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Nautiyal A, Thakur M. Prokaryotic DNA Crossroads: Holliday Junction Formation and Resolution. ACS OMEGA 2024; 9:12515-12538. [PMID: 38524412 PMCID: PMC10956419 DOI: 10.1021/acsomega.3c09866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 02/04/2024] [Accepted: 02/09/2024] [Indexed: 03/26/2024]
Abstract
Cells are continually exposed to a multitude of internal and external stressors, which give rise to various types of DNA damage. To protect the integrity of their genetic material, cells are equipped with a repertoire of repair proteins that engage in various repair mechanisms, facilitated by intricate networks of protein-protein and protein-DNA interactions. Among these networks is the homologous recombination (HR) system, a molecular repair mechanism conserved in all three domains of life. On one hand, HR ensures high-fidelity, template-dependent DNA repair, while on the other hand, it results in the generation of combinatorial genetic variations through allelic exchange. Despite substantial progress in understanding this pathway in bacteria, yeast, and humans, several critical questions remain unanswered, including the molecular processes leading to the exchange of DNA segments, the coordination of protein binding, conformational switching during branch migration, and the resolution of Holliday Junctions (HJs). This Review delves into our current understanding of the HR pathway in bacteria, shedding light on the roles played by various proteins or their complexes at different stages of HR. In the first part of this Review, we provide a brief overview of the end resection processes and the strand-exchange reaction, offering a concise depiction of the mechanisms that culminate in the formation of HJs. In the latter half, we expound upon the alternative methods of branch migration and HJ resolution more comprehensively and holistically, considering the historical research timelines. Finally, when we consolidate our knowledge about HR within the broader context of genome replication and the emergence of resistant species, it becomes evident that the HR pathway is indispensable for the survival of bacteria in diverse ecological niches.
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Affiliation(s)
- Astha Nautiyal
- Department
of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Manoj Thakur
- Sri
Venkateswara College, Benito Juarez Road, University of Delhi, New Delhi 110021, India
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Mittal P, Sinha R, Kumar A, Singh P, Ngasainao MR, Singh A, Singh IK. Focusing on DNA Repair and Damage Tolerance Mechanisms in Mycobacterium tuberculosis: An Emerging Therapeutic Theme. Curr Top Med Chem 2020; 20:390-408. [PMID: 31924156 DOI: 10.2174/1568026620666200110114322] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 09/02/2019] [Accepted: 10/10/2019] [Indexed: 11/22/2022]
Abstract
Tuberculosis (TB) is one such disease that has become a nuisance in the world scenario and one of the most deadly diseases of the current times. The etiological agent of tuberculosis, Mycobacterium tuberculosis (M. tb) kills millions of people each year. Not only 1.7 million people worldwide are estimated to harbor M. tb in the latent form but also 5 to 15 percent of which are expected to acquire an infection during a lifetime. Though curable, a long duration of drug regimen and expense leads to low patient adherence. The emergence of multi-, extensive- and total- drug-resistant strains of M. tb further complicates the situation. Owing to high TB burden, scientists worldwide are trying to design novel therapeutics to combat this disease. Therefore, to identify new drug targets, there is a growing interest in targeting DNA repair pathways to fight this infection. Thus, this review aims to explore DNA repair and damage tolerance as an efficient target for drug development by understanding M. tb DNA repair and tolerance machinery and its regulation, its role in pathogenesis and survival, mutagenesis, and consequently, in the development of drug resistance.
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Affiliation(s)
- Pooja Mittal
- Molecular Biology Research Lab, Department of Zoology, Deshbandhu College, University of Delhi, Kalkaji, New Delhi, 110019, India
| | - Rajesh Sinha
- Molecular Biology Research Lab, Department of Zoology, Deshbandhu College, University of Delhi, Kalkaji, New Delhi, 110019, India
| | - Amit Kumar
- Department of Botany, Hansraj College, University of Delhi, Delhi, 110007, India
| | - Pooja Singh
- Public Health Research Institute, NJMS-Rutgers University, New Jersey, United States
| | - Moses Rinchui Ngasainao
- Department of Zoology, Deshbandhu College, University of Delhi, Kalkaji, New Delhi, 110019, India
| | - Archana Singh
- Department of Botany, Hansraj College, University of Delhi, Delhi, 110007, India.,Department of Molecular Ecology, Max-Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745 Jena, Germany
| | - Indrakant K Singh
- Molecular Biology Research Lab, Department of Zoology, Deshbandhu College, University of Delhi, Kalkaji, New Delhi, 110019, India.,Department of Molecular Ecology, Max-Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745 Jena, Germany
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Minias A, Brzostek A, Dziadek J. Targeting DNA Repair Systems in Antitubercular Drug Development. Curr Med Chem 2019; 26:1494-1505. [DOI: 10.2174/0929867325666180129093546] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/01/2017] [Accepted: 11/01/2017] [Indexed: 11/22/2022]
Abstract
Infections with Mycobacterium tuberculosis, the causative agent of tuberculosis, are difficult to treat using currently available chemotherapeutics. Clinicians agree on the urgent need for novel drugs to treat tuberculosis. In this mini review, we summarize data that prompts the consideration of DNA repair-associated proteins as targets for the development of new antitubercular compounds. We discuss data, including gene expression data, that highlight the importance of DNA repair genes during the pathogenic cycle as well as after exposure to antimicrobials currently in use. Specifically, we report experiments on determining the essentiality of DNA repair-related genes. We report the availability of protein crystal structures and summarize discovered protein inhibitors. Further, we describe phenotypes of available gene mutants of M. tuberculosis and model organisms Mycobacterium bovis and Mycobacterium smegmatis. We summarize experiments regarding the role of DNA repair-related proteins in pathogenesis and virulence performed both in vitro and in vivo during the infection of macrophages and animals. We detail the role of DNA repair genes in acquiring mutations, which influence the rate of drug resistance acquisition.
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Affiliation(s)
- Alina Minias
- Laboratory of Genetics and Physiology of Mycobacterium, Institute of Medical Biology, Polish Academy of Sciences, Lodz, Poland
| | - Anna Brzostek
- Laboratory of Genetics and Physiology of Mycobacterium, Institute of Medical Biology, Polish Academy of Sciences, Lodz, Poland
| | - Jarosław Dziadek
- Laboratory of Genetics and Physiology of Mycobacterium, Institute of Medical Biology, Polish Academy of Sciences, Lodz, Poland
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Abstract
Discontinuity of both strands of the chromosome is a lethal event in all living organisms because it compromises chromosome replication. As such, a diversity of DNA repair systems has evolved to repair double-strand DNA breaks (DSBs). In part, this diversity of DSB repair systems has evolved to repair breaks that arise in diverse physiologic circumstances or sequence contexts, including cellular states of nonreplication or breaks that arise between repeats. Mycobacteria elaborate a set of three genetically distinct DNA repair pathways: homologous recombination, nonhomologous end joining, and single-strand annealing. As such, mycobacterial DSB repair diverges substantially from the standard model of prokaryotic DSB repair and represents an attractive new model system. In addition, the presence in mycobacteria of a DSB repair system that can repair DSBs in nonreplicating cells (nonhomologous end joining) or when DSBs arise between repeats (single-strand annealing) has clear potential relevance to Mycobacterium tuberculosis pathogenesis, although the exact role of these systems in M. tuberculosis pathogenesis is still being elucidated. In this article we will review the genetics of mycobacterial DSB repair systems, focusing on recent insights.
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Badawi M, Giraud I, Vavre F, Grève P, Cordaux R. Signs of neutralization in a redundant gene involved in homologous recombination in Wolbachia endosymbionts. Genome Biol Evol 2014; 6:2654-64. [PMID: 25230723 PMCID: PMC4224334 DOI: 10.1093/gbe/evu207] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Genomic reduction in bacterial endosymbionts occurs through large genomic deletions and long-term accumulation of mutations. The latter process involves successive steps including gene neutralization, pseudogenization, and gradual erosion until complete loss. Although many examples of pseudogenes at various levels of degradation have been reported, neutralization cases are scarce because of the transient nature of the process. Gene neutralization may occur due to relaxation of selection in nonessential genes, for example, those involved in redundant functions. Here, we report an example of gene neutralization in the homologous recombination (HR) pathway of Wolbachia, a bacterial endosymbiont of arthropods and nematodes. The HR pathway is often depleted in endosymbiont genomes, but it is apparently intact in some Wolbachia strains. Analysis of 12 major HR genes showed that they have been globally under strong purifying selection during the evolution of Wolbachia strains hosted by arthropods, supporting the evolutionary importance of the HR pathway for these Wolbachia genomes. However, we detected signs of recent neutralization of the ruvA gene in a subset of Wolbachia strains, which might be related to an ancestral, clade-specific amino acid change that impaired DNA-binding activity. Strikingly, RuvA is part of the RuvAB complex involved in branch migration, whose function overlaps with the RecG helicase. Although ruvA is experiencing neutralization, recG is under strong purifying selection. Thus, our high phylogenetic resolution suggests that we identified a rare example of targeted neutralization of a gene involved in a redundant function in an endosymbiont genome.
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Affiliation(s)
- Myriam Badawi
- Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Poitiers, France
| | - Isabelle Giraud
- Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Poitiers, France
| | - Fabrice Vavre
- Université de Lyon, UMR CNRS 5558 Biométrie et Biologie Evolutive, Villeurbanne, France
| | - Pierre Grève
- Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Poitiers, France
| | - Richard Cordaux
- Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Poitiers, France
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Anusuya S, Natarajan J. The eradication of leprosy: molecular modeling techniques for novel drug discovery. Expert Opin Drug Discov 2013; 8:1239-51. [PMID: 23924296 DOI: 10.1517/17460441.2013.826188] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Leprosy is a slowly progressing bacterial infection caused by Mycobacterium leprae. The World Health Organization recommended multidrug therapy (MDT) which is extremely effective and halts the progress of the disease. Even though the objective of eliminating leprosy as a public health problem has been achieved successfully, leprosy is not yet eradicated. Furthermore, the long-term use of MDT results in single- and multidrug resistance. Therefore, there is still a need for new drug discovery for leprosy. AREAS COVERED The authors explain the importance of discovery of new drug to leprosy and the significance of homology modeling to drug discovery. This review highlights the principle steps, applications, and the resources of homology modeling. Finally, the authors emphasize the application of different structure-based drug design (SBDD) approaches to design novel therapeutics for leprosy. EXPERT OPINION MDT has proved to be effective in controlling infection, with prevalence of leprosy now predominantly isolated to the developing countries. The emergence of single- and multidrug-resistant strains of M. leprae has, however, provided some concern with the need for newer antibacterial agents. Drug resistance can be overcome by multi-targeted therapy. SBDD approaches, which reported many successful drugs, depend predominantly on the three-dimensional (3D) structure of drug targets. As of 2013, only very few experimental structures are available for M. leprae proteins. Hence, SBDD, in leprosy research, relies heavily on homology modeling to predict the 3D structure of drug targets and to design better therapeutics.
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Affiliation(s)
- Shanmugam Anusuya
- V.M.K.V. Engineering College, Department of Bioinformatics , Salem 636308, Tamil Nadu , India
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Selvaraj M, Ahmad R, Varshney U, Vijayan M. Structures of new crystal forms of Mycobacterium tuberculosis peptidyl-tRNA hydrolase and functionally important plasticity of the molecule. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:124-8. [PMID: 22297982 PMCID: PMC3274386 DOI: 10.1107/s1744309111052341] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 12/04/2011] [Indexed: 11/11/2022]
Abstract
The X-ray structures of new crystal forms of peptidyl-tRNA hydrolase from M. tuberculosis reported here and the results of previous X-ray studies of the enzyme from different sources provide a picture of the functionally relevant plasticity of the protein molecule. The new X-ray results confirm the connection deduced previously between the closure of the lid at the peptide-binding site and the opening of the gate that separates the peptide-binding and tRNA-binding sites. The plasticity of the molecule indicated by X-ray structures is in general agreement with that deduced from the available solution NMR results. The correlation between the lid and the gate movements is not, however, observed in the NMR structure.
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Affiliation(s)
- M. Selvaraj
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Rais Ahmad
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Umesh Varshney
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - M. Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
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Pathways for Holliday junction processing during homologous recombination in Saccharomyces cerevisiae. Mol Cell Biol 2011; 31:1921-33. [PMID: 21343337 DOI: 10.1128/mcb.01130-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Saccharomyces cerevisiae Rmi1 protein is a component of the highly conserved Sgs1-Top3-Rmi1 complex. Deletion of SGS1, TOP3, or RMI1 is synthetically lethal when combined with the loss of the Mus81-Mms4 or Slx1-Slx4 endonucleases, which have been implicated in Holliday junction (HJ) resolution. To investigate the causes of this synthetic lethality, we isolated a temperature-sensitive mutant of the RMI1 strain, referred to as the rmi1-1 mutant. At the restrictive temperature, this mutant phenocopies an rmi1Δ strain but behaves like the wild type at the permissive temperature. Following a transient exposure to methyl methanesulfonate, rmi1-1 mutants accumulate unprocessed homologous recombination repair (HRR) intermediates. These intermediates are slowly resolved at the restrictive temperature, revealing a redundant resolution activity when Rmi1 is impaired. This resolution depends on Mus81-Mms4 but not on either Slx1-Slx4 or another HJ resolvase, Yen1. Similar results were also observed when Top3 function was impaired. We propose that the Sgs1-Top3-Rmi1 complex constitutes the main pathway for the processing of HJ-containing HRR intermediates but that Mus81-Mms4 can also resolve these intermediates.
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Wang F, Yang Y, Singh TR, Busygina V, Guo R, Wan K, Wang W, Sung P, Meetei AR, Lei M. Crystal structures of RMI1 and RMI2, two OB-fold regulatory subunits of the BLM complex. Structure 2011; 18:1159-70. [PMID: 20826342 PMCID: PMC5955610 DOI: 10.1016/j.str.2010.06.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/03/2010] [Accepted: 06/07/2010] [Indexed: 11/17/2022]
Abstract
Mutations in BLM, a RecQ-like helicase, are linked to the autosomal recessive cancer-prone disorder Bloom's syndrome. BLM associates with topoisomerase (Topo) IIIα, RMI1, and RMI2 to form the BLM complex that is essential for genome stability. The RMI1-RMI2 heterodimer stimulates the dissolution of double Holliday junction into non-crossover recombinants mediated by BLM-Topo IIIα and is essential for stabilizing the BLM complex. However, the molecular basis of these functions of RMI1 and RMI2 remains unclear. Here we report the crystal structures of multiple domains of RMI1-RMI2, providing direct confirmation of the existence of three oligonucleotide/oligosaccharide binding (OB)-folds in RMI1-RMI2. Our structural and biochemical analyses revealed an unexpected insertion motif in RMI1N-OB, which is important for stimulating the dHJ dissolution. We also revealed the structural basis of the interaction between RMI1C-OB and RMI2-OB and demonstrated the functional importance of the RMI1-RMI2 interaction in genome stability maintenance.
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Affiliation(s)
- Feng Wang
- Howard Hughes Medical Institute, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Prabu JR, Thamotharan S, Khanduja JS, Chandra NR, Muniyappa K, Vijayan M. Crystallographic and modelling studies on Mycobacterium tuberculosis RuvA Additional role of RuvB-binding domain and inter species variability. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1001-9. [PMID: 19374958 DOI: 10.1016/j.bbapap.2009.04.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 04/06/2009] [Accepted: 04/06/2009] [Indexed: 11/28/2022]
Abstract
RuvA, along with RuvB, is involved in branch migration of heteroduplex DNA in homologous recombination. The structures of three new crystal forms of RuvA from Mycobacterium tuberculosis (MtRuvA) have been determined. The RuvB-binding domain is cleaved off in one of them. Detailed models of the complexes of octameric RuvA from different species with the Holliday junction have also been constructed. A thorough examination of the structures presented here and those reported earlier brings to light the hitherto unappreciated role of the RuvB-binding domain in determining inter-domain orientation and oligomerization. These structures also permit an exploration of the interspecies variability of structural features such as oligomerization and the conformation of the loop that carries the acidic pin, in terms of amino acid substitutions. These models emphasize the additional role of the RuvB-binding domain in Holliday junction binding. This role along with its role in oligomerization could have important biological implications.
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Affiliation(s)
- J Rajan Prabu
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
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