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Schiopu I, Dragomir I, Asandei A. Single molecule technique unveils the role of electrostatic interactions in ssDNA-gp32 molecular complex stability. RSC Adv 2024; 14:5449-5460. [PMID: 38352678 PMCID: PMC10862658 DOI: 10.1039/d3ra07746b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 02/07/2024] [Indexed: 02/16/2024] Open
Abstract
The exploration of single-strand DNA-binding protein (SSB)-ssDNA interactions and their crucial roles in essential biological processes lagged behind other types of protein-nucleic acid interactions, such as protein-dsDNA and protein-RNA interactions. The ssDNA binding protein gene product 32 (gp32) of the T4 bacteriophage is a central integrating component of the replication complex that must continuously bind to and unbind from transiently exposed template strands during the DNA synthesis. To gain deeper insights into the electrostatic conditions influencing the stability of the ssDNA-gp32 molecular complex, like the salt concentration or some metal ions proven to specifically bind to gp32, we employed a method that performs rapid measurements of the DNA-protein stability using an α-Hemolysin (α-HL) protein nanopore. We indirectly probed the stability of a protein-nucleic acid complex by monitoring the dissociation process between the gp32 protein and the ssDNA molecular complex in single-molecular electrophysiology experiments, but also through fluorescence spectroscopy techniques. We have shown that the complex is more stable in 0.5 M KCl solution than in 2 M KCl solution and that the presence of Zn2+ ions further increases this stability for any salt used in the present study. This method can be applied to other nucleic acid-protein molecular complexes, as well as for an accurate determination of the drug-protein carrier stability.
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Affiliation(s)
- Irina Schiopu
- The Institute of Interdisciplinary Research, Department of Exact Sciences and Natural Sciences, "Alexandru Ioan Cuza" University of Iaşi 700506 Iasi Romania
| | - Isabela Dragomir
- The Institute of Interdisciplinary Research, Department of Exact Sciences and Natural Sciences, "Alexandru Ioan Cuza" University of Iaşi 700506 Iasi Romania
| | - Alina Asandei
- The Institute of Interdisciplinary Research, Department of Exact Sciences and Natural Sciences, "Alexandru Ioan Cuza" University of Iaşi 700506 Iasi Romania
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2
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Fousek-Schuller VJ, Borgstahl GEO. The Intriguing Mystery of RPA Phosphorylation in DNA Double-Strand Break Repair. Genes (Basel) 2024; 15:167. [PMID: 38397158 PMCID: PMC10888239 DOI: 10.3390/genes15020167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/25/2024] Open
Abstract
Human Replication Protein A (RPA) was historically discovered as one of the six components needed to reconstitute simian virus 40 DNA replication from purified components. RPA is now known to be involved in all DNA metabolism pathways that involve single-stranded DNA (ssDNA). Heterotrimeric RPA comprises several domains connected by flexible linkers and is heavily regulated by post-translational modifications (PTMs). The structure of RPA has been challenging to obtain. Various structural methods have been applied, but a complete understanding of RPA's flexible structure, its function, and how it is regulated by PTMs has yet to be obtained. This review will summarize recent literature concerning how RPA is phosphorylated in the cell cycle, the structural analysis of RPA, DNA and protein interactions involving RPA, and how PTMs regulate RPA activity and complex formation in double-strand break repair. There are many holes in our understanding of this research area. We will conclude with perspectives for future research on how RPA PTMs control double-strand break repair in the cell cycle.
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Affiliation(s)
| | - Gloria E. O. Borgstahl
- Eppley Institute for Research in Cancer & Allied Diseases, UNMC, Omaha, NE 68198-6805, USA
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3
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Lithgo RM, Hanževački M, Harris G, Kamps JJAG, Holden E, Gianga TM, Benesch JLP, Jäger CM, Croft AK, Hussain R, Hobman JL, Orville AM, Quigley A, Carr SB, Scott DJ. The adaptability of the ion-binding site by the Ag(I)/Cu(I) periplasmic chaperone SilF. J Biol Chem 2023; 299:105331. [PMID: 37820867 PMCID: PMC10656224 DOI: 10.1016/j.jbc.2023.105331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 09/30/2023] [Accepted: 10/04/2023] [Indexed: 10/13/2023] Open
Abstract
The periplasmic chaperone SilF has been identified as part of an Ag(I) detoxification system in Gram-negative bacteria. Sil proteins also bind Cu(I) but with reported weaker affinity, therefore leading to the designation of a specific detoxification system for Ag(I). Using isothermal titration calorimetry, we show that binding of both ions is not only tighter than previously thought but of very similar affinities. We investigated the structural origins of ion binding using molecular dynamics and QM/MM simulations underpinned by structural and biophysical experiments. The results of this analysis showed that the binding site adapts to accommodate either ion, with key interactions with the solvent in the case of Cu(I). The implications of this are that Gram-negative bacteria do not appear to have evolved a specific Ag(I) efflux system but take advantage of the existing Cu(I) detoxification system. Therefore, there are consequences for how we define a particular metal resistance mechanism and understand its evolution in the environment.
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Affiliation(s)
- Ryan M Lithgo
- School of Biosciences, Sutton Bonington Campus, University of Nottingham, Leicestershire, United Kingdom; Membrane Protein Laboratory, Diamond Light Source, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom; Diamond Light Source, Diamond House, Rutherford Appleton Laboratories, Didcot, Oxfordshire, United Kingdom; Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom
| | - Marko Hanževački
- Department of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham, United Kingdom
| | - Gemma Harris
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom
| | - Jos J A G Kamps
- Diamond Light Source, Diamond House, Rutherford Appleton Laboratories, Didcot, Oxfordshire, United Kingdom; Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom
| | - Ellie Holden
- Department of Chemistry, University of Oxford, Oxford, Oxfordshire, United Kingdom
| | - Tiberiu-Marius Gianga
- Diamond Light Source, Diamond House, Rutherford Appleton Laboratories, Didcot, Oxfordshire, United Kingdom
| | - Justin L P Benesch
- Department of Chemistry, University of Oxford, Oxford, Oxfordshire, United Kingdom
| | - Christof M Jäger
- Department of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham, United Kingdom; Department of Data Science and Modelling, Pharmaceutical Sciences, R&D, AstraZeneca Gothenburg, Mölndal, Sweden
| | - Anna K Croft
- Department of Chemical Engineering, University of Loughborough, Loughborough, United Kingdom
| | - Rohannah Hussain
- Diamond Light Source, Diamond House, Rutherford Appleton Laboratories, Didcot, Oxfordshire, United Kingdom
| | - Jon L Hobman
- School of Biosciences, Sutton Bonington Campus, University of Nottingham, Leicestershire, United Kingdom
| | - Allen M Orville
- Diamond Light Source, Diamond House, Rutherford Appleton Laboratories, Didcot, Oxfordshire, United Kingdom; Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom
| | - Andrew Quigley
- Membrane Protein Laboratory, Diamond Light Source, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom; Diamond Light Source, Diamond House, Rutherford Appleton Laboratories, Didcot, Oxfordshire, United Kingdom; Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom
| | - Stephen B Carr
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom; Department of Chemistry, University of Oxford, Oxford, Oxfordshire, United Kingdom
| | - David J Scott
- School of Biosciences, Sutton Bonington Campus, University of Nottingham, Leicestershire, United Kingdom; Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom.
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4
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Mahmoud SF, Elewa YH, Nomir AG, Rashwan AM, Noreldin AE. Calbindin Has a Potential Spatiotemporal Correlation with Proliferation and Apoptosis in the Postnatal Rat Kidney. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1705-1717. [PMID: 37584523 DOI: 10.1093/micmic/ozad080] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/02/2023] [Accepted: 07/18/2023] [Indexed: 08/17/2023]
Abstract
The protein calbindin-D28k modulates calcium reabsorption in the kidney. Here, we aimed to study the influence of proliferation and apoptosis in different compartments of the kidney on the developmental function of calbindin. Using immunohistochemistry, we investigated the postnatal development of rats' kidneys by using calbindin, proliferative cell nuclear antigen (PCNA), and apoptotic single-stranded DNA (ssDNA). In the neonatal stage (1-day and 1-week-old rats), calbindin showed a positive reaction in the distal convoluted tubule (DCT), a short nephron segment between the macula densa, collecting ducts, and tubules. Moreover, the localization of calbindin was restricted to immature nephrons and mesenchymal tissues. Furthermore, PCNA immunoreactivity was moderate in early-developed podocytes with no reactivity in other renal tubules. The ssDNA immunoreactivity was moderate in the undifferentiated nephron. Then, in the mature stage (3 and 6 weeks old), there was an intense calbindin reaction in DCT but a moderate reaction to PCNA and ssDNA in podocytes. A more intense calbindin reactivity was found in the adult stage (2- and 3-month-old rats) in DCT and collecting tubules. Therefore, in this study, calbindin localization showed an inverse relationship with PCNA and ssDNA of the nephron compartments, which might reflect the efficiency of bone-building and muscle contraction during animal development.
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Affiliation(s)
- Sahar F Mahmoud
- Department of Histology and Cytology, Faculty of Veterinary Medicine, Damanhour University, Al Gomhouria St, Scientific Campus, Damanhour 22511, Egypt
| | - Yaser H Elewa
- Department of Histology, Faculty of Veterinary Medicine, Zagazig University, El Tagneed St, Agriculture Square, Zagazig 44519, Egypt
- Faculty of Veterinary Medicine, Basic Veterinary Sciences, Hokkaido University, Kita Ku, Kita18, Nishi 9 Jo, Sapporo 060-0818, Japan
| | - Ahmed G Nomir
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Damanhour University, Al Gomhouria St, Scientific Campus, Damanhour 22511, Egypt
| | - Ahmed M Rashwan
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Damanhour University, Al Gomhouria St, Scientific Campus, Damanhour 22511, Egypt
- Laboratory of Life science frontiers, Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Ahmed E Noreldin
- Department of Histology and Cytology, Faculty of Veterinary Medicine, Damanhour University, Al Gomhouria St, Scientific Campus, Damanhour 22511, Egypt
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Madru C, Martínez-Carranza M, Laurent S, Alberti AC, Chevreuil M, Raynal B, Haouz A, Le Meur RA, Delarue M, Henneke G, Flament D, Krupovic M, Legrand P, Sauguet L. DNA-binding mechanism and evolution of replication protein A. Nat Commun 2023; 14:2326. [PMID: 37087464 PMCID: PMC10122647 DOI: 10.1038/s41467-023-38048-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 04/13/2023] [Indexed: 04/24/2023] Open
Abstract
Replication Protein A (RPA) is a heterotrimeric single stranded DNA-binding protein with essential roles in DNA replication, recombination and repair. Little is known about the structure of RPA in Archaea, the third domain of life. By using an integrative structural, biochemical and biophysical approach, we extensively characterize RPA from Pyrococcus abyssi in the presence and absence of DNA. The obtained X-ray and cryo-EM structures reveal that the trimerization core and interactions promoting RPA clustering on ssDNA are shared between archaea and eukaryotes. However, we also identified a helical domain named AROD (Acidic Rpa1 OB-binding Domain), and showed that, in Archaea, RPA forms an unanticipated tetrameric supercomplex in the absence of DNA. The four RPA molecules clustered within the tetramer could efficiently coat and protect stretches of ssDNA created by the advancing replisome. Finally, our results provide insights into the evolution of this primordial replication factor in eukaryotes.
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Affiliation(s)
- Clément Madru
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Markel Martínez-Carranza
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Sébastien Laurent
- Univ Brest, Ifremer, CNRS, Biologie et Ecologie des Ecoystèmes marins profonds (BEEP), F-29280, Plouzané, France
| | - Alessandra C Alberti
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Maelenn Chevreuil
- Molecular Biophysics Platform, C2RT, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Bertrand Raynal
- Molecular Biophysics Platform, C2RT, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Ahmed Haouz
- Crystallography Platform, C2RT, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Rémy A Le Meur
- Biological NMR Platform & HDX, C2RT, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Marc Delarue
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
| | - Ghislaine Henneke
- Univ Brest, Ifremer, CNRS, Biologie et Ecologie des Ecoystèmes marins profonds (BEEP), F-29280, Plouzané, France
| | - Didier Flament
- Univ Brest, Ifremer, CNRS, Biologie et Ecologie des Ecoystèmes marins profonds (BEEP), F-29280, Plouzané, France
| | - Mart Krupovic
- Archaeal Virology Unit, Institut Pasteur, Université Paris Cité, CNRS, UMR 6047, Paris, France
| | - Pierre Legrand
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France
- Synchrotron SOLEIL, HelioBio group, L'Orme des Merisiers, 91190, Saint-Aubin, France
| | - Ludovic Sauguet
- Architecture and Dynamics of Biological Macromolecules, Institut Pasteur, Université Paris Cité, CNRS, UMR 3528, Paris, France.
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Algethami M, Toss MS, Woodcock CL, Jaipal C, Brownlie J, Shoqafi A, Alblihy A, Mesquita KA, Green AR, Mongan NP, Jeyapalan JN, Rakha EA, Madhusudan S. Unravelling the clinicopathological and functional significance of replication protein A (RPA) heterotrimeric complex in breast cancers. NPJ Breast Cancer 2023; 9:18. [PMID: 36997566 PMCID: PMC10063624 DOI: 10.1038/s41523-023-00524-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
Replication Protein A (RPA), a heterotrimeric complex consisting of RPA1, 2, and 3 subunits, is a single-stranded DNA (ssDNA)-binding protein that is critically involved in replication, checkpoint regulation and DNA repair. Here we have evaluated RPA in 776 pure ductal carcinomas in situ (DCIS), 239 DCIS that co-exist with invasive breast cancer (IBC), 50 normal breast tissue and 4221 IBC. Transcriptomic [METABRIC cohort (n = 1980)] and genomic [TCGA cohort (n = 1090)] evaluations were completed. Preclinically, RPA deficient cells were tested for cisplatin sensitivity and Olaparib induced synthetic lethality. Low RPA linked to aggressive DCIS, aggressive IBC, and shorter survival outcomes. At the transcriptomic level, low RPA tumours overexpress pseudogene/lncRNA as well as genes involved in chemical carcinogenesis, and drug metabolism. Low RPA remains linked with poor outcome. RPA deficient cells are sensitive to cisplatin and Olaparib induced synthetic lethality. We conclude that RPA directed precision oncology strategy is feasible in breast cancers.
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Affiliation(s)
- Mashael Algethami
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
| | - Michael S Toss
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
- Department of Pathology, Nottingham University Hospital, City Campus, Hucknall Road, Nottingham, NG51PB, UK
| | - Corinne L Woodcock
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
- Faculty of Medicine and Health Sciences, Centre for Cancer Sciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire, LE12 5RD, UK
| | - Chandar Jaipal
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
| | - Juliette Brownlie
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
| | - Ahmed Shoqafi
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
| | - Adel Alblihy
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
- Medical Center, King Fahad Security College (KFSC), Riyadh, 11461, Saudi Arabia
| | - Katia A Mesquita
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
| | - Andrew R Green
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
| | - Nigel P Mongan
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
- Department of Pharmacology, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Jennie N Jeyapalan
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
- Department of Pathology, Nottingham University Hospital, City Campus, Hucknall Road, Nottingham, NG51PB, UK
| | - Emad A Rakha
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK
- Medical Center, King Fahad Security College (KFSC), Riyadh, 11461, Saudi Arabia
| | - Srinivasan Madhusudan
- Nottingham Biodiscovery Institute, School of Medicine, University of Nottingham, University Park, Nottingham, NG7 3RD, UK.
- Department of Oncology, Nottingham University Hospitals, Nottingham, NG51PB, UK.
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7
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Novel Epitopes Mapping of African Swine Fever Virus CP312R Protein Using Monoclonal Antibodies. Viruses 2023; 15:v15020557. [PMID: 36851771 PMCID: PMC9963768 DOI: 10.3390/v15020557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 02/10/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
African Swine Fever (ASF) is a highly contagious and lethal pig disease and poses a huge threat to the pig industry worldwide. ASF virus (ASFV) encodes more than 150 different proteins, but the biological properties of most viral proteins are still unknown. ASFV CP312R protein has been proven to be one of the most immunogenic proteins during ASFV infection in pigs; however, its specific epitopes have yet to be identified. In this study, we verified the immunogenicity of CP312R protein in the sera from attenuated ASFV-inoculated pigs. We generated seven anti-ASFV CP312R mouse monoclonal antibodies (mAbs) from mice immunized with recombinant CP312R protein (rCP312R). All seven mAbs are the IgG2b-Kappa isotype and specifically interacted with the CP312R protein expressed in various cells that were infected by ASFVs or transfected with plasmid CP312R. The epitope mapping was performed by using these characterized mAbs and the peptide scanning (Pepscan) method followed by Western blot. As a result, two antigenic determinant regions were identified: two of the seven mAbs recognized the 122KNEQGEEIYP131 amino acids, and the remaining five mAbs recognized the 78DEEVIRMNAE87 amino acids of the CP312R protein. These antigenic determinants of CP312R are conserved in different ASFV strains of seven genotypes. By using the characterized mAb, confocal microscopy observation revealed that the CP312R was mainly localized in the cytoplasm and, to some extent, in nuclei and on the nuclear membrane of infected host cells. In summary, our results benefit our understanding on the antigenic regions of ASFV CP312R and help to develop better serological diagnosis of ASF and vaccine research.
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Li B, Liu J, Xu L, Xu Q, Liu Z, Liu T. Comprehensive Analysis of NABP2 as a Prognostic Biomarker and Its Correlation with Immune Infiltration in Hepatocellular Carcinoma. J Inflamm Res 2023; 16:1783-1804. [PMID: 37113629 PMCID: PMC10128078 DOI: 10.2147/jir.s403370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Background The DNA binding protein NABP2 (nucleic acid binding protein 2) is a member of the SSB (single-stranded DNA-binding) protein family, which is involved in DNA damage repair. Its prognostic significance and relationship with immune infiltration in hepatocellular carcinoma (HCC), however, remain unknown. Methods The purpose of this study was to estimate the prognostic value of NABP2 and to investigate its possible immune function in HCC. By applying multiple bioinformatics methods, we gathered and analysed data from The Cancer Genome Atlas (TCGA), Cancer Cell Lineage Encyclopedia (CCLE), and Gene Expression Omnibus (GEO) to investigate the potential oncogenic and cancer-promoting role of NABP2, including the differential expression, prognostic value, immune cell infiltration association, and drug sensitivity of NABP2 in HCC. Immunohistochemistry and Western blotting were used to validate the expression of NABP2 in HCC. The knockdown of NABP2 expression by siRNA was further used to validate its role in hepatocellular carcinoma. Results Our findings indicated that NABP2 was overexpressed in HCC samples and was related to poor survival, clinical stage, and tumour grade in HCC patients. Analysis of functional enrichment indicated that NABP2 was potentially involved in the cell cycle, DNA replication, G2M checkpoint, E2F targets, apoptosis, P53 signalling, TGFA signalling via NF-κB, and so on. NABP2 was shown to be significantly linked to immune cell infiltration and immunological checkpoints in HCC. Analyses of drug sensitivity predict a number of drugs that could potentially be used to target NABP2. Moreover, in vitro experiments verified the promoting effect of NABP2 on the migration and proliferation of hepatocellular carcinoma cells. Conclusion Based on these findings, NABP2 appears to be a candidate biomarker for HCC prognosis and immunotherapy.
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Affiliation(s)
- Bowen Li
- Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, 330000, People’s Republic of China
| | - Jinghang Liu
- Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, 330000, People’s Republic of China
| | - Liangzhi Xu
- Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, 330000, People’s Republic of China
| | - Qi Xu
- Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, 330000, People’s Republic of China
| | - Zhaohui Liu
- Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, 330000, People’s Republic of China
| | - Tiande Liu
- Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, 330000, People’s Republic of China
- Correspondence: Tiande Liu, Departments of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, 330000, People’s Republic of China, Tel +8613479101447, Email
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9
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Interdomain dynamics in human Replication Protein A regulates kinetics and thermodynamics of its binding to ssDNA. PLoS One 2023; 18:e0278396. [PMID: 36656834 PMCID: PMC9851514 DOI: 10.1371/journal.pone.0278396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 11/15/2022] [Indexed: 01/20/2023] Open
Abstract
Human Replication Protein A (hRPA) is a multidomain protein that interacts with ssDNA intermediates to provide the latter much-needed stability during DNA metabolism and maintain genomic integrity. Although the ssDNA organization with hRPA was studied recently through experimental means, characterizing the underlying mechanism at the atomic level remains challenging because of the dynamic domain architecture of hRPA and poorly understood heterogeneity of ssDNA-protein interactions. Here, we used a computational framework, precisely tailored to capture protein-ssDNA interactions, and investigated the binding of hRPA with a 60 nt ssDNA. Two distinct binding mechanisms are realized based on the hRPA domain flexibility. For a rigid domain architecture of hRPA, ssDNA binds sequentially with hRPA domains, resulting in slow association kinetics. The binding pathway involves the formation of stable and distinct intermediate states. On contrary, for a flexible domain architecture of hRPA, ssDNA binds synergistically to the A and B domains followed by the rest of hRPA. The domain dynamics in hRPA alleviates the free energy cost of domain orientation necessary for specific binding with ssDNA, leading to fast association kinetics along a downhill binding free energy landscape. An ensemble of free energetically degenerate intermediate states is encountered that makes it arduous to characterize them structurally. An excellent match between our results with the available experimental observations provides new insights into the rich dynamics of hRPA binding to ssDNA and in general paves the way to investigate intricate details of ssDNA-protein interactions, crucial for cellular functioning.
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10
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Ratre V, Hemmadi V, Biswas S, Biswas M. Identification and Preliminary Characterization of a Novel Single-Stranded DNA Binding Protein of Staphylococcus aureus Phage Phi11 Expressed in Escherichia coli. Mol Biotechnol 2022; 65:922-933. [DOI: 10.1007/s12033-022-00598-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 10/28/2022] [Indexed: 11/10/2022]
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11
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Extended DNA binding interfaces beyond the canonical SAP domain contribute to the function of replication stress regulator SDE2 at DNA replication forks. J Biol Chem 2022; 298:102268. [PMID: 35850305 PMCID: PMC9399289 DOI: 10.1016/j.jbc.2022.102268] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 11/25/2022] Open
Abstract
Elevated DNA replication stress causes instability of the DNA replication fork and increased DNA mutations, which underlies tumorigenesis. The DNA replication stress regulator silencing-defective 2 (SDE2) is known to bind to TIMELESS (TIM), a protein of the fork protection complex, and enhances its stability, thereby supporting replisome activity at DNA replication forks. However, the DNA-binding activity of SDE2 is not well defined. Here, we structurally and functionally characterize a new conserved DNA-binding motif related to the SAP (SAF-A/B, Acinus, PIAS) domain in human SDE2 and establish its preference for ssDNA. Our NMR solution structure of the SDE2SAP domain reveals a helix-extended loop-helix core with the helices aligned parallel to each other, consistent with known canonical SAP folds. Notably, we have shown that the DNA interaction of this SAP domain extends beyond the core SAP domain and is augmented by two lysine residues in the C-terminal tail, which is uniquely positioned adjacent to the SAP motif and conserved in the pre-mRNA splicing factor SF3A3. Furthermore, we found that mutation in the SAP domain and extended C terminus not only disrupts ssDNA binding but also impairs TIM localization at replication forks, thus inhibiting efficient fork progression. Taken together, our results establish SDE2SAP as an essential element for SDE2 to exert its role in preserving replication fork integrity via fork protection complex regulation and highlight the structural diversity of the DNA–protein interactions achieved by a specialized DNA-binding motif.
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12
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Chen L, Chen L, Chen H, Zhang H, Dong P, Sun L, Huang X, Lin P, Wu L, Jing D, Qian Y, Wu Y. Structural insights into the CP312R protein of the African swine fever virus. Biochem Biophys Res Commun 2022; 624:68-74. [DOI: 10.1016/j.bbrc.2022.07.091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 07/23/2022] [Indexed: 01/19/2023]
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13
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Lei T, Du S, Peng Z, Chen L. Multifaceted regulation and functions of 53BP1 in NHEJ‑mediated DSB repair (Review). Int J Mol Med 2022; 50:90. [PMID: 35583003 PMCID: PMC9162042 DOI: 10.3892/ijmm.2022.5145] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 04/29/2022] [Indexed: 12/02/2022] Open
Abstract
The repair of DNA double-strand breaks (DSBs) is crucial for the preservation of genomic integrity and the maintenance of cellular homeostasis. Non-homologous DNA end joining (NHEJ) is the predominant repair mechanism for any type of DNA DSB during the majority of the cell cycle. NHEJ defects regulate tumor sensitivity to ionizing radiation and anti-neoplastic agents, resulting in immunodeficiencies and developmental abnormalities in malignant cells. p53-binding protein 1 (53BP1) is a key mediator involved in DSB repair, which functions to maintain a balance in the repair pathway choices and in preserving genomic stability. 53BP1 promotes DSB repair via NHEJ and antagonizes DNA end overhang resection. At present, novel lines of evidence have revealed the molecular mechanisms underlying the recruitment of 53BP1 and DNA break-responsive effectors to DSB sites, and the promotion of NHEJ-mediated DSB repair via 53BP1, while preventing homologous recombination. In the present review article, recent advances made in the elucidation of the structural and functional characteristics of 53BP1, the mechanisms of 53BP1 recruitment and interaction with the reshaping of the chromatin architecture around DSB sites, the post-transcriptional modifications of 53BP1, and the up- and downstream pathways of 53BP1 are discussed. The present review article also focuses on the application perspectives, current challenges and future directions of 53BP1 research.
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Affiliation(s)
- Tiantian Lei
- Department of Pharmacy, Women and Children's Hospital of Chongqing Medical University, Chongqing 401147, P.R. China
| | - Suya Du
- Department of Clinical Pharmacy, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan 610041, P.R. China
| | - Zhe Peng
- Department of Pharmacy, Women and Children's Hospital of Chongqing Medical University, Chongqing 401147, P.R. China
| | - Lin Chen
- Department of Pharmacy, Women and Children's Hospital of Chongqing Medical University, Chongqing 401147, P.R. China
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14
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Bianco PR. OB-fold Families of Genome Guardians: A Universal Theme Constructed From the Small β-barrel Building Block. Front Mol Biosci 2022; 9:784451. [PMID: 35223988 PMCID: PMC8881015 DOI: 10.3389/fmolb.2022.784451] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
The maintenance of genome stability requires the coordinated actions of multiple proteins and protein complexes, that are collectively known as genome guardians. Within this broadly defined family is a subset of proteins that contain oligonucleotide/oligosaccharide-binding folds (OB-fold). While OB-folds are widely associated with binding to single-stranded DNA this view is no longer an accurate depiction of how these domains are utilized. Instead, the core of the OB-fold is modified and adapted to facilitate binding to a variety of DNA substrates (both single- and double-stranded), phospholipids, and proteins, as well as enabling catalytic function to a multi-subunit complex. The flexibility accompanied by distinctive oligomerization states and quaternary structures enables OB-fold genome guardians to maintain the integrity of the genome via a myriad of complex and dynamic, protein-protein; protein-DNA, and protein-lipid interactions in both prokaryotes and eukaryotes.
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Affiliation(s)
- Piero R. Bianco
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, United States
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15
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Wang S, Bai J. Functions and roles of IFIX, a member of the human HIN-200 family, in human diseases. Mol Cell Biochem 2022; 477:771-780. [PMID: 35039991 DOI: 10.1007/s11010-021-04297-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/04/2021] [Indexed: 11/25/2022]
Abstract
Pyrin and hematopoietic expression, interferon-inducible nature, and nuclear localization (HIN) domain family member 1 (PYHIN1), also known as IFIX, belongs to the family of pyrin proteins. This family includes structurally and functionally related mouse (e.g., p202, p203, and p204 proteins) and human (e.g., the interferon-inducible protein 16, absent in melanoma 2 protein, myeloid cell nuclear differentiation antigen, and pyrin and HIN domain family 1 or IFIX) proteins. The IFIX protein belongs to the HIN-200 family of interferon-inducible proteins that have a 200-amino acid signature motif at their C-termini. The increased expression of pyrin proteins in most cell types inhibits cell cycle control and modulates cell survival. Consistent with this role for pyrin proteins, IFIX is a potential antiviral DNA sensor that is essential for immune responses, the detection of viral DNA in the nucleus and cytoplasm, and the binding of foreign DNA via its HIN domain in a sequence non-specific manner. By promoting the ubiquitination and subsequent degradation of MDM2, IFIX acts as a tumor suppressor, thereby leading to p53/TP53 stabilization, HDAC1 regulation via the ubiquitin-proteasome pathway, and tumor-cell-specific silencing of the maspin gene. These data demonstrate that the potential molecular mechanism(s) underlying the action of the IFIX protein might be associated with the development of human diseases, such as viral infections, malignant tumors, and autoimmune diseases. This review summarizes the current insights into IFIX functions and how its regulation affects the outcomes of various human diseases.
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Affiliation(s)
- Shan Wang
- Department of Oral Pathology, Hospital of Stomatology, The First Affiliated Hospital, Harbin Medical University, Harbin, 150001, People's Republic of China.
| | - Jie Bai
- Department of Ophthalmology, The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, 322000, People's Republic of China.
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16
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Bianco PR. The mechanism of action of the SSB interactome reveals it is the first OB-fold family of genome guardians in prokaryotes. Protein Sci 2021; 30:1757-1775. [PMID: 34089559 PMCID: PMC8376408 DOI: 10.1002/pro.4140] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/28/2021] [Accepted: 05/28/2021] [Indexed: 12/28/2022]
Abstract
The single-stranded DNA binding protein (SSB) is essential to all aspects of DNA metabolism in bacteria. This protein performs two distinct, but closely intertwined and indispensable functions in the cell. SSB binds to single-stranded DNA (ssDNA) and at least 20 partner proteins resulting in their regulation. These partners comprise a family of genome guardians known as the SSB interactome. Essential to interactome regulation is the linker/OB-fold network of interactions. This network of interactions forms when one or more PXXP motifs in the linker of SSB bind to an OB-fold in a partner, with interactome members involved in competitive binding between the linker and ssDNA to their OB-fold. Consequently, when linker-binding occurs to an OB-fold in an interactome partner, proteins are loaded onto the DNA. When linker/OB-fold interactions occur between SSB tetramers, cooperative ssDNA-binding results, producing a multi-tetrameric complex that rapidly protects the ssDNA. Within this SSB-ssDNA complex, there is an extensive and dynamic network of linker/OB-fold interactions that involves multiple tetramers bound contiguously along the ssDNA lattice. The dynamic behavior of these tetramers which includes binding mode changes, sliding as well as DNA wrapping/unwrapping events, are likely coupled to the formation and disruption of linker/OB-fold interactions. This behavior is essential to facilitating downstream DNA processing events. As OB-folds are critical to the essence of the linker/OB-fold network of interactions, and they are found in multiple interactome partners, the SSB interactome is classified as the first family of prokaryotic, oligosaccharide/oligonucleotide binding fold (OB-fold) genome guardians.
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MESH Headings
- Amino Acid Motifs
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Binding, Competitive
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- DNA, Single-Stranded/chemistry
- DNA, Single-Stranded/genetics
- DNA, Single-Stranded/metabolism
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Escherichia coli/chemistry
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression Regulation, Bacterial
- Gene Regulatory Networks
- Genome, Bacterial
- Klebsiella pneumoniae/chemistry
- Klebsiella pneumoniae/genetics
- Klebsiella pneumoniae/metabolism
- Models, Molecular
- Oligonucleotides/chemistry
- Oligonucleotides/metabolism
- Oligosaccharides/chemistry
- Oligosaccharides/metabolism
- Protein Binding
- Protein Conformation
- Protein Interaction Mapping
- Protein Multimerization
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Affiliation(s)
- Piero R. Bianco
- Department of Pharmaceutical Sciences, College of PharmacyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
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17
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Multifunctionality of the Telomere-Capping Shelterin Complex Explained by Variations in Its Protein Composition. Cells 2021; 10:cells10071753. [PMID: 34359923 PMCID: PMC8305809 DOI: 10.3390/cells10071753] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/03/2021] [Accepted: 07/09/2021] [Indexed: 12/31/2022] Open
Abstract
Protecting telomere from the DNA damage response is essential to avoid the entry into cellular senescence and organismal aging. The progressive telomere DNA shortening in dividing somatic cells, programmed during development, leads to critically short telomeres that trigger replicative senescence and thereby contribute to aging. In several organisms, including mammals, telomeres are protected by a protein complex named Shelterin that counteract at various levels the DNA damage response at chromosome ends through the specific function of each of its subunits. The changes in Shelterin structure and function during development and aging is thus an intense area of research. Here, we review our knowledge on the existence of several Shelterin subcomplexes and the functional independence between them. This leads us to discuss the possibility that the multifunctionality of the Shelterin complex is determined by the formation of different subcomplexes whose composition may change during aging.
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18
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Par S, Vaides S, VanderVere-Carozza PS, Pawelczak KS, Stewart J, Turchi JJ. OB-Folds and Genome Maintenance: Targeting Protein-DNA Interactions for Cancer Therapy. Cancers (Basel) 2021; 13:3346. [PMID: 34283091 PMCID: PMC8269290 DOI: 10.3390/cancers13133346] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/09/2021] [Accepted: 07/01/2021] [Indexed: 12/14/2022] Open
Abstract
Genome stability and maintenance pathways along with their requisite proteins are critical for the accurate duplication of genetic material, mutation avoidance, and suppression of human diseases including cancer. Many of these proteins participate in these pathways by binding directly to DNA, and a subset employ oligonucleotide/oligosaccharide binding folds (OB-fold) to facilitate the protein-DNA interactions. OB-fold motifs allow for sequence independent binding to single-stranded DNA (ssDNA) and can serve to position specific proteins at specific DNA structures and then, via protein-protein interaction motifs, assemble the machinery to catalyze the replication, repair, or recombination of DNA. This review provides an overview of the OB-fold structural organization of some of the most relevant OB-fold containing proteins for oncology and drug discovery. We discuss their individual roles in DNA metabolism, progress toward drugging these motifs and their utility as potential cancer therapeutics. While protein-DNA interactions were initially thought to be undruggable, recent reports of success with molecules targeting OB-fold containing proteins suggest otherwise. The potential for the development of agents targeting OB-folds is in its infancy, but if successful, would expand the opportunities to impinge on genome stability and maintenance pathways for more effective cancer treatment.
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Affiliation(s)
- Sui Par
- Indiana University Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (S.P.); (S.V.)
| | - Sofia Vaides
- Indiana University Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (S.P.); (S.V.)
| | | | | | - Jason Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA;
| | - John J. Turchi
- Indiana University Comprehensive Cancer Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (S.P.); (S.V.)
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- NERx Biosciences, Indianapolis, IN 46202, USA;
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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19
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Kivanc D, Dasdemir S. The relationship between defects in DNA repair genes and autoinflammatory diseases. Rheumatol Int 2021; 42:1-13. [PMID: 34091703 DOI: 10.1007/s00296-021-04906-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 05/29/2021] [Indexed: 01/11/2023]
Abstract
Tissue inflammation and damage with the abnormal and overactivation of innate immune system results with the development of a hereditary disease group of autoinflammatory diseases. Multiple numbers of DNA damage develop with the continuous exposure to endogenous and exogenous genotoxic effects, and these damages are repaired through the DNA damage response governed by the genes involved in the DNA repair mechanisms, and proteins of these genes. Studies showed that DNA damage might trigger the innate immune response through nuclear DNA accumulation in the cytoplasm, and through chronic DNA damage response which signals itself and/or by micronucleus. The aim of the present review is to identify the effect of mutation that occurred in DNA repair genes on development of DNA damage response and autoinflammatory diseases.
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Affiliation(s)
- Demet Kivanc
- Department of Medical Biology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Selcuk Dasdemir
- Department of Medical Biology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
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20
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Lin M, Malik FK, Guo JT. A comparative study of protein-ssDNA interactions. NAR Genom Bioinform 2021; 3:lqab006. [PMID: 33655206 PMCID: PMC7902235 DOI: 10.1093/nargab/lqab006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/24/2020] [Accepted: 01/26/2021] [Indexed: 12/18/2022] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) play crucial roles in DNA replication, recombination and repair, and serve as key players in the maintenance of genomic stability. While a number of SSBs bind single-stranded DNA (ssDNA) non-specifically, the others recognize and bind specific ssDNA sequences. The mechanisms underlying this binding discrepancy, however, are largely unknown. Here, we present a comparative study of protein-ssDNA interactions by annotating specific and non-specific SSBs and comparing structural features such as DNA-binding propensities and secondary structure types of residues in SSB-ssDNA interactions, protein-ssDNA hydrogen bonding and π-π interactions between specific and non-specific SSBs. Our results suggest that protein side chain-DNA base hydrogen bonds are the major contributors to protein-ssDNA binding specificity, while π-π interactions may mainly contribute to binding affinity. We also found the enrichment of aspartate in the specific SSBs, a key feature in specific protein-double-stranded DNA (dsDNA) interactions as reported in our previous study. In addition, no significant differences between specific and non-specific groups with respect of conformational changes upon ssDNA binding were found, suggesting that the flexibility of SSBs plays a lesser role than that of dsDNA-binding proteins in conferring binding specificity.
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Affiliation(s)
- Maoxuan Lin
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Fareeha K Malik
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, Charlotte, NC 28223, USA
- Research Center of Modeling and Simulation, National University of Science and Technology, Islamabad, 44000, Pakistan
| | - Jun-tao Guo
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, Charlotte, NC 28223, USA
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21
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Oliveira MT, Ciesielski GL. The Essential, Ubiquitous Single-Stranded DNA-Binding Proteins. Methods Mol Biol 2021; 2281:1-21. [PMID: 33847949 DOI: 10.1007/978-1-0716-1290-3_1] [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] [Indexed: 02/07/2023]
Abstract
Maintenance of genomes is fundamental for all living organisms. The diverse processes related to genome maintenance entail the management of various intermediate structures, which may be deleterious if unresolved. The most frequent intermediate structures that result from the melting of the DNA duplex are single-stranded (ss) DNA stretches. These are thermodynamically less stable and can spontaneously fold into secondary structures, which may obstruct a variety of genome processes. In addition, ssDNA is more prone to breaking, which may lead to the formation of deletions or DNA degradation. Single-stranded DNA-binding proteins (SSBs) bind and stabilize ssDNA, preventing the abovementioned deleterious consequences and recruiting the appropriate machinery to resolve that intermediate molecule. They are present in all forms of life and are essential for their viability, with very few exceptions. Here we present an introductory chapter to a volume of the Methods in Molecular Biology dedicated to SSBs, in which we provide a general description of SSBs from various taxa.
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Affiliation(s)
- Marcos T Oliveira
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista "Júlio de Mesquita Filho", Jaboticabal, SP, Brazil
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22
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Caldwell CC, Spies M. Dynamic elements of replication protein A at the crossroads of DNA replication, recombination, and repair. Crit Rev Biochem Mol Biol 2020; 55:482-507. [PMID: 32856505 PMCID: PMC7821911 DOI: 10.1080/10409238.2020.1813070] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/18/2020] [Accepted: 08/18/2020] [Indexed: 01/19/2023]
Abstract
The heterotrimeric eukaryotic Replication protein A (RPA) is a master regulator of numerous DNA metabolic processes. For a long time, it has been viewed as an inert protector of ssDNA and a platform for assembly of various genome maintenance and signaling machines. Later, the modular organization of the RPA DNA binding domains suggested a possibility for dynamic interaction with ssDNA. This modular organization has inspired several models for the RPA-ssDNA interaction that aimed to explain how RPA, the high-affinity ssDNA binding protein, is replaced by the downstream players in DNA replication, recombination, and repair that bind ssDNA with much lower affinity. Recent studies, and in particular single-molecule observations of RPA-ssDNA interactions, led to the development of a new model for the ssDNA handoff from RPA to a specific downstream factor where not only stability and structural rearrangements but also RPA conformational dynamics guide the ssDNA handoff. Here we will review the current knowledge of the RPA structure, its dynamic interaction with ssDNA, and how RPA conformational dynamics may be influenced by posttranslational modification and proteins that interact with RPA, as well as how RPA dynamics may be harnessed in cellular decision making.
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Affiliation(s)
- Colleen C. Caldwell
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Maria Spies
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
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23
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Nguyen DD, Kim EY, Sang PB, Chai W. Roles of OB-Fold Proteins in Replication Stress. Front Cell Dev Biol 2020; 8:574466. [PMID: 33043007 PMCID: PMC7517361 DOI: 10.3389/fcell.2020.574466] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/25/2020] [Indexed: 12/20/2022] Open
Abstract
Accurate DNA replication is essential for maintaining genome stability. However, this stability becomes vulnerable when replication fork progression is stalled or slowed - a condition known as replication stress. Prolonged fork stalling can cause DNA damage, leading to genome instabilities. Thus, cells have developed several pathways and a complex set of proteins to overcome the challenge at stalled replication forks. Oligonucleotide/oligosaccharide binding (OB)-fold containing proteins are a group of proteins that play a crucial role in fork protection and fork restart. These proteins bind to single-stranded DNA with high affinity and prevent premature annealing and unwanted nuclease digestion. Among these OB-fold containing proteins, the best studied in eukaryotic cells are replication protein A (RPA) and breast cancer susceptibility protein 2 (BRCA2). Recently, another RPA-like protein complex CTC1-STN1-TEN1 (CST) complex has been found to counter replication perturbation. In this review, we discuss the latest findings on how these OB-fold containing proteins (RPA, BRCA2, CST) cooperate to safeguard DNA replication and maintain genome stability.
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Affiliation(s)
| | | | | | - Weihang Chai
- Department of Cancer Biology, Cardinal Bernardin Cancer Center, Loyola University Chicago Stritch School of Medicine, Maywood, IL, United States
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24
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Ding W, Tan HY, Zhang JX, Wilczek LA, Hsieh KR, Mulkin JA, Bianco PR. The mechanism of Single strand binding protein-RecG binding: Implications for SSB interactome function. Protein Sci 2020; 29:1211-1227. [PMID: 32196797 PMCID: PMC7184773 DOI: 10.1002/pro.3855] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/11/2020] [Accepted: 03/13/2020] [Indexed: 01/10/2023]
Abstract
The Escherichia coli single-strand DNA binding protein (SSB) is essential to viability where it functions to regulate SSB interactome function. Here it binds to single-stranded DNA and to target proteins that comprise the interactome. The region of SSB that links these two essential protein functions is the intrinsically disordered linker. Key to linker function is the presence of three, conserved PXXP motifs that mediate binding to oligosaccharide-oligonucleotide binding folds (OB-fold) present in SSB and its interactome partners. Not surprisingly, partner OB-fold deletions eliminate SSB binding. Furthermore, single point mutations in either the PXXP motifs or, in the RecG OB-fold, obliterate SSB binding. The data also demonstrate that, and in contrast to the view currently held in the field, the C-terminal acidic tip of SSB is not required for interactome partner binding. Instead, we propose the tip has two roles. First, and consistent with the proposal of Dixon, to regulate the structure of the C-terminal domain in a biologically active conformation that prevents linkers from binding to SSB OB-folds until this interaction is required. Second, as a secondary binding domain. Finally, as OB-folds are present in SSB and many of its partners, we present the SSB interactome as the first family of OB-fold genome guardians identified in prokaryotes.
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Affiliation(s)
- Wenfei Ding
- Center for Single Molecule BiophysicsUniversity at BuffaloBuffaloNew YorkUnited States
- Department of BiochemistryUniversity at BuffaloBuffaloNew YorkUnited States
| | - Hui Yin Tan
- Center for Single Molecule BiophysicsUniversity at BuffaloBuffaloNew YorkUnited States
- Present address:
Department of Chemistry and BiochemistryUniversity of Notre DameSouth BendIndianaUnited States
| | - Jia Xiang Zhang
- Department of BiochemistryUniversity at BuffaloBuffaloNew YorkUnited States
| | - Luke A. Wilczek
- Center for Single Molecule BiophysicsUniversity at BuffaloBuffaloNew YorkUnited States
- Department of BiochemistryUniversity at BuffaloBuffaloNew YorkUnited States
- Present address:
Department of ChemistryBrown UniversityProvidenceRhode IslandUnited States
| | - Karin R. Hsieh
- Center for Single Molecule BiophysicsUniversity at BuffaloBuffaloNew YorkUnited States
| | - Jeffrey A. Mulkin
- Center for Single Molecule BiophysicsUniversity at BuffaloBuffaloNew YorkUnited States
| | - Piero R. Bianco
- Center for Single Molecule BiophysicsUniversity at BuffaloBuffaloNew YorkUnited States
- Department of BiochemistryUniversity at BuffaloBuffaloNew YorkUnited States
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25
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Zhang Y, Yu C. Distinct expression and prognostic values of the replication protein A family in gastric cancer. Oncol Lett 2020; 19:1831-1841. [PMID: 32194677 PMCID: PMC7038973 DOI: 10.3892/ol.2020.11253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 09/26/2019] [Indexed: 12/21/2022] Open
Abstract
The replication protein A (RPA)1-4 family are single-stranded DNA-binding proteins that are essential components of DNA replication, repair and recombination, and cell cycle regulation. The present study aimed to evaluate the prognostic value of the RPA family members in patients with gastric cancer (GC), using datasets retrieved from the Oncomine public database. Datasets were retrieved for the purpose of comparing the RPA expression levels between GC and normal tissues. Additionally, Kaplan-Meier analysis was used to compare the overall survival (OS) times of GC patients that expressed different levels of RPA proteins. RPA1, 2, and 3 expression levels were all significantly upregulated in gastric intestinal-type, diffuse gastric, and gastric mixed adenocarcinomas, compared with those in normal mucosal tissues. Moreover, high mRNA expression levels of RPA3 and 4 predicted poorer OS times in all GCs, as well as patients with human epidermal growth factor receptor 2-negative and -positive GC. The high-risk group, separated by RPA signature, showed a poorer outcome than the low-risk group. RPA3 was the most strongly correlated with CD4+ T-cell levels. In conclusion, RPAs are novel prognostic indicators in GC, and can also predict the features of immunological diseases. Future experimental investigation into the roles of RPAs concerning the pathogenesis and development of GC may provide a novel biomarker or therapeutic target, improving the prognosis of patients with GC.
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Affiliation(s)
- Yujie Zhang
- Department of Gastrointestinal Surgery, Tongji Hospital, Tongji Medical College in Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Chaoran Yu
- Fudan University Shanghai Cancer Center, Fudan University, Shanghai 200025, P.R. China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200025, P.R. China
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26
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Hustedt N, Saito Y, Zimmermann M, Álvarez-Quilón A, Setiaputra D, Adam S, McEwan A, Yuan JY, Olivieri M, Zhao Y, Kanemaki MT, Jurisicova A, Durocher D. Control of homologous recombination by the HROB-MCM8-MCM9 pathway. Genes Dev 2019; 33:1397-1415. [PMID: 31467087 PMCID: PMC6771392 DOI: 10.1101/gad.329508.119] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/08/2019] [Indexed: 12/17/2022]
Abstract
In this study, Hustedt et al. use CRISPR-based genetic screens to build a clear picture of the postsynaptic steps of homologous recombination in mammalian cells. They report the identification of C17orf53/HROB, a factor required for cell survival after exposure to a variety of replication stress-inducing genotoxins and for the resolution but not formation of Rad51 foci. DNA repair by homologous recombination (HR) is essential for genomic integrity, tumor suppression, and the formation of gametes. HR uses DNA synthesis to repair lesions such as DNA double-strand breaks and stalled DNA replication forks, but despite having a good understanding of the steps leading to homology search and strand invasion, we know much less of the mechanisms that establish recombination-associated DNA polymerization. Here, we report that C17orf53/HROB is an OB-fold-containing factor involved in HR that acts by recruiting the MCM8–MCM9 helicase to sites of DNA damage to promote DNA synthesis. Mice with targeted mutations in Hrob are infertile due to depletion of germ cells and display phenotypes consistent with a prophase I meiotic arrest. The HROB–MCM8–MCM9 pathway acts redundantly with the HELQ helicase, and cells lacking both HROB and HELQ have severely impaired HR, suggesting that they underpin two major routes for the completion of HR downstream from RAD51. The function of HROB in HR is reminiscent of that of gp59, which acts as the replicative helicase loader during bacteriophage T4 recombination-dependent DNA replication. We therefore propose that the loading of MCM8–MCM9 by HROB may similarly be a key step in the establishment of mammalian recombination-associated DNA synthesis.
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Affiliation(s)
- Nicole Hustedt
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Yuichiro Saito
- Department of Chromosome Science, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Michal Zimmermann
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | | | - Dheva Setiaputra
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Salomé Adam
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Andrea McEwan
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Jing Yi Yuan
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Michele Olivieri
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Yichao Zhao
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
| | - Andrea Jurisicova
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Department of Obstetrics and Gynecology, University of Toronto, Toronto, Ontario M5G 0D8, Canada
| | - Daniel Durocher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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27
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Wang QM, Yang YT, Wang YR, Gao B, Xi XG, Hou XM. Human replication protein A induces dynamic changes in single-stranded DNA and RNA structures. J Biol Chem 2019; 294:13915-13927. [PMID: 31350334 DOI: 10.1074/jbc.ra119.009737] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 07/25/2019] [Indexed: 01/05/2023] Open
Abstract
Replication protein A (RPA) is the major eukaryotic ssDNA-binding protein and has essential roles in genome maintenance. RPA binds to ssDNA through multiple modes, and recent studies have suggested that the RPA-ssDNA interaction is dynamic. However, how RPA alternates between different binding modes and modifies ssDNA structures in this dynamic interaction remains unknown. Here, we used single-molecule FRET to systematically investigate the interaction between human RPA and ssDNA. We show that RPA can adopt different types of binding complexes with ssDNAs of different lengths, leading to the straightening or bending of the ssDNAs, depending on both the length and structure of the ssDNA substrate and the RPA concentration. Importantly, we noted that some of the complexes are highly dynamic, whereas others appear relatively static. On the basis of the above observations, we propose a model explaining how RPA dynamically engages with ssDNA. Of note, fluorescence anisotropy indicated that RPA can also associate with RNA but with a lower binding affinity than with ssDNA. At the single-molecule level, we observed that RPA is undergoing rapid and repetitive associations with and dissociation from the RNA. This study may provide new insights into the rich dynamics of RPA binding to ssDNA and RNA.
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Affiliation(s)
- Qing-Man Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yan-Tao Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yi-Ran Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Bo Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xu-Guang Xi
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China.,Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure de Cachan, CNRS, 61 Avenue du Président Wilson, 94235 Cachan, France
| | - Xi-Miao Hou
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
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28
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Setiaputra D, Durocher D. Shieldin - the protector of DNA ends. EMBO Rep 2019; 20:embr.201847560. [PMID: 30948458 DOI: 10.15252/embr.201847560] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 01/26/2019] [Accepted: 02/06/2019] [Indexed: 12/29/2022] Open
Abstract
DNA double-strand breaks are a threat to genome integrity and cell viability. The nucleolytic processing of broken DNA ends plays a central role in dictating the repair processes that will mend these lesions. Usually, DNA end resection promotes repair by homologous recombination, whereas minimally processed ends are repaired by non-homologous end joining. Important in this process is the chromatin-binding protein 53BP1, which inhibits DNA end resection. How 53BP1 shields DNA ends from nucleases has been an enduring mystery. The recent discovery of shieldin, a four-subunit protein complex with single-stranded DNA-binding activity, illuminated a strong candidate for the ultimate effector of 53BP1-dependent end protection. Shieldin consists of REV7, a known 53BP1-pathway component, and three hitherto uncharacterized proteins: C20orf196 (SHLD1), FAM35A (SHLD2), and CTC-534A2.2 (SHLD3). Shieldin promotes many 53BP1-associated activities, such as the protection of DNA ends, non-homologous end joining, and immunoglobulin class switching. This review summarizes the identification of shieldin and the various models of shieldin action and highlights some outstanding questions requiring answers to gain a full molecular understanding of shieldin function.
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Affiliation(s)
- Dheva Setiaputra
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
| | - Daniel Durocher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada .,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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29
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Youkharibache P, Veretnik S, Li Q, Stanek KA, Mura C, Bourne PE. The Small β-Barrel Domain: A Survey-Based Structural Analysis. Structure 2018; 27:6-26. [PMID: 30393050 DOI: 10.1016/j.str.2018.09.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 06/12/2018] [Accepted: 09/19/2018] [Indexed: 11/27/2022]
Abstract
The small β-barrel (SBB) is an ancient protein structural domain characterized by extremes: it features a broad range of structural varieties, a deeply intricate evolutionary history, and it is associated with a bewildering array of cellular pathways. Here, we present a thorough, survey-based analysis of the structural properties of SBBs. We first consider the defining properties of the SBB, including various systems of nomenclature used to describe it, and we introduce the unifying concept of an "urfold." To begin elucidating how vast functional diversity can be achieved by a relatively simple domain, we explore the anatomy of the SBB and its representative structural variants. Many SBB proteins assemble into cyclic oligomers as the biologically functional units; these oligomers often bind RNA, and typically exhibit great quaternary structural plasticity (homomeric and heteromeric rings, variable subunit stoichiometries, etc.). We conclude with three themes that emerge from the rich structure ↔ function versatility of the SBB.
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Affiliation(s)
- Philippe Youkharibache
- National Center for Biotechnology Information, The National Library of Medicine, The National Institutes of Health, Bethesda, MD 20894, USA
| | - Stella Veretnik
- National Center for Biotechnology Information, The National Library of Medicine, The National Institutes of Health, Bethesda, MD 20894, USA.
| | - Qingliang Li
- National Center for Biotechnology Information, The National Library of Medicine, The National Institutes of Health, Bethesda, MD 20894, USA
| | - Kimberly A Stanek
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Cameron Mura
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA.
| | - Philip E Bourne
- National Center for Biotechnology Information, The National Library of Medicine, The National Institutes of Health, Bethesda, MD 20894, USA.
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30
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In silico identification of inhibitors targeting N-Terminal domain of human Replication Protein A. J Mol Graph Model 2018; 86:149-159. [PMID: 30366191 DOI: 10.1016/j.jmgm.2018.10.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 12/29/2022]
Abstract
Replication Protein A (RPA) mediates DNA Damage Response (DDR) pathways through protein-protein interactions (PPIs). Targeting the PPIs formed between RPA and other DNA Damage Response (DDR) mediators has become an intriguing area of research for cancer drug discovery. A number of studies applied different methods ranging from high throughput screening approaches to fragment-based drug design tools to discover RPA inhibitors. Although these methods are robust, virtual screening approaches may be allocated as an alternative to such experimental methods, especially for screening of large libraries. Here we report the comprehensive screening of the large database, ZINC15 composed of ∼750 M compounds and the comparison of the identified ligands with the previously known inhibitors by means of binding affinity and drug-likeness. Initially, a ligand library sharing similarity with a promising inhibitor of the N-terminal domain of the RPA70 subunit (RPA70N) was generated by screening of the ZINC15 library. 46,999 ligands were collected and screened by LeDock which produced a satisfactory correlation with the experimental values (R2 = 0.77). 10 of the top-scoring ligands in LeDock were directly progressed to molecular dynamics (MD) simulations, while 10 additional ligands were also selected based on their LeDock scores and the presence of a functional group that could interact with the key amino acids in the RPA70N cleft. MD simulations were used to predict the binding free energy of the ligands by the MM-PBSA method which produced a high level of agreement with the experiments (R2 = 0.85). Binding free energy predictions pointed out 2 ligands with higher binding affinity than any of the reference inhibitors. Particularly the ligand ZINC000753854163 exhibited superior drug-likeness features than any of the known inhibitors. Overall, this study reports ZINC000753854163 as a possible inhibitor of RPA70N, reflecting its possible use in RPA70N targeted cancer therapy.
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31
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Single-stranded telomere-binding protein employs a dual rheostat for binding affinity and specificity that drives function. Proc Natl Acad Sci U S A 2018; 115:10315-10320. [PMID: 30249661 PMCID: PMC6187146 DOI: 10.1073/pnas.1722147115] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Proteins that bind nucleic acids are frequently categorized as being either specific or nonspecific, with interfaces to match that activity. In this study, we have found that a telomere-binding protein exhibits a degree of specificity for ssDNA that is finely tuned for its function, which includes specificity for G-rich sequences with some tolerance for substitution. Mutations of the protein that dramatically impact its affinity for single-stranded telomeric DNA are lethal, as expected; however, mutations that alter specificity also impact biological function. Unexpectedly, we found mutations that make the protein more specific are also deleterious, suggesting that specificity and nonspecificity in nucleic acid recognition may be achieved through more nuanced mechanisms than currently recognized. ssDNA, which is involved in numerous aspects of chromosome biology, is managed by a suite of proteins with tailored activities. The majority of these proteins bind ssDNA indiscriminately, exhibiting little apparent sequence preference. However, there are several notable exceptions, including the Saccharomyces cerevisiae Cdc13 protein, which is vital for yeast telomere maintenance. Cdc13 is one of the tightest known binders of ssDNA and is specific for G-rich telomeric sequences. To investigate how these two different biochemical features, affinity and specificity, contribute to function, we created an unbiased panel of alanine mutations across the Cdc13 DNA-binding interface, including several aromatic amino acids that play critical roles in binding activity. A subset of mutant proteins exhibited significant loss in affinity in vitro that, as expected, conferred a profound loss of viability in vivo. Unexpectedly, a second category of mutant proteins displayed an increase in specificity, manifested as an inability to accommodate changes in ssDNA sequence. Yeast strains with specificity-enhanced mutations displayed a gradient of viability in vivo that paralleled the loss in sequence tolerance in vitro, arguing that binding specificity can be fine-tuned to ensure optimal function. We propose that DNA binding by Cdc13 employs a highly cooperative interface whereby sequence diversity is accommodated through plastic binding modes. This suggests that sequence specificity is not a binary choice but rather is a continuum. Even in proteins that are thought to be specific nucleic acid binders, sequence tolerance through the utilization of multiple binding modes may be a broader phenomenon than previously appreciated.
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32
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Lloyd NR, Wuttke DS. Discrimination against RNA Backbones by a ssDNA Binding Protein. Structure 2018; 26:722-733.e2. [PMID: 29681468 DOI: 10.1016/j.str.2018.03.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 01/10/2018] [Accepted: 03/27/2018] [Indexed: 11/18/2022]
Abstract
Pot1 is the shelterin component responsible for the protection of the single-stranded DNA (ssDNA) overhang at telomeres in nearly all eukaryotic organisms. The C-terminal domain of the DNA-binding domain, Pot1pC, exhibits non-specific ssDNA recognition, achieved through thermodynamically equivalent alternative binding conformations. Given this flexibility, it is unclear how specificity for ssDNA over RNA, an activity required for biological function, is achieved. Examination of the ribose-position specificity of Pot1pC shows that ssDNA specificity is additive but not uniformly distributed across the ligand. High-resolution structures of several Pot1pC complexes with RNA-DNA chimeric ligands reveal Pot1pC discriminates against RNA by utilizing non-compensatory binding modes that feature significant rearrangement of the binding interface. These alternative conformations, accessed through both ligand and protein flexibility, recover much, but not all, of the binding energy, leading to the observed reduction in affinities. These findings suggest that intermolecular interfaces are remarkably sophisticated in their tuning of specificity toward flexible ligands.
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Affiliation(s)
- Neil R Lloyd
- Department of Chemistry and Biochemistry, University of Colorado, UCB 596, Boulder, CO 80309-0596, USA
| | - Deborah S Wuttke
- Department of Chemistry and Biochemistry, University of Colorado, UCB 596, Boulder, CO 80309-0596, USA.
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33
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Antony E, Lohman TM. Dynamics of E. coli single stranded DNA binding (SSB) protein-DNA complexes. Semin Cell Dev Biol 2018; 86:102-111. [PMID: 29588158 DOI: 10.1016/j.semcdb.2018.03.017] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/22/2018] [Accepted: 03/23/2018] [Indexed: 01/25/2023]
Abstract
Single stranded DNA binding proteins (SSB) are essential to the cell as they stabilize transiently open single stranded DNA (ssDNA) intermediates, recruit appropriate DNA metabolism proteins, and coordinate fundamental processes such as replication, repair and recombination. Escherichia coli single stranded DNA binding protein (EcSSB) has long served as the prototype for the study of SSB function. The structure, functions, and DNA binding properties of EcSSB are well established: The protein is a stable homotetramer with each subunit possessing an N-terminal DNA binding core, a C-terminal protein-protein interaction tail, and an intervening intrinsically disordered linker (IDL). EcSSB wraps ssDNA in multiple DNA binding modes and can diffuse along DNA to remove secondary structures and remodel other protein-DNA complexes. This review provides an update on these features based on recent findings, with special emphasis on the functional and mechanistic relevance of the IDL and DNA binding modes.
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Affiliation(s)
- Edwin Antony
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA.
| | - Timothy M Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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34
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Maffeo C, Aksimentiev A. Molecular mechanism of DNA association with single-stranded DNA binding protein. Nucleic Acids Res 2017; 45:12125-12139. [PMID: 29059392 PMCID: PMC5716091 DOI: 10.1093/nar/gkx917] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/28/2017] [Indexed: 01/10/2023] Open
Abstract
During DNA replication, the single-stranded DNA binding protein (SSB) wraps single-stranded DNA (ssDNA) with high affinity to protect it from degradation and prevent secondary structure formation. Although SSB binds ssDNA tightly, it can be repositioned along ssDNA to follow the advancement of the replication fork. Using all-atom molecular dynamics simulations, we characterized the molecular mechanism of ssDNA association with SSB. Placed in solution, ssDNA–SSB assemblies were observed to change their structure spontaneously; such structural changes were suppressed in the crystallographic environment. Repeat simulations of the SSB–ssDNA complex under mechanical tension revealed a multitude of possible pathways for ssDNA to come off SSB punctuated by prolonged arrests at reproducible sites at the SSB surface. Ensemble simulations of spontaneous association of short ssDNA fragments with SSB detailed a three-dimensional map of local affinity to DNA; the equilibrium amount of ssDNA bound to SSB was found to depend on the electrolyte concentration but not on the presence of the acidic tips of the SSB tails. Spontaneous formation of ssDNA bulges and their diffusive motion along SSB surface was directly observed in multiple 10-µs-long simulations. Such reptation-like motion was confined by DNA binding to high-affinity spots, suggesting a two-step mechanism for SSB diffusion.
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Affiliation(s)
- Christopher Maffeo
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 W Green St, Urbana, IL 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Ave, Urbana, IL 61801, USA.,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 1205 W Clark St, Urbana, IL 61801, USA
| | - Aleksei Aksimentiev
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 W Green St, Urbana, IL 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Ave, Urbana, IL 61801, USA.,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 1205 W Clark St, Urbana, IL 61801, USA.,Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, 1110 W Green St, Urbana, IL 61801, USA
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35
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Plumridge A, Meisburger SP, Andresen K, Pollack L. The impact of base stacking on the conformations and electrostatics of single-stranded DNA. Nucleic Acids Res 2017; 45:3932-3943. [PMID: 28334825 PMCID: PMC5397193 DOI: 10.1093/nar/gkx140] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 02/17/2017] [Indexed: 12/17/2022] Open
Abstract
Single-stranded DNA (ssDNA) is notable for its interactions with ssDNA binding proteins (SSBs) during fundamentally important biological processes including DNA repair and replication. Previous work has begun to characterize the conformational and electrostatic properties of ssDNA in association with SSBs. However, the conformational distributions of free ssDNA have been difficult to determine. To capture the vast array of ssDNA conformations in solution, we pair small angle X-ray scattering with novel ensemble fitting methods, obtaining key parameters such as the size, shape and stacking character of strands with different sequences. Complementary ion counting measurements using inductively coupled plasma atomic emission spectroscopy are employed to determine the composition of the ion atmosphere at physiological ionic strength. Applying this combined approach to poly dA and poly dT, we find that the global properties of these sequences are very similar, despite having vastly different propensities for single-stranded helical stacking. These results suggest that a relatively simple mechanism for the binding of ssDNA to non-specific SSBs may be at play, which explains the disparity in binding affinities observed for these systems.
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Affiliation(s)
- Alex Plumridge
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
| | | | - Kurt Andresen
- Department of Physics, Gettysburg College, Gettysburg, PA 17325, USA
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
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36
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Jarillo J, Morín JA, Beltrán-Heredia E, Villaluenga JPG, Ibarra B, Cao FJ. Mechanics, thermodynamics, and kinetics of ligand binding to biopolymers. PLoS One 2017; 12:e0174830. [PMID: 28380044 PMCID: PMC5381885 DOI: 10.1371/journal.pone.0174830] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Accepted: 03/15/2017] [Indexed: 01/20/2023] Open
Abstract
Ligands binding to polymers regulate polymer functions by changing their physical and chemical properties. This ligand regulation plays a key role in many biological processes. We propose here a model to explain the mechanical, thermodynamic, and kinetic properties of the process of binding of small ligands to long biopolymers. These properties can now be measured at the single molecule level using force spectroscopy techniques. Our model performs an effective decomposition of the ligand-polymer system on its covered and uncovered regions, showing that the elastic properties of the ligand-polymer depend explicitly on the ligand coverage of the polymer (i.e., the fraction of the polymer covered by the ligand). The equilibrium coverage that minimizes the free energy of the ligand-polymer system is computed as a function of the applied force. We show how ligands tune the mechanical properties of a polymer, in particular its length and stiffness, in a force dependent manner. In addition, it is shown how ligand binding can be regulated applying mechanical tension on the polymer. Moreover, the binding kinetics study shows that, in the case where the ligand binds and organizes the polymer in different modes, the binding process can present transient shortening or lengthening of the polymer, caused by changes in the relative coverage by the different ligand modes. Our model will be useful to understand ligand-binding regulation of biological processes, such as the metabolism of nucleic acid. In particular, this model allows estimating the coverage fraction and the ligand mode characteristics from the force extension curves of a ligand-polymer system.
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Affiliation(s)
- Javier Jarillo
- Departamento de Física Atómica, Molecular y Nuclear. Facultad de Ciencias Físicas. Universidad Complutense de Madrid. Pza. de las Ciencias, 1. Madrid. Spain
| | - José A. Morín
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit ‘Unidad de Nanobiotecnología’, Madrid, Spain
| | - Elena Beltrán-Heredia
- Departamento de Física Atómica, Molecular y Nuclear. Facultad de Ciencias Físicas. Universidad Complutense de Madrid. Pza. de las Ciencias, 1. Madrid. Spain
| | - Juan P. G. Villaluenga
- Departamento de Física Aplicada I. Facultad de Ciencias Físicas. Universidad Complutense de Madrid. Pza. de las Ciencias, 1. Madrid. Spain
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit ‘Unidad de Nanobiotecnología’, Madrid, Spain
| | - Francisco J. Cao
- Departamento de Física Atómica, Molecular y Nuclear. Facultad de Ciencias Físicas. Universidad Complutense de Madrid. Pza. de las Ciencias, 1. Madrid. Spain
- * E-mail:
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37
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Krasikova YS, Rechkunova NI, Lavrik OI. Replication protein A as a major eukaryotic single-stranded DNA-binding protein and its role in DNA repair. Mol Biol 2016. [DOI: 10.1134/s0026893316030080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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38
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Stewart AL, Lorts AR, Seal EL, Takas NJ, Fortenberry RC. The role of sodium ions in the solubility of peptides. Struct Chem 2016. [DOI: 10.1007/s11224-016-0825-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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39
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Chen R, Subramanyam S, Elcock AH, Spies M, Wold MS. Dynamic binding of replication protein a is required for DNA repair. Nucleic Acids Res 2016; 44:5758-72. [PMID: 27131385 PMCID: PMC4937323 DOI: 10.1093/nar/gkw339] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 04/15/2016] [Indexed: 12/14/2022] Open
Abstract
Replication protein A (RPA), the major eukaryotic single-stranded DNA (ssDNA) binding protein, is essential for replication, repair and recombination. High-affinity ssDNA-binding by RPA depends on two DNA binding domains in the large subunit of RPA. Mutation of the evolutionarily conserved aromatic residues in these two domains results in a separation-of-function phenotype: aromatic residue mutants support DNA replication but are defective in DNA repair. We used biochemical and single-molecule analyses, and Brownian Dynamics simulations to determine the molecular basis of this phenotype. Our studies demonstrated that RPA binds to ssDNA in at least two modes characterized by different dissociation kinetics. We also showed that the aromatic residues contribute to the formation of the longer-lived state, are required for stable binding to short ssDNA regions and are needed for RPA melting of partially duplex DNA structures. We conclude that stable binding and/or the melting of secondary DNA structures by RPA is required for DNA repair, including RAD51 mediated DNA strand exchange, but is dispensable for DNA replication. It is likely that the binding modes are in equilibrium and reflect dynamics in the RPA-DNA complex. This suggests that dynamic binding of RPA to DNA is necessary for different cellular functions.
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Affiliation(s)
- Ran Chen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Shyamal Subramanyam
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Adrian H Elcock
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Maria Spies
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Marc S Wold
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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Baker JA, Simkovic F, Taylor HMC, Rigden DJ. Potential DNA binding and nuclease functions of ComEC domains characterized in silico. Proteins 2016; 84:1431-42. [PMID: 27318187 PMCID: PMC5031224 DOI: 10.1002/prot.25088] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/25/2016] [Accepted: 06/13/2016] [Indexed: 12/15/2022]
Abstract
Bacterial competence, which can be natural or induced, allows the uptake of exogenous double stranded DNA (dsDNA) into a competent bacterium. This process is known as transformation. A multiprotein assembly binds and processes the dsDNA to import one strand and degrade another yet the underlying molecular mechanisms are relatively poorly understood. Here distant relationships of domains in Competence protein EC (ComEC) of Bacillus subtilis (Uniprot: P39695) were characterized. DNA-protein interactions were investigated in silico by analyzing models for structural conservation, surface electrostatics and structure-based DNA binding propensity; and by data-driven macromolecular docking of DNA to models. Our findings suggest that the DUF4131 domain contains a cryptic DNA-binding OB fold domain and that the β-lactamase-like domain is the hitherto cryptic competence nuclease. Proteins 2016; 84:1431-1442. © 2016 The Authors Proteins: Structure, Function, and Bioinformatics Published by Wiley Periodicals, Inc.
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Affiliation(s)
- James A Baker
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, United Kingdom
| | - Felix Simkovic
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, United Kingdom
| | - Helen M C Taylor
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, United Kingdom
| | - Daniel J Rigden
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, United Kingdom.
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Wolf C, Rapp A, Berndt N, Staroske W, Schuster M, Dobrick-Mattheuer M, Kretschmer S, König N, Kurth T, Wieczorek D, Kast K, Cardoso MC, Günther C, Lee-Kirsch MA. RPA and Rad51 constitute a cell intrinsic mechanism to protect the cytosol from self DNA. Nat Commun 2016; 7:11752. [PMID: 27230542 PMCID: PMC4895045 DOI: 10.1038/ncomms11752] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 04/26/2016] [Indexed: 11/15/2022] Open
Abstract
Immune recognition of cytosolic DNA represents a central antiviral defence mechanism. Within the host, short single-stranded DNA (ssDNA) continuously arises during the repair of DNA damage induced by endogenous and environmental genotoxic stress. Here we show that short ssDNA traverses the nuclear membrane, but is drawn into the nucleus by binding to the DNA replication and repair factors RPA and Rad51. Knockdown of RPA and Rad51 enhances cytosolic leakage of ssDNA resulting in cGAS-dependent type I IFN activation. Mutations in the exonuclease TREX1 cause type I IFN-dependent autoinflammation and autoimmunity. We demonstrate that TREX1 is anchored within the outer nuclear membrane to ensure immediate degradation of ssDNA leaking into the cytosol. In TREX1-deficient fibroblasts, accumulating ssDNA causes exhaustion of RPA and Rad51 resulting in replication stress and activation of p53 and type I IFN. Thus, the ssDNA-binding capacity of RPA and Rad51 constitutes a cell intrinsic mechanism to protect the cytosol from self DNA. A central antiviral defence is immune recognition of cystolic DNA. Here the authors show that RPA and RAD51, in cooperation with TREX1, function to protect the cytosol from self-DNA.
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Affiliation(s)
- Christine Wolf
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Alexander Rapp
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Nicole Berndt
- Department of Dermatology, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Wolfgang Staroske
- Biotechnology Center, Technische Universität Dresden, 01307 Dresden, Germany
| | - Max Schuster
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Manuela Dobrick-Mattheuer
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Stefanie Kretschmer
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Nadja König
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Thomas Kurth
- Biotechnology Center, Technische Universität Dresden, 01307 Dresden, Germany.,Center for Regenerative Therapies, Technische Universität Dresden, 01307 Dresden, Germany
| | - Dagmar Wieczorek
- Institute of Human Genetics, Heinrich-Heine-University, Medical Faculty, 40225 Düsseldorf, Germany
| | - Karin Kast
- Department of Gynecology, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - M Cristina Cardoso
- Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Claudia Günther
- Department of Dermatology, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Min Ae Lee-Kirsch
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
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Nguyen HN, Zhao L, Gray CW, Gray DM, Xia T. Nucleotides sequestered at different subsite loci within DNA-binding pockets of two OB-fold single-stranded DNA-binding proteins are unstacked to different extents. Biopolymers 2016; 99:484-96. [PMID: 23616216 DOI: 10.1002/bip.22204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 01/03/2013] [Indexed: 11/07/2022]
Abstract
The gene 5 protein (g5p) encoded by the Ff strains of Escherichia coli bacteriophages is a dimeric single-stranded DNA-binding protein (SSB) that consists of two identical OB-fold (oligonucleotide/oligosaccharide-binding) motifs. Ultrafast time-resolved fluorescence measurements were carried out to investigate the effect of g5p binding on the conformation of 2-aminopurine (2AP) labels positioned between adenines or cytosines in the 16-nucleotide antiparallel tails of DNA hairpins. The measurements revealed significant changes in the conformational heterogeneity of the 2AP labels caused by g5p binding. The extent of the changes was dependent on sub-binding-site location, but generally resulted in base unstacking. When bound by g5p, the unstacked 2AP population increased from ∼ 22% to 59-67% in C-2AP-C segments and from 39% to 77% in an A-2AP-A segment. The OB-fold RPA70A domain of the human replication protein A also caused a significant amount of base unstacking at various locations within the DNA binding site as evidenced by steady-state fluorescence titration measurements using 2AP-labeled 5-mer DNAs. These solution studies support the concept that base unstacking at most of a protein's multiple sub-binding-site loci may be a feature that allows non-sequence specific OB-fold proteins to bind to single-stranded DNAs (ssDNAs) with minimal preference for particular sequences.
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Affiliation(s)
- Hieu N Nguyen
- Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75080, USA
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Abstract
This article reviews atomic force microscopy (AFM) studies of DNA structure and dynamics and protein-DNA complexes, including recent advances in the visualization of protein-DNA complexes with the use of cutting-edge, high-speed AFM. Special emphasis is given to direct nanoscale visualization of dynamics of protein-DNA complexes. In the area of DNA structure and dynamics, structural studies of local non-B conformations of DNA and the interplay of local and global DNA conformations are reviewed. The application of time-lapse AFM nanoscale imaging of DNA dynamics is illustrated by studies of Holliday junction branch migration. Structure and dynamics of protein-DNA interactions include problems related to site-specific DNA recombination, DNA replication, and DNA mismatch repair. Studies involving the structure and dynamics of chromatin are also described.
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Affiliation(s)
- Yuri L. Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025
| | - Luda S. Shlyakhtenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025
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Purification and characterization of oligonucleotide binding (OB)-fold protein from medicinal plant Tinospora cordifolia. J Chromatogr B Analyt Technol Biomed Life Sci 2015; 1008:38-44. [PMID: 26613539 DOI: 10.1016/j.jchromb.2015.11.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 11/09/2015] [Accepted: 11/12/2015] [Indexed: 12/11/2022]
Abstract
The oligonucleotide binding fold (OB-fold) is a small structural motif present in many proteins. It is originally named for its oligonucleotide or oligosaccharide binding properties. These proteins have been identified as essential for replication, recombination and repair of DNA. We have successfully purified a protein contains OB-fold from the stem of Tinospora cordifolia, a medicinal plants of north India. Stems were crushed and centrifuged, and fraction obtained at 60% ammonium sulphate was extensively dialyzed and applied to the weak anion exchange chromatography on Hi-Trap DEAE-FF in 50mM Tris-HCl buffer at pH 8.0. Eluted fractions were concentrated and applied to gel filtration column to get pure protein. We observed a single band of 20-kDa on SDS-PAGE. Finally, the protein was identified as OB-fold by MALDI-TOF. The purified OB-fold protein was characterized for its secondary structural elements using circular dichroism (CD) in the far-UV region. Generally the OB-fold has a characteristic feature as five-stranded beta-sheet coiled to form a closed beta- barrel. To estimate its chemical stability, guanidinium chloride-induced denaturation curve was followed by observing changes in the far-UV CD as a function of the denaturant concentration. Analysis of this denaturation curve gave values of 8.90±0.25kcalmol(-1) and 3.78±0.18M for ΔGD° (Gibbs free energy change at 25°C) and Cm (midpoint of denaturation), respectively. To determine heat stability parameters of OB-fold protein, differential scanning calorimetry was performed. Calorimetric values of ΔGD°, Tm (midpoint of denaturation), ΔHm (enthalpy change at Tm), and ΔCp (constant-pressure heat capacity change) are 9.05±0.27kcalmol(-1), 85.2±0,3°C, 105±4kcalmol(-1) and 1.6±0.08kcalmol(-1)K(-1). This is the first report on the isolation, purification and characterization of OB-fold protein from a medicinal plant T. cordifolia.
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Paquet N, Adams MN, Leong V, Ashton NW, Touma C, Gamsjaeger R, Cubeddu L, Beard S, Burgess JT, Bolderson E, O'Byrne KJ, Richard DJ. hSSB1 (NABP2/ OBFC2B) is required for the repair of 8-oxo-guanine by the hOGG1-mediated base excision repair pathway. Nucleic Acids Res 2015; 43:8817-29. [PMID: 26261212 PMCID: PMC4605301 DOI: 10.1093/nar/gkv790] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/22/2015] [Indexed: 01/03/2023] Open
Abstract
The maintenance of genome stability is essential to prevent loss of genetic information and the development of diseases such as cancer. One of the most common forms of damage to the genetic code is the oxidation of DNA by reactive oxygen species (ROS), of which 8-oxo-7,8-dihydro-guanine (8-oxoG) is the most frequent modification. Previous studies have established that human single-stranded DNA-binding protein 1 (hSSB1) is essential for the repair of double-stranded DNA breaks by the process of homologous recombination. Here we show that hSSB1 is also required following oxidative damage. Cells lacking hSSB1 are sensitive to oxidizing agents, have deficient ATM and p53 activation and cannot effectively repair 8-oxoGs. Furthermore, we demonstrate that hSSB1 forms a complex with the human oxo-guanine glycosylase 1 (hOGG1) and is important for hOGG1 localization to the damaged chromatin. In vitro, hSSB1 binds directly to DNA containing 8-oxoguanines and enhances hOGG1 activity. These results underpin the crucial role hSSB1 plays as a guardian of the genome.
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Affiliation(s)
- Nicolas Paquet
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Mark N Adams
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Vincent Leong
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Nicholas W Ashton
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Christine Touma
- School of Science and Health, University of Western Sydney, Penrith, NSW 2751 Australia
| | - Roland Gamsjaeger
- School of Science and Health, University of Western Sydney, Penrith, NSW 2751 Australia School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia
| | - Liza Cubeddu
- School of Science and Health, University of Western Sydney, Penrith, NSW 2751 Australia School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia
| | - Sam Beard
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Joshua T Burgess
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Emma Bolderson
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Ken J O'Byrne
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
| | - Derek J Richard
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, Woolloongabba, QLD 4102, Australia
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46
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Guo Y, Kragelund BB, White MF, Peng X. Functional Characterization of a Conserved Archaeal Viral Operon Revealing Single-Stranded DNA Binding, Annealing and Nuclease Activities. J Mol Biol 2015; 427:2179-91. [DOI: 10.1016/j.jmb.2015.03.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/17/2015] [Accepted: 03/18/2015] [Indexed: 11/15/2022]
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47
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Steinberg-Neifach O, Lue NF. Telomere DNA recognition in Saccharomycotina yeast: potential lessons for the co-evolution of ssDNA and dsDNA-binding proteins and their target sites. Front Genet 2015; 6:162. [PMID: 25983743 PMCID: PMC4416457 DOI: 10.3389/fgene.2015.00162] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/10/2015] [Indexed: 01/22/2023] Open
Abstract
In principle, alterations in the telomere repeat sequence would be expected to disrupt the protective nucleoprotein complexes that confer stability to chromosome ends, and hence relatively rare events in evolution. Indeed, numerous organisms in diverse phyla share a canonical 6 bp telomere repeat unit (5'-TTAGGG-3'/5'-CCCTAA-3'), suggesting common descent from an ancestor that carries this particular repeat. All the more remarkable, then, are the extraordinarily divergent telomere sequences that populate the Saccharomycotina subphylum of budding yeast. These sequences are distinguished from the canonical telomere repeat in being long, occasionally degenerate, and frequently non-G/C-rich. Despite the divergent telomere repeat sequences, studies to date indicate that the same families of single-strand and double-strand telomere binding proteins (i.e., the Cdc13 and Rap1 families) are responsible for telomere protection in Saccharomycotina yeast. The recognition mechanisms of the protein family members therefore offer an informative paradigm for understanding the co-evolution of DNA-binding proteins and the cognate target sequences. Existing data suggest three potential, inter-related solutions to the DNA recognition problem: (i) duplication of the recognition protein and functional modification; (ii) combinatorial recognition of target site; and (iii) flexibility of the recognition surfaces of the DNA-binding proteins to adopt alternative conformations. Evidence in support of these solutions and the relevance of these solutions to other DNA-protein regulatory systems are discussed.
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Affiliation(s)
- Olga Steinberg-Neifach
- Department of Microbiology and Immunology, W. R. Hearst Microbiology Research Center, Weill Medical College, Cornell University , New York, NY, USA ; Hostos Community College, City University of New York , Bronx, NY, USA
| | - Neal F Lue
- Department of Microbiology and Immunology, W. R. Hearst Microbiology Research Center, Weill Medical College, Cornell University , New York, NY, USA
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48
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Kar A, Kaur M, Ghosh T, Khan MM, Sharma A, Shekhar R, Varshney A, Saxena S. RPA70 depletion induces hSSB1/2-INTS3 complex to initiate ATR signaling. Nucleic Acids Res 2015; 43:4962-74. [PMID: 25916848 PMCID: PMC4446429 DOI: 10.1093/nar/gkv369] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 04/08/2015] [Indexed: 01/12/2023] Open
Abstract
The primary eukaryotic single-stranded DNA-binding protein, Replication protein A (RPA), binds to single-stranded DNA at the sites of DNA damage and recruits the apical checkpoint kinase, ATR via its partner protein, ATRIP. It has been demonstrated that absence of RPA incapacitates the ATR-mediated checkpoint response. We report that in the absence of RPA, human single-stranded DNA-binding protein 1 (hSSB1) and its partner protein INTS3 form sub-nuclear foci, associate with the ATR-ATRIP complex and recruit it to the sites of genomic stress. The ATRIP foci formed after RPA depletion are abrogated in the absence of INTS3, establishing that hSSB-INTS3 complex recruits the ATR-ATRIP checkpoint complex to the sites of genomic stress. Depletion of homologs hSSB1/2 and INTS3 in RPA-deficient cells attenuates Chk1 phosphorylation, indicating that the cells are debilitated in responding to stress. We have identified that TopBP1 and the Rad9-Rad1-Hus1 complex are essential for the alternate mode of ATR activation. In summation, we report that the single-stranded DNA-binding protein complex, hSSB1/2-INTS3 can recruit the checkpoint complex to initiate ATR signaling.
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Affiliation(s)
- Ananya Kar
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Manpreet Kaur
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Tanushree Ghosh
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Md Muntaz Khan
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Aparna Sharma
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Ritu Shekhar
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Akhil Varshney
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Sandeep Saxena
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
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49
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Mechanochemical regulations of RPA's binding to ssDNA. Sci Rep 2015; 5:9296. [PMID: 25787788 PMCID: PMC4365408 DOI: 10.1038/srep09296] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 02/24/2015] [Indexed: 11/10/2022] Open
Abstract
Replication protein A (RPA) is a ubiquitous eukaryotic single-stranded DNA (ssDNA) binding protein that serves to protect ssDNA from degradation and annealing, and as a template for recruitment of many downstream factors in virtually all DNA transactions in cell. During many of these transactions, DNA is tethered and is likely subject to force. Previous studies of RPA's binding behavior on ssDNA were conducted in the absence of force; therefore the RPA-ssDNA conformations regulated by force remain unclear. Here, using a combination of atomic force microscopy imaging and mechanical manipulation of single ssDNA tethers, we show that force mediates a switch of the RPA bound ssDNA from amorphous aggregation to a much more regular extended conformation. Further, we found an interesting non-monotonic dependence of the binding affinity on monovalent salt concentration in the presence of force. In addition, we discovered that zinc in micromolar concentrations drives ssDNA to a unique, highly stiff and more compact state. These results provide new mechanochemical insights into the influences and the mechanisms of action of RPA on large single ssDNA.
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50
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Fridlich R, Annamalai D, Roy R, Bernheim G, Powell SN. BRCA1 and BRCA2 protect against oxidative DNA damage converted into double-strand breaks during DNA replication. DNA Repair (Amst) 2015; 30:11-20. [PMID: 25836596 DOI: 10.1016/j.dnarep.2015.03.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 02/27/2015] [Accepted: 03/03/2015] [Indexed: 12/20/2022]
Abstract
BRCA1 and BRCA2 mutation carriers are predisposed to develop breast and ovarian cancers, but the reasons for this tissue specificity are unknown. Breast epithelial cells are known to contain elevated levels of oxidative DNA damage, triggered by hormonally driven growth and its effect on cell metabolism. BRCA1- or BRCA2-deficient cells were found to be more sensitive to oxidative stress, modeled by treatment with patho-physiologic concentrations of hydrogen peroxide. Hydrogen peroxide exposure leads to oxidative DNA damage induced DNA double strand breaks (DSB) in BRCA-deficient cells causing them to accumulate in S-phase. In addition, after hydrogen peroxide treatment, BRCA deficient cells showed impaired Rad51 foci which are dependent on an intact BRCA1-BRCA2 pathway. These DSB resulted in an increase in chromatid-type aberrations, which are characteristic for BRCA1 and BRCA2-deficient cells. The most common result of oxidative DNA damage induced processing of S-phase DSB is an interstitial chromatid deletion, but insertions and exchanges were also seen in BRCA deficient cells. Thus, BRCA1 and BRCA2 are essential for the repair of oxidative DNA damage repair intermediates that persist into S-phase and produce DSB. The implication is that oxidative stress plays a role in the etiology of hereditary breast cancer.
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Affiliation(s)
- Ram Fridlich
- Department of Radiation Oncology and Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, United States
| | - Devi Annamalai
- Department of Radiation Oncology and Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, United States
| | - Rohini Roy
- Department of Radiation Oncology and Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, United States
| | - Giana Bernheim
- Department of Radiation Oncology and Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, United States
| | - Simon N Powell
- Department of Radiation Oncology and Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, United States.
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