MA USA
| | - Sharon B Cantor
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School , Worcester, MA USA
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Perera HM, Trakselis MA. Amidst multiple binding orientations on fork DNA, Saccharolobus MCM helicase proceeds N-first for unwinding. eLife 2019; 8:46096. [PMID: 31661075 PMCID: PMC6831031 DOI: 10.7554/elife.46096] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 10/23/2019] [Indexed: 11/13/2022] Open
Abstract
DNA replication requires that the duplex genomic DNA strands be separated; a function that is implemented by ring-shaped hexameric helicases in all Domains. Helicases are composed of two domains, an N- terminal DNA binding domain (NTD) and a C- terminal motor domain (CTD). Replication is controlled by loading of helicases at origins of replication, activation to preferentially encircle one strand, and then translocation to begin separation of the two strands. Using a combination of site-specific DNA footprinting, single-turnover unwinding assays, and unique fluorescence translocation monitoring, we have been able to quantify the binding distribution and the translocation orientation of Saccharolobus (formally Sulfolobus) solfataricus MCM on DNA. Our results show that both the DNA substrate and the C-terminal winged-helix (WH) domain influence the orientation but that translocation on DNA proceeds N-first.
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Affiliation(s)
- Himasha M Perera
- Department of Chemistry and Biochemistry, Baylor University, Waco, United States
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, United States
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Perera HM, Behrmann MS, Hoang JM, Griffin WC, Trakselis MA. Contacts and context that regulate DNA helicase unwinding and replisome progression. Enzymes 2019; 45:183-223. [PMID: 31627877 DOI: 10.1016/bs.enz.2019.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hexameric DNA helicases involved in the separation of duplex DNA at the replication fork have a universal architecture but have evolved from two separate protein families. The consequences are that the regulation, translocation polarity, strand specificity, and architectural orientation varies between phage/bacteria to that of archaea/eukaryotes. Once assembled and activated for single strand DNA translocation and unwinding, the DNA polymerase couples tightly to the helicase forming a robust replisome complex. However, this helicase-polymerase interaction can be challenged by various forms of endogenous or exogenous agents that can stall the entire replisome or decouple DNA unwinding from synthesis. The consequences of decoupling can be severe, leading to a build-up of ssDNA requiring various pathways for replication fork restart. All told, the hexameric helicase sits prominently at the front of the replisome constantly responding to a variety of obstacles that require transient unwinding/reannealing, traversal of more stable blocks, and alternations in DNA unwinding speed that regulate replisome progression.
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Affiliation(s)
- Himasha M Perera
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States
| | - Megan S Behrmann
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States
| | - Joy M Hoang
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States
| | - Wezley C Griffin
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, United States.
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Graham BW, Bougoulias ME, Dodge KL, Thaxton CT, Olaso D, Tao Y, Young NL, Marshall AG, Trakselis MA. Control of Hexamerization, Assembly, and Excluded Strand Specificity for the Sulfolobus solfataricus MCM Helicase. Biochemistry 2018; 57:5672-5682. [DOI: 10.1021/acs.biochem.8b00766] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brian W. Graham
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Michael E. Bougoulias
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Katie L. Dodge
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Carly T. Thaxton
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Danae Olaso
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
| | - Yeqing Tao
- Department of Chemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Nicolas L. Young
- Verna & Marrs McLean Department of Biochemistry & Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030-3411, United States
| | - Alan G. Marshall
- Department of Chemistry, Florida State University, Tallahassee, Florida 32306, United States
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Michael A. Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798, United States
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Bell SD. Initiation of DNA Replication in the Archaea. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:99-115. [PMID: 29357055 DOI: 10.1007/978-981-10-6955-0_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Organisms within the archaeal domain of life possess a simplified version of the eukaryotic DNA replication machinery. While some archaea possess a bacterial-like mode of DNA replication with single origins of replication per chromosome, the majority of species characterized to date possess chromosomes with multiple replication origins. Genetic, structural, and biochemical studies have revealed the nature of archaeal origin specification. Recent work has begun to shed light on the mechanisms of replication initiation in these organisms.
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Affiliation(s)
- Stephen D Bell
- Department of Molecular and Cellular Biochemistry, Department of Biology, Indiana University, Bloomington, IN, USA.
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Swuec P, Costa A. DNA replication and inter-strand crosslink repair: Symmetric activation of dimeric nanomachines? Biophys Chem 2016; 225:15-19. [PMID: 27989548 DOI: 10.1016/j.bpc.2016.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 10/28/2016] [Accepted: 11/01/2016] [Indexed: 10/20/2022]
Abstract
Eukaryotic DNA replication initiation and the Fanconi anemia pathway of interstrand crosslink repair both revolve around the recruitment of a set of DNA-processing factors onto a dimeric protein complex, which functions as a loading platform (MCM and FANCI-FANCD2 respectively). Here we compare and contrast the two systems, identifying a set of unresolved mechanistic questions. How is the dimeric loading platform assembled on the DNA? How can equivalent covalent modification of both factors in a dimer be achieved? Are multicomponent DNA-interacting machines built symmetrically around their dimeric loading platform? Recent biochemical reconstitution studies are starting to shed light on these issues.
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Affiliation(s)
- Paolo Swuec
- Macromolecular Machines Laboratory, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms, EN6 3LD, UK
| | - Alessandro Costa
- Macromolecular Machines Laboratory, Clare Hall Laboratory, The Francis Crick Institute, Blanche Lane, South Mimms, EN6 3LD, UK.
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