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Juribašić Kulcsár M, Gabelica V, Plavec J. Solution-State Structure of a Long-Loop G-Quadruplex Formed Within Promoters of Plasmodium falciparum B var Genes. Chemistry 2024; 30:e202401190. [PMID: 38647110 DOI: 10.1002/chem.202401190] [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: 03/25/2024] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 04/25/2024]
Abstract
We report the high-resolution NMR solution-state structure of an intramolecular G-quadruplex with a diagonal loop of ten nucleotides. The G-quadruplex is formed by a 34-nt DNA sequence, d[CAG3T2A2G3TATA2CT3AG4T2AG3T2], named UpsB-Q-1. This sequence is found within promoters of the var genes of Plasmodium falciparum, which play a key role in malaria pathogenesis and evasion of the immune system. The [3+1]-hybrid G-quadruplex formed under physiologically relevant conditions exhibits a unique equilibrium between two structures, both stabilized by base stacking and non-canonical hydrogen bonding. Unique equilibrium of the two closely related 3D structures originates from a North-South repuckering of deoxyribose moiety of residue T27 in the lateral loop. Besides the 12 guanines involved in three G-quartets, most residues in loop regions are involved in interactions at both G-quartet-loop interfaces.
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Affiliation(s)
- Marina Juribašić Kulcsár
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, SI-1000, Ljubljana, Slovenia
- Division of Physical Chemistry, Ruđer Bošković Institute, Bijenička cesta 54, HR-10000, Zagreb, Croatia
| | - Valérie Gabelica
- School of Pharmaceutical Sciences, University of Geneva, 1 rue Michel-Servet, CH-1211, Geneva 4, Switzerland
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, SI-1000, Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000, Ljubljana, Slovenia
- EN-FIST Centre of Excellence, Trg OF 13, SI-1000, Ljubljana, Slovenia
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2
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Craven HM, Nettesheim G, Cicuta P, Blagborough AM, Merrick CJ. Effects of the G-quadruplex-binding drugs quarfloxin and CX-5461 on the malaria parasite Plasmodium falciparum. Int J Parasitol Drugs Drug Resist 2023; 23:106-119. [PMID: 38041930 PMCID: PMC10711401 DOI: 10.1016/j.ijpddr.2023.11.007] [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: 08/15/2023] [Revised: 11/15/2023] [Accepted: 11/20/2023] [Indexed: 12/04/2023]
Abstract
Plasmodium falciparum is the deadliest causative agent of human malaria. This parasite has historically developed resistance to most drugs, including the current frontline treatments, so new therapeutic targets are needed. Our previous work on guanine quadruplexes (G4s) in the parasite's DNA and RNA has highlighted their influence on parasite biology, and revealed G4 stabilising compounds as promising candidates for repositioning. In particular, quarfloxin, a former anticancer agent, kills blood-stage parasites at all developmental stages, with fast rates of kill and nanomolar potency. Here we explored the molecular mechanism of quarfloxin and its related derivative CX-5461. In vitro, both compounds bound to P. falciparum-encoded G4 sequences. In cellulo, quarfloxin was more potent than CX-5461, and could prevent establishment of blood-stage malaria in vivo in a murine model. CX-5461 showed clear DNA damaging activity, as reported in human cells, while quarfloxin caused weaker signatures of DNA damage. Both compounds caused transcriptional dysregulation in the parasite, but the affected genes were largely different, again suggesting different modes of action. Therefore, CX-5461 may act primarily as a DNA damaging agent in both Plasmodium parasites and mammalian cells, whereas the complete antimalarial mode of action of quarfloxin may be parasite-specific and remains somewhat elusive.
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Affiliation(s)
- Holly M Craven
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Guilherme Nettesheim
- Department of Physics, Cavendish Laboratory University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Pietro Cicuta
- Department of Physics, Cavendish Laboratory University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Andrew M Blagborough
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Catherine J Merrick
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK.
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3
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Ebel ER, Kim BY, McDew-White M, Egan ES, Anderson TJC, Petrov DA. Antigenic diversity in malaria parasites is maintained on extrachromosomal DNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.526885. [PMID: 36778235 PMCID: PMC9915586 DOI: 10.1101/2023.02.02.526885] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Sequence variation among antigenic var genes enables Plasmodium falciparum malaria parasites to evade host immunity. Using long sequence reads from haploid clones from a mutation accumulation experiment, we detect var diversity inconsistent with simple chromosomal inheritance. We discover putatively circular DNA that is strongly enriched for var genes, which exist in multiple alleles per locus separated by recombination and indel events. Extrachromosomal DNA likely contributes to rapid antigenic diversification in P. falciparum.
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Affiliation(s)
- Emily R Ebel
- Department of Biology, Stanford University, Stanford, CA, USA
- Department of Pediatrics, School of Medicine, Stanford University, Stanford, CA, USA
- Department of Microbiology and Immunology, School of Medicine, Stanford University, Stanford, CA, USA
| | - Bernard Y Kim
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Marina McDew-White
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
- Present address: Host Pathogen Interaction Program, Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Elizabeth S Egan
- Department of Pediatrics, School of Medicine, Stanford University, Stanford, CA, USA
- Department of Microbiology and Immunology, School of Medicine, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Timothy J C Anderson
- Disease Intervention and Prevention Program, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Dmitri A Petrov
- Department of Biology, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
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4
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Goyal M, Simantov K, Dzikowski R. Beyond splicing: serine-arginine proteins as emerging multifaceted regulators of RNA metabolism in malaria parasites. Curr Opin Microbiol 2022; 70:102201. [PMID: 36087463 DOI: 10.1016/j.mib.2022.102201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/01/2022] [Accepted: 08/09/2022] [Indexed: 01/25/2023]
Abstract
The serine-arginine-rich (SR) proteins play an exceptionally important role in eukaryotic gene expression, primarily by regulating constitutive and alternative splicing events. In addition to their primary role as splicing factors, SR proteins have emerged as multifunctional RNA-binding proteins that act as key regulators of almost every step of RNA metabolism. As in higher eukaryotes, Plasmodium parasites encode several SR proteins, which were implicated in pre-mRNA splicing. However, only a few have been characterized and their biological roles remain understudied. Intriguingly, in addition to splicing regulation, unexpected functions of particular SR proteins have been reported in Plasmodium in recent years. Here, we highlight the key characteristics and different noncanonical splicing functions of SR proteins and discuss potential mechanisms, which might be involved in their multifaceted functionality in Plasmodium.
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Affiliation(s)
- Manish Goyal
- Department of Microbiology & Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Karina Simantov
- Department of Microbiology & Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Ron Dzikowski
- Department of Microbiology & Molecular Genetics, The Kuvin Center for the Study of Infectious and Tropical Diseases, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
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5
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Severov V, Tsvetkov V, Barinov N, Babenko V, Klinov D, Pozmogova G. Spontaneous DNA Synapsis by Forming Noncanonical Intermolecular Structures. Polymers (Basel) 2022; 14:polym14102118. [PMID: 35632001 PMCID: PMC9144187 DOI: 10.3390/polym14102118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/14/2022] [Accepted: 05/20/2022] [Indexed: 01/27/2023] Open
Abstract
We report the spontaneous formation of DNA-DNA junctions in solution in the absence of proteins visualised using atomic force microscopy. The synapsis position fits with potential G-quadruplex (G4) sites. In contrast to the Holliday structure, these conjugates have an affinity for G4 antibodies. Molecular modelling was used to elucidate the possible G4/IM-synaptic complex structures. Our results indicate a new role of the intermolecular noncanonical structures in chromatin architecture and genomic rearrangement.
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Affiliation(s)
- Viacheslav Severov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
- Correspondence: (V.S.); (V.T.)
| | - Vladimir Tsvetkov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
- Institute of Biodesign and Complex System Modeling, I.M. Sechenov First Moscow State Medical University, Trubetskaya Str. 8-2, 119991 Moscow, Russia
- A.V. Topchiev Institute of Petrochemical Synthesis, Leninsky prospect Str. 29, 119991 Moscow, Russia
- Correspondence: (V.S.); (V.T.)
| | - Nikolay Barinov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
| | - Vladislav Babenko
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
| | - Dmitry Klinov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
- Peoples’ Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya str.6, 117198 Moscow, Russia
| | - Galina Pozmogova
- Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya Str. 1a, 119435 Moscow, Russia; (N.B.); (V.B.); (D.K.); (G.P.)
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6
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Dumetz F, Chow EYC, Harris LM, Liew SW, Jensen A, Umar MI, Chung B, Chan TF, Merrick CJ, Kwok CK. G-quadruplex RNA motifs influence gene expression in the malaria parasite Plasmodium falciparum. Nucleic Acids Res 2021; 49:12486-12501. [PMID: 34792144 PMCID: PMC8643661 DOI: 10.1093/nar/gkab1095] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/15/2021] [Accepted: 10/21/2021] [Indexed: 11/12/2022] Open
Abstract
G-quadruplexes are non-helical secondary structures that can fold in vivo in both DNA and RNA. In human cells, they can influence replication, transcription and telomere maintenance in DNA, or translation, transcript processing and stability of RNA. We have previously showed that G-quadruplexes are detectable in the DNA of the malaria parasite Plasmodium falciparum, despite a very highly A/T-biased genome with unusually few guanine-rich sequences. Here, we show that RNA G-quadruplexes can also form in P. falciparum RNA, using rG4-seq for transcriptome-wide structure-specific RNA probing. Many of the motifs, detected here via the rG4seeker pipeline, have non-canonical forms and would not be predicted by standard in silico algorithms. However, in vitro biophysical assays verified formation of non-canonical motifs. The G-quadruplexes in the P. falciparum transcriptome are frequently clustered in certain genes and associated with regions encoding low-complexity peptide repeats. They are overrepresented in particular classes of genes, notably those that encode PfEMP1 virulence factors, stress response genes and DNA binding proteins. In vitro translation experiments and in vivo measures of translation efficiency showed that G-quadruplexes can influence the translation of P. falciparum mRNAs. Thus, the G-quadruplex is a novel player in post-transcriptional regulation of gene expression in this major human pathogen.
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Affiliation(s)
- Franck Dumetz
- Department of Pathology, Cambridge University, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Eugene Yui-Ching Chow
- School of Life Sciences and State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, NT, Hong Kong
| | - Lynne M Harris
- Centre for Applied Entomology and Parasitology, Faculty of Natural Sciences, Keele University, Keele, Staffordshire, ST5 5BG, UK
| | - Shiau Wei Liew
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Anders Jensen
- Department of Pathology, Cambridge University, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Mubarak I Umar
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Betty Chung
- Department of Pathology, Cambridge University, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Ting Fung Chan
- School of Life Sciences and State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, NT, Hong Kong
| | - Catherine J Merrick
- Department of Pathology, Cambridge University, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Chun Kit Kwok
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.,Shenzhen Research Institute of City University of Hong Kong, Shenzhen, China
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7
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Xu J, Jiang R, He H, Ma C, Tang Z. Recent advances on G-quadruplex for biosensing, bioimaging and cancer therapy. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116257] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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8
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Gurung P, Gomes AR, Martins RM, Juranek SA, Alberti P, Mbang-Benet DE, Urbach S, Gazanion E, Guitard V, Paeschke K, Lopez-Rubio JJ. PfGBP2 is a novel G-quadruplex binding protein in Plasmodium falciparum. Cell Microbiol 2021; 23:e13303. [PMID: 33340385 DOI: 10.1111/cmi.13303] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 12/10/2020] [Accepted: 12/11/2020] [Indexed: 11/27/2022]
Abstract
Guanine-quadruplexes (G4s) are non-canonical DNA structures that can regulate key biological processes such as transcription, replication and telomere maintenance in several organisms including eukaryotes, prokaryotes and viruses. Recent reports have identified the presence of G4s within the AT-rich genome of Plasmodium falciparum, the protozoan parasite causing malaria. In Plasmodium, potential G4-forming sequences (G4FS) are enriched in the telomeric and sub-telomeric regions of the genome where they are associated with telomere maintenance and recombination events within virulence genes. However, there is a little understanding about the biological role of G4s and G4-binding proteins. Here, we provide the first snapshot of G4-interactome in P. falciparum using DNA pull-down assay followed by LC-MS/MS. Interestingly, we identified ~24 potential G4-binding proteins (G4-BP) that bind to a stable G4FS (AP2_G4). Furthermore, we characterised the role of G-strand binding protein 2 (PfGBP2), a putative telomere-binding protein in P. falciparum. We validated the interaction of PfGBP2 with G4 in vitro as well as in vivo. PfGBP2 is expressed throughout the intra-erythrocytic developmental cycle and is essential for the parasites in the presence of G4-stabilising ligand, pyridostatin. Gene knockout studies showed the role of PfGBP2 in the expression of var genes. Taken together, this study suggests that PfGBP2 is a bona fide G4-binding protein, which is likely to be involved in the regulation of G4-related functions in these malarial parasites. In addition, this study sheds light on this understudied G4 biology in P. falciparum.
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Affiliation(s)
- Pratima Gurung
- LPHI, UMR 5235, CNRS, INSERM, University of Montpellier, Montpellier, France.,Laboratory of Parasitology and Mycology, CNRS UMR 5290 MIVEGEC, University of Montpellier, Montpellier, France
| | - Ana Rita Gomes
- LPHI, UMR 5235, CNRS, INSERM, University of Montpellier, Montpellier, France.,Laboratory of Parasitology and Mycology, CNRS UMR 5290 MIVEGEC, University of Montpellier, Montpellier, France
| | - Rafael M Martins
- LPHI, UMR 5235, CNRS, INSERM, University of Montpellier, Montpellier, France
| | - Stefan A Juranek
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany
| | - Patrizia Alberti
- Laboratory Genome Structure and Instability, Muséum National d'Histoire Naturelle, CNRS UMR 7196, INSERM U 1154, Paris, France
| | - Diane-Ethna Mbang-Benet
- LPHI, UMR 5235, CNRS, INSERM, University of Montpellier, Montpellier, France.,Laboratory of Parasitology and Mycology, CNRS UMR 5290 MIVEGEC, University of Montpellier, Montpellier, France
| | - Serge Urbach
- BioCampus Montpellier, CNRS UMR 5203, IGF, Montpellier, France
| | - Elodie Gazanion
- Laboratory of Parasitology and Mycology, CNRS UMR 5290 MIVEGEC, University of Montpellier, Montpellier, France
| | - Vincent Guitard
- LPHI, UMR 5235, CNRS, INSERM, University of Montpellier, Montpellier, France.,Laboratory of Parasitology and Mycology, CNRS UMR 5290 MIVEGEC, University of Montpellier, Montpellier, France
| | - Katrin Paeschke
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany
| | - Jose-Juan Lopez-Rubio
- LPHI, UMR 5235, CNRS, INSERM, University of Montpellier, Montpellier, France.,Laboratory of Parasitology and Mycology, CNRS UMR 5290 MIVEGEC, University of Montpellier, Montpellier, France
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9
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Crucial Role of the C-Terminal Domain of Hfq Protein in Genomic Instability. Microorganisms 2020; 8:microorganisms8101598. [PMID: 33080799 PMCID: PMC7603069 DOI: 10.3390/microorganisms8101598] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/10/2020] [Accepted: 10/13/2020] [Indexed: 01/25/2023] Open
Abstract
G-rich DNA repeats that can form G-quadruplex structures are prevalent in bacterial genomes and are frequently associated with regulatory regions of genes involved in virulence, antigenic variation, and antibiotic resistance. These sequences are also inherently mutagenic and can lead to changes affecting cell survival and adaptation. Transcription of the G-quadruplex-forming repeat (G3T)n in E. coli, when mRNA comprised the G-rich strand, promotes G-quadruplex formation in DNA and increases rates of deletion of G-quadruplex-forming sequences. The genomic instability of G-quadruplex repeats may be a source of genetic variability that can influence alterations and evolution of bacteria. The DNA chaperone Hfq is involved in the genetic instability of these G-quadruplex sequences. Inactivation of the hfq gene decreases the genetic instability of G-quadruplex, demonstrating that the genomic instability of this regulatory element can be influenced by the E. coli highly pleiotropic Hfq protein, which is involved in small noncoding RNA regulation pathways, and DNA organization and packaging. We have shown previously that the protein binds to and stabilizes these sequences, increasing rates of their genomic instability. Here, we extend this analysis to characterize the role of the C-terminal domain of Hfq protein in interaction with G-quadruplex structures. This allows to better understand the function of this specific region of the Hfq protein in genomic instability.
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10
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Bryant JM, Baumgarten S, Dingli F, Loew D, Sinha A, Claës A, Preiser PR, Dedon PC, Scherf A. Exploring the virulence gene interactome with CRISPR/dCas9 in the human malaria parasite. Mol Syst Biol 2020; 16:e9569. [PMID: 32816370 PMCID: PMC7440042 DOI: 10.15252/msb.20209569] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/17/2020] [Accepted: 07/22/2020] [Indexed: 12/13/2022] Open
Abstract
Mutually exclusive expression of the var multigene family is key to immune evasion and pathogenesis in Plasmodium falciparum, but few factors have been shown to play a direct role. We adapted a CRISPR-based proteomics approach to identify novel factors associated with var genes in their natural chromatin context. Catalytically inactive Cas9 ("dCas9") was targeted to var gene regulatory elements, immunoprecipitated, and analyzed with mass spectrometry. Known and novel factors were enriched including structural proteins, DNA helicases, and chromatin remodelers. Functional characterization of PfISWI, an evolutionarily divergent putative chromatin remodeler enriched at the var gene promoter, revealed a role in transcriptional activation. Proteomics of PfISWI identified several proteins enriched at the var gene promoter such as acetyl-CoA synthetase, a putative MORC protein, and an ApiAP2 transcription factor. These findings validate the CRISPR/dCas9 proteomics method and define a new var gene-associated chromatin complex. This study establishes a tool for targeted chromatin purification of unaltered genomic loci and identifies novel chromatin-associated factors potentially involved in transcriptional control and/or chromatin organization of virulence genes in the human malaria parasite.
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Affiliation(s)
- Jessica M Bryant
- Biology of Host‐Parasite Interactions UnitInstitut PasteurParisFrance
- INSERM U1201ParisFrance
- CNRS ERL9195ParisFrance
| | - Sebastian Baumgarten
- Biology of Host‐Parasite Interactions UnitInstitut PasteurParisFrance
- INSERM U1201ParisFrance
- CNRS ERL9195ParisFrance
| | - Florent Dingli
- Institut CuriePSL Research UniversityCentre de RechercheMass Spectrometry and Proteomics FacilityParisFrance
| | - Damarys Loew
- Institut CuriePSL Research UniversityCentre de RechercheMass Spectrometry and Proteomics FacilityParisFrance
| | - Ameya Sinha
- School of Biological SciencesNanyang Technological UniversitySingaporeSingapore
- Antimicrobial Resistance Interdisciplinary Research GroupSingapore‐MIT Alliance for Research and TechnologySingaporeSingapore
| | - Aurélie Claës
- Biology of Host‐Parasite Interactions UnitInstitut PasteurParisFrance
- INSERM U1201ParisFrance
- CNRS ERL9195ParisFrance
| | - Peter R Preiser
- School of Biological SciencesNanyang Technological UniversitySingaporeSingapore
- Antimicrobial Resistance Interdisciplinary Research GroupSingapore‐MIT Alliance for Research and TechnologySingaporeSingapore
| | - Peter C Dedon
- Antimicrobial Resistance Interdisciplinary Research GroupSingapore‐MIT Alliance for Research and TechnologySingaporeSingapore
- Department of Biological EngineeringMassachusetts Institute of TechnologyCambridgeMAUSA
| | - Artur Scherf
- Biology of Host‐Parasite Interactions UnitInstitut PasteurParisFrance
- INSERM U1201ParisFrance
- CNRS ERL9195ParisFrance
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11
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Gazanion E, Lacroix L, Alberti P, Gurung P, Wein S, Cheng M, Mergny JL, Gomes AR, Lopez-Rubio JJ. Genome wide distribution of G-quadruplexes and their impact on gene expression in malaria parasites. PLoS Genet 2020; 16:e1008917. [PMID: 32628663 PMCID: PMC7365481 DOI: 10.1371/journal.pgen.1008917] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 07/16/2020] [Accepted: 06/08/2020] [Indexed: 12/15/2022] Open
Abstract
Mechanisms of transcriptional control in malaria parasites are still not fully understood. The positioning patterns of G-quadruplex (G4) DNA motifs in the parasite's AT-rich genome, especially within the var gene family which encodes virulence factors, and in the vicinity of recombination hotspots, points towards a possible regulatory role of G4 in gene expression and genome stability. Here, we carried out the most comprehensive genome-wide survey, to date, of G4s in the Plasmodium falciparum genome using G4Hunter, which identifies G4 forming sequences (G4FS) considering their G-richness and G-skewness. We show an enrichment of G4FS in nucleosome-depleted regions and in the first exon of var genes, a pattern that is conserved within the closely related Laverania Plasmodium parasites. Under G4-stabilizing conditions, i.e., following treatment with pyridostatin (a high affinity G4 ligand), we show that a bona fide G4 found in the non-coding strand of var promoters modulates reporter gene expression. Furthermore, transcriptional profiling of pyridostatin-treated parasites, shows large scale perturbations, with deregulation affecting for instance the ApiAP2 family of transcription factors and genes involved in ribosome biogenesis. Overall, our study highlights G4s as important DNA secondary structures with a role in Plasmodium gene expression regulation, sub-telomeric recombination and var gene biology.
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Affiliation(s)
- Elodie Gazanion
- MIVEGEC UMR IRD 224, CNRS 5290, Montpellier University, Montpellier, France
| | - Laurent Lacroix
- IBENS, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Patrizia Alberti
- "Structure and Instability of Genomes" laboratory, Muséum National d'Histoire Naturelle (MNHN), Inserm U1154, CNRS UMR 7196, Paris, France
| | - Pratima Gurung
- Laboratory of Pathogen-Host Interactions (LPHI), UMR5235, CNRS, Montpellier University, Montpellier, France
| | - Sharon Wein
- Laboratory of Pathogen-Host Interactions (LPHI), UMR5235, CNRS, Montpellier University, Montpellier, France
| | - Mingpan Cheng
- ARNA Laboratory, IECB, CNRS UMR5320, INSERM U1212, Bordeaux University, Pessac, France
| | - Jean-Louis Mergny
- ARNA Laboratory, IECB, CNRS UMR5320, INSERM U1212, Bordeaux University, Pessac, France
- Institute of Biophysics of the Czech Academy of Sciences, Czech Republic
- Laboratoire d’Optique et Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, France
| | - Ana Rita Gomes
- Laboratory of Pathogen-Host Interactions (LPHI), UMR5235, CNRS, Montpellier University, Montpellier, France
| | - Jose-Juan Lopez-Rubio
- MIVEGEC UMR IRD 224, CNRS 5290, Montpellier University, Montpellier, France
- Laboratory of Pathogen-Host Interactions (LPHI), UMR5235, CNRS, Montpellier University, Montpellier, France
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12
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Gage HL, Merrick CJ. Conserved associations between G-quadruplex-forming DNA motifs and virulence gene families in malaria parasites. BMC Genomics 2020; 21:236. [PMID: 32183702 PMCID: PMC7077173 DOI: 10.1186/s12864-020-6625-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 02/26/2020] [Indexed: 11/25/2022] Open
Abstract
Background The Plasmodium genus of malaria parasites encodes several families of antigen-encoding genes. These genes tend to be hyper-variable, highly recombinogenic and variantly expressed. The best-characterized family is the var genes, exclusively found in the Laveranian subgenus of malaria parasites infecting humans and great apes. Var genes encode major virulence factors involved in immune evasion and the maintenance of chronic infections. In the human parasite P. falciparum, var gene recombination and diversification appear to be promoted by G-quadruplex (G4) DNA motifs, which are strongly associated with var genes in P. falciparum. Here, we investigated how this association might have evolved across Plasmodium species – both Laverania and also more distantly related species which lack vars but encode other, more ancient variant gene families. Results The association between var genes and G4-forming motifs was conserved across Laverania, spanning ~ 1 million years of evolutionary time, with suggestive evidence for evolution of the association occurring within this subgenus. In rodent malaria species, G4-forming motifs were somewhat associated with pir genes, but this was not conserved in the Laverania, nor did we find a strong association of these motifs with any gene family in a second outgroup of avian malaria parasites. Secondly, we compared two different G4 prediction algorithms in their performance on extremely A/T-rich Plasmodium genomes, and also compared these predictions with experimental data from G4-seq, a DNA sequencing method for identifying G4-forming motifs. We found a surprising lack of concordance between the two algorithms and also between the algorithms and G4-seq data. Conclusions G4-forming motifs are uniquely strongly associated with Plasmodium var genes, suggesting a particular role for G4s in recombination and diversification of these genes. Secondly, in the A/T-rich genomes of Plasmodium species, the choice of prediction algorithm may be particularly influential when studying G4s in these important protozoan pathogens.
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Affiliation(s)
- Hunter L Gage
- Department of Pathology, Cambridge University, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Catherine J Merrick
- Department of Pathology, Cambridge University, Tennis Court Road, Cambridge, CB2 1QP, UK.
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13
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Exploration of copy number variation in genes related to anti-malarial drug resistance in Plasmodium falciparum. Gene 2020; 736:144414. [PMID: 32006594 DOI: 10.1016/j.gene.2020.144414] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/27/2020] [Accepted: 01/28/2020] [Indexed: 12/16/2022]
Abstract
Development of drug resistance in P. falciparum is one of the major problems associated with malaria treatment. Parasite genetic factors such as single nucleotide polymorphisms (SNPs) and copy number variations (CNV) have shown their role in drug resistance. Most of the studies have focused on the role of SNPs and drug resistance in parasite. However, it has also been shown that CNV is associated with adaptation and drug resistance in parasite. Hence, exploration of copy number polymorphism in essential genes of P. falciparum and their role in anti-malarial resistance is important. This review provides the recent information related to genetic profile of CNV marker in plasmepsin and other genes associated with drugresistanceinP. falciparum. It may be suggested that CNVs in plasmepsin genes are the major driver of piperaquine resistance. Moreover, CNVs in pfcrt and pfmdr1genes appear to play important role in adaptation and hence survival of the parasite. It may be hypothesized that targeting of CNV formation in the parasite could be beneficial for breakdown of its adaption in response to drug pressure.
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14
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Huckaby AC, Granum CS, Carey MA, Szlachta K, Al-Barghouthi B, Wang YH, Guler JL. Complex DNA structures trigger copy number variation across the Plasmodium falciparum genome. Nucleic Acids Res 2019; 47:1615-1627. [PMID: 30576466 PMCID: PMC6393310 DOI: 10.1093/nar/gky1268] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 12/04/2018] [Accepted: 12/07/2018] [Indexed: 02/06/2023] Open
Abstract
Antimalarial resistance is a major obstacle in the eradication of the human malaria parasite, Plasmodium falciparum. Genome amplifications, a type of DNA copy number variation (CNV), facilitate overexpression of drug targets and contribute to parasite survival. Long monomeric A/T tracks are found at the breakpoints of many Plasmodium resistance-conferring CNVs. We hypothesize that other proximal sequence features, such as DNA hairpins, act with A/T tracks to trigger CNV formation. By adapting a sequence analysis pipeline to investigate previously reported CNVs, we identified breakpoints in 35 parasite clones with near single base-pair resolution. Using parental genome sequence, we predicted the formation of stable hairpins within close proximity to all future breakpoint locations. Especially stable hairpins were predicted to form near five shared breakpoints, establishing that the initiating event could have occurred at these sites. Further in-depth analyses defined characteristics of these 'trigger sites' across the genome and detected signatures of error-prone repair pathways at the breakpoints. We propose that these two genomic signals form the initial lesion (hairpins) and facilitate microhomology-mediated repair (A/T tracks) that lead to CNV formation across this highly repetitive genome. Targeting these repair pathways in P. falciparum may be used to block adaptation to antimalarial drugs.
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Affiliation(s)
- Adam C Huckaby
- Department of Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Claire S Granum
- Department of Biology, University of Virginia, Charlottesville, VA 22908, USA
| | - Maureen A Carey
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia Health System, Charlottesville, VA 22908, USA.,Division of Infectious Diseases and International Health, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Karol Szlachta
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Basel Al-Barghouthi
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA.,Center for Public Health Genomics, University of Virginia, Charlottesville, VA 22908, USA
| | - Yuh-Hwa Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Jennifer L Guler
- Department of Biology, University of Virginia, Charlottesville, VA 22908, USA.,Division of Infectious Diseases and International Health, University of Virginia Health System, Charlottesville, VA 22908, USA
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15
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Xu R, Liu Y, Fan R, Liang R, Yue L, Liu S, Su XZ, Li J. Generation and functional characterisation of Plasmodium yoelii csp deletion mutants using a microhomology-based CRISPR/Cas9 method. Int J Parasitol 2019; 49:705-714. [PMID: 31202685 PMCID: PMC10993195 DOI: 10.1016/j.ijpara.2019.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/01/2019] [Accepted: 04/05/2019] [Indexed: 11/24/2022]
Abstract
CRISPR/Cas9 is a powerful genome editing method that has greatly facilitated functional studies in many eukaryotic organisms including malaria parasites. Due to the lack of genes encoding enzymes necessary for the non-homologous end joining DNA repair pathway, genetic manipulation of malaria parasite genomes is generally accomplished through homologous recombination requiring the presence of DNA templates. Recently, an alternative double-strand break repair pathway, microhomology-mediated end joining, was found in the Plasmodium falciparum parasite. Taking advantage of the MMEJ pathway, we developed a MMEJ-based CRISPR/Cas9 (mCRISPR) strategy to efficiently generate multiple mutant parasites simultaneously in genes with repetitive sequences. As a proof of principle, we successfully produced various size mutants in the central repeat region of the Plasmodium yoelii circumsporozoite surface protein without the use of template DNA. Monitoring mixed parasite populations and individual parasites with different sizes of CSP-CRR showed that the CSP-CRR plays a role in the development of mosquito stages, with severe developmental defects in parasites with large deletions in the repeat region. However, the majority of the csp mutant parasite clones grew similarly to the wild type P. yoelii 17XL parasite in mice. This study develops a useful technique to efficiently generate mutant parasites with deletions or insertions, and shows that the CSP-CRR plays a role in parasite development in mosquito.
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Affiliation(s)
- Ruixue Xu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Yanjing Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Ruoxi Fan
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Rui Liang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Lixia Yue
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Shengfa Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Xin-Zhuan Su
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jian Li
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
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16
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Plasmodium Genomics and Genetics: New Insights into Malaria Pathogenesis, Drug Resistance, Epidemiology, and Evolution. Clin Microbiol Rev 2019; 32:32/4/e00019-19. [PMID: 31366610 DOI: 10.1128/cmr.00019-19] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Protozoan Plasmodium parasites are the causative agents of malaria, a deadly disease that continues to afflict hundreds of millions of people every year. Infections with malaria parasites can be asymptomatic, with mild or severe symptoms, or fatal, depending on many factors such as parasite virulence and host immune status. Malaria can be treated with various drugs, with artemisinin-based combination therapies (ACTs) being the first-line choice. Recent advances in genetics and genomics of malaria parasites have contributed greatly to our understanding of parasite population dynamics, transmission, drug responses, and pathogenesis. However, knowledge gaps in parasite biology and host-parasite interactions still remain. Parasites resistant to multiple antimalarial drugs have emerged, while advanced clinical trials have shown partial efficacy for one available vaccine. Here we discuss genetic and genomic studies of Plasmodium biology, host-parasite interactions, population structures, mosquito infectivity, antigenic variation, and targets for treatment and immunization. Knowledge from these studies will advance our understanding of malaria pathogenesis, epidemiology, and evolution and will support work to discover and develop new medicines and vaccines.
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17
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Saranathan N, Biswas B, Patra A, Vivekanandan P. G-quadruplexes may determine the landscape of recombination in HSV-1. BMC Genomics 2019; 20:382. [PMID: 31096907 PMCID: PMC6524338 DOI: 10.1186/s12864-019-5731-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/24/2019] [Indexed: 12/13/2022] Open
Abstract
Background Several lines of evidence suggest that recombination plays a central role in replication and evolution of herpes simplex virus-1 (HSV-1). G-quadruplex (G4)-motifs have been linked to recombination events in human and microbial genomes, but their role in recombination has not been studied in DNA viruses. Results The availability of near full-length sequences from 40 HSV-1 recombinant strains with exact position of the recombination breakpoints provided us with a unique opportunity to investigate the role of G4-motifs in recombination among herpes viruses. We mapped the G4-motifs in the parental and all the 40 recombinant strains. Interestingly, the genome-wide distribution of breakpoints closely mirrors the G4 densities in the HSV-1 genome; regions of the genome with higher G4 densities had higher number of recombination breakpoints. Biophysical characterization of oligonucleotides from a subset of predicted G4-motifs confirmed the formation of G-quadruplex structures. Our analysis also reveals that G4-motifs are enriched in regions flanking the recombination breakpoints. Interestingly, about 11% of breakpoints lie within a G4-motif, making these DNA secondary structures hotspots for recombination in the HSV-1 genome. Breakpoints within G4-motifs predominantly lie within G4-clusters rather than individual G4-motifs. Of note, we identified the terminal guanosine of G4-clusters at the boundaries of the UL (unique long) region on either side of the OriL (origin of replication within UL) represented the commonest breakpoint among the HSV-1 recombinants. Conclusion Our findings suggest a correlation between the HSV-1 recombination landscape and the distribution of G4-motifs and G4-clusters, with possible implications for the evolution of DNA viruses. Electronic supplementary material The online version of this article (10.1186/s12864-019-5731-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nandhini Saranathan
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Banhi Biswas
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Anupam Patra
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Perumal Vivekanandan
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India.
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18
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Zhang X, Alexander N, Leonardi I, Mason C, Kirkman LA, Deitsch KW. Rapid antigen diversification through mitotic recombination in the human malaria parasite Plasmodium falciparum. PLoS Biol 2019; 17:e3000271. [PMID: 31083650 PMCID: PMC6532940 DOI: 10.1371/journal.pbio.3000271] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 05/23/2019] [Accepted: 04/30/2019] [Indexed: 11/18/2022] Open
Abstract
Malaria parasites possess the remarkable ability to maintain chronic infections that fail to elicit a protective immune response, characteristics that have stymied vaccine development and cause people living in endemic regions to remain at risk of malaria despite previous exposure to the disease. These traits stem from the tremendous antigenic diversity displayed by parasites circulating in the field. For Plasmodium falciparum, the most virulent of the human malaria parasites, this diversity is exemplified by the variant gene family called var, which encodes the major surface antigen displayed on infected red blood cells (RBCs). This gene family exhibits virtually limitless diversity when var gene repertoires from different parasite isolates are compared. Previous studies indicated that this remarkable genome plasticity results from extensive ectopic recombination between var genes during mitotic replication; however, the molecular mechanisms that direct this process to antigen-encoding loci while the rest of the genome remains relatively stable were not determined. Using targeted DNA double-strand breaks (DSBs) and long-read whole-genome sequencing, we show that a single break within an antigen-encoding region of the genome can result in a cascade of recombination events leading to the generation of multiple chimeric var genes, a process that can greatly accelerate the generation of diversity within this family. We also found that recombinations did not occur randomly, but rather high-probability, specific recombination products were observed repeatedly. These results provide a molecular basis for previously described structured rearrangements that drive diversification of this highly polymorphic gene family.
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Affiliation(s)
- Xu Zhang
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Noah Alexander
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States of America
| | - Irina Leonardi
- Jill Roberts Center for Inflammatory Bowel Disease, Weill Cornell Medical College, New York, New York, United States of America
| | - Christopher Mason
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States of America
- HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York, United States of America
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, New York, United States of America
- WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medical College, New York, New York, United States of America
| | - Laura A. Kirkman
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- Department of Internal Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, New York, United States of America
| | - Kirk W. Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
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19
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Parasitic Protozoa: Unusual Roles for G-Quadruplexes in Early-Diverging Eukaryotes. Molecules 2019; 24:molecules24071339. [PMID: 30959737 PMCID: PMC6480360 DOI: 10.3390/molecules24071339] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/02/2019] [Accepted: 04/03/2019] [Indexed: 12/17/2022] Open
Abstract
Guanine-quadruplex (G4) motifs, at both the DNA and RNA levels, have assumed an important place in our understanding of the biology of eukaryotes, bacteria and viruses. However, it is generally little known that their very first description, as well as the foundational work on G4s, was performed on protozoans: unicellular life forms that are often parasitic. In this review, we provide a historical perspective on the discovery of G4s, intertwined with their biological significance across the protozoan kingdom. This is a history in three parts: first, a period of discovery including the first characterisation of a G4 motif at the DNA level in ciliates (environmental protozoa); second, a period less dense in publications concerning protozoa, during which DNA G4s were discovered in both humans and viruses; and third, a period of renewed interest in protozoa, including more mechanistic work in ciliates but also in pathogenic protozoa. This last period has opened an exciting prospect of finding new anti-parasitic drugs to interfere with parasite biology, thus adding new compounds to the therapeutic arsenal.
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20
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Saranathan N, Vivekanandan P. G-Quadruplexes: More Than Just a Kink in Microbial Genomes. Trends Microbiol 2019; 27:148-163. [PMID: 30224157 PMCID: PMC7127049 DOI: 10.1016/j.tim.2018.08.011] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 08/17/2018] [Accepted: 08/24/2018] [Indexed: 02/06/2023]
Abstract
G-quadruplexes (G4s) are noncanonical nucleic acid secondary structures formed by guanine-rich DNA and RNA sequences. In this review we aim to provide an overview of the biological roles of G4s in microbial genomes with emphasis on recent discoveries. G4s are enriched and conserved in the regulatory regions of microbes, including bacteria, fungi, and viruses. Importantly, G4s in hepatitis B virus (HBV) and hepatitis C virus (HCV) genomes modulate genes crucial for virus replication. Recent studies on Epstein-Barr virus (EBV) shed light on the role of G4s within the microbial transcripts as cis-acting regulatory signals that modulate translation and facilitate immune evasion. Furthermore, G4s in microbial genomes have been linked to radioresistance, antigenic variation, recombination, and latency. G4s in microbial genomes represent novel therapeutic targets for antimicrobial therapy.
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Affiliation(s)
- Nandhini Saranathan
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Perumal Vivekanandan
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India.
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21
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Abstract
G-quadruplexes (G4s) have become one of the most exciting nucleic acid secondary structures. A noncanonical, four-stranded structure formed in guanine-rich DNA and RNA sequences, G-quadruplexes can readily form under physiologically relevant conditions and are globularly folded structures. DNA is widely recognized as a double-helical structure essential in genetic information storage. However, only ~3% of the human genome is expressed in protein; RNA and DNA may form noncanonical secondary structures that are functionally important. G-quadruplexes are one such example which have gained considerable attention for their formation and regulatory roles in biologically significant regions, such as human telomeres, oncogene-promoter regions, replication initiation sites, and 5'- and 3'-untranslated region (UTR) of mRNA. They are shown to be a regulatory motif in a number of critical cellular processes including gene transcription, translation, replication, and genomic stability. G-quadruplexes are also found in nonhuman genomes, particularly those of human pathogens. Therefore, G-quadruplexes have emerged as a new class of molecular targets for drug development. In addition, there is considerable interest in the use of G-quadruplexes for biomaterials, biosensors, and biocatalysts. The First International Meeting on Quadruplex DNA was held in 2007, and the G-quadruplex field has been growing dramatically over the last decade. The methods used to study G-quadruplexes have been essential to the rapid progress in our understanding of this exciting nucleic acid secondary structure.
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Affiliation(s)
- Danzhou Yang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, Purdue Center for Cancer Research, Purdue Institute for Drug Discovery, West Lafayette, IN USA
| | - Clement Lin
- Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN USA
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22
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Claessens A, Harris LM, Stanojcic S, Chappell L, Stanton A, Kuk N, Veneziano-Broccia P, Sterkers Y, Rayner JC, Merrick CJ. RecQ helicases in the malaria parasite Plasmodium falciparum affect genome stability, gene expression patterns and DNA replication dynamics. PLoS Genet 2018; 14:e1007490. [PMID: 29965959 PMCID: PMC6044543 DOI: 10.1371/journal.pgen.1007490] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 07/13/2018] [Accepted: 06/13/2018] [Indexed: 11/18/2022] Open
Abstract
The malaria parasite Plasmodium falciparum has evolved an unusual genome structure. The majority of the genome is relatively stable, with mutation rates similar to most eukaryotic species. However, some regions are very unstable with high recombination rates, driving the generation of new immune evasion-associated var genes. The molecular factors controlling the inconsistent stability of this genome are not known. Here we studied the roles of the two putative RecQ helicases in P. falciparum, PfBLM and PfWRN. When PfWRN was knocked down, recombination rates increased four-fold, generating chromosomal abnormalities, a high rate of chimeric var genes and many microindels, particularly in known ‘fragile sites’. This is the first identification of a gene involved in suppressing recombination and maintaining genome stability in Plasmodium. By contrast, no change in mutation rate appeared when the second RecQ helicase, PfBLM, was mutated. At the transcriptional level, however, both helicases evidently modulate the transcription of large cohorts of genes, with several hundred genes—including a large proportion of vars—showing deregulated expression in each RecQ mutant. Aberrant processing of stalled replication forks is a possible mechanism underlying elevated mutation rates and this was assessed by measuring DNA replication dynamics in the RecQ mutant lines. Replication forks moved slowly and stalled at elevated rates in both mutants, confirming that RecQ helicases are required for efficient DNA replication. Overall, this work identifies the Plasmodium RecQ helicases as major players in DNA replication, antigenic diversification and genome stability in the most lethal human malaria parasite, with important implications for genome evolution in this pathogen. Human malaria is caused by Plasmodium parasites, with most of the mortality (almost half a million deaths each year) being caused by one species, Plasmodium falciparum. This parasite has an unusual genome: it is exceptionally biased towards A and T nucleotides rather than G and C, and it contains specific areas rich in hypervariable virulence-associated genes which evolve very rapidly to produce new variants. This evolution is probably vital for the parasite to evade the human immune system and maintain chronic infections, but how it is controlled at a molecular level remains unknown. We have identified a helicase in the parasite with a huge influence on genome stability and the rate of genome evolution. It appears to function by unwinding various unusual DNA structures, and if this fails then the genome becomes unstable. In addition, the transcription of many genes whose DNA tends to form secondary structures is affected, and DNA replication is impeded. If this helicase was expressed variably in different parasite strains infecting humans, it could influence the parasites’ ability to grow and replicate efficiently, and also, crucially, its ability to evolve and thus evade the human immune system.
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Affiliation(s)
- Antoine Claessens
- London School of Hygiene and Tropical Medicine, London, United Kingdom
- Medical Research Council Unit The Gambia, Fajara, Banjul, The Gambia
| | - Lynne M. Harris
- Centre for Applied Entomology and Parasitology, Faculty of Natural Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Slavica Stanojcic
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, France
| | - Lia Chappell
- Malaria Programme, Wellcome Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Adam Stanton
- School of Computing and Mathematics, Faculty of Natural Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Nada Kuk
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, France
| | - Pamela Veneziano-Broccia
- Centre for Applied Entomology and Parasitology, Faculty of Natural Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Yvon Sterkers
- University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, France
- CNRS 5290 - IRD 224 - University of Montpellier (UMR “MiVEGEC”), Montpellier, France
- University Hospital Centre (CHU), Department of Parasitology-Mycology, Montpellier, France
| | - Julian C. Rayner
- Malaria Programme, Wellcome Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Catherine J. Merrick
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
- * E-mail:
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23
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G-Quadruplex DNA Motifs in the Malaria Parasite Plasmodium falciparum and Their Potential as Novel Antimalarial Drug Targets. Antimicrob Agents Chemother 2018; 62:AAC.01828-17. [PMID: 29311059 DOI: 10.1128/aac.01828-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/20/2017] [Indexed: 01/06/2023] Open
Abstract
G-quadruplexes are DNA or RNA secondary structures that can be formed from guanine-rich nucleic acids. These four-stranded structures, composed of stacked quartets of guanine bases, can be highly stable and have been demonstrated to occur in vivo in the DNA of human cells and other systems, where they play important biological roles, influencing processes such as telomere maintenance, DNA replication and transcription, or, in the case of RNA G-quadruplexes, RNA translation and processing. We report for the first time that DNA G-quadruplexes can be detected in the nuclei of the malaria parasite Plasmodium falciparum, which has one of the most A/T-biased genomes sequenced and therefore possesses few guanine-rich sequences with the potential to form G-quadruplexes. We show that despite this paucity of putative G-quadruplex-forming sequences, P. falciparum parasites are sensitive to several G-quadruplex-stabilizing drugs, including quarfloxin, which previously reached phase 2 clinical trials as an anticancer drug. Quarfloxin has a rapid initial rate of kill and is active against ring stages as well as replicative stages of intraerythrocytic development. We show that several G-quadruplex-stabilizing drugs, including quarfloxin, can suppress the transcription of a G-quadruplex-containing reporter gene in P. falciparum but that quarfloxin does not appear to disrupt the transcription of rRNAs, which was proposed as its mode of action in both human cells and trypanosomes. These data suggest that quarfloxin has potential for repositioning as an antimalarial with a novel mode of action. Furthermore, G-quadruplex biology in P. falciparum may present a target for development of other new antimalarial drugs.
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24
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Belmonte-Reche E, Martínez-García M, Guédin A, Zuffo M, Arévalo-Ruiz M, Doria F, Campos-Salinas J, Maynadier M, López-Rubio JJ, Freccero M, Mergny JL, Pérez-Victoria JM, Morales JC. G-Quadruplex Identification in the Genome of Protozoan Parasites Points to Naphthalene Diimide Ligands as New Antiparasitic Agents. J Med Chem 2018; 61:1231-1240. [PMID: 29323491 PMCID: PMC6148440 DOI: 10.1021/acs.jmedchem.7b01672] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
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G-quadruplexes
(G4) are DNA secondary structures that take part
in the regulation of gene expression. Putative G4 forming sequences
(PQS) have been reported in mammals, yeast, bacteria, and viruses.
Here, we present PQS searches on the genomes of T. brucei,
L. major, and P. falciparum. We found telomeric
sequences and new PQS motifs. Biophysical experiments showed that
EBR1, a 29 nucleotide long highly repeated PQS in T. brucei, forms a stable G4 structure. G4 ligands based on carbohydrate conjugated
naphthalene diimides (carb-NDIs) that bind G4’s including hTel
could bind EBR1 with selectivity versus dsDNA. These ligands showed
important antiparasitic activity. IC50 values were in the
nanomolar range against T. brucei with high selectivity
against MRC-5 human cells. Confocal microscopy confirmed these ligands
localize in the nucleus and kinetoplast of T. brucei suggesting they can reach their potential G4 targets. Cytotoxicity
and zebrafish toxicity studies revealed sugar conjugation reduces
intrinsic toxicity of NDIs.
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Affiliation(s)
- Efres Belmonte-Reche
- Department of Biochemistry and Molecular Pharmacology, Instituto de Parasitología y Biomedicina, CSIC , PTS Granada, Avda. del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Marta Martínez-García
- Department of Biochemistry and Molecular Pharmacology, Instituto de Parasitología y Biomedicina, CSIC , PTS Granada, Avda. del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Aurore Guédin
- ARNA Laboratory, Université de Bordeaux, Inserm U1212, CNRS UMR5320, Institut Européen de Chimie Biologie (IECB), 2 Rue Robert Escarpit, 33607 Pessac, France
| | - Michela Zuffo
- Department of Chemistry, University of Pavia , Via Taramelli 10, 27100 Pavia, Italy
| | - Matilde Arévalo-Ruiz
- Department of Biochemistry and Molecular Pharmacology, Instituto de Parasitología y Biomedicina, CSIC , PTS Granada, Avda. del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Filippo Doria
- Department of Chemistry, University of Pavia , Via Taramelli 10, 27100 Pavia, Italy
| | - Jenny Campos-Salinas
- Department of Biochemistry and Molecular Pharmacology, Instituto de Parasitología y Biomedicina, CSIC , PTS Granada, Avda. del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Marjorie Maynadier
- Dynamique des Interactions Membranaires Normales et Pathologiques, CNRS UMR 5235, Université de Montpellier, 34095 Montpellier, France
| | - José Juan López-Rubio
- CNRS, 5290, IRD 224, University of Montpellier (UMR "MiVEGEC"), INSERM, 34394 Montpellier, France
| | - Mauro Freccero
- Department of Chemistry, University of Pavia , Via Taramelli 10, 27100 Pavia, Italy
| | - Jean-Louis Mergny
- ARNA Laboratory, Université de Bordeaux, Inserm U1212, CNRS UMR5320, Institut Européen de Chimie Biologie (IECB), 2 Rue Robert Escarpit, 33607 Pessac, France.,Institute of Biophysics , AS CR, v.v.i. Kralovopolska 135, 612 65 Brno, Czech Republic
| | - José María Pérez-Victoria
- Department of Biochemistry and Molecular Pharmacology, Instituto de Parasitología y Biomedicina, CSIC , PTS Granada, Avda. del Conocimiento, 17, 18016 Armilla, Granada, Spain
| | - Juan Carlos Morales
- Department of Biochemistry and Molecular Pharmacology, Instituto de Parasitología y Biomedicina, CSIC , PTS Granada, Avda. del Conocimiento, 17, 18016 Armilla, Granada, Spain
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Anas M, Sharma R, Dhamodharan V, Pradeepkumar PI, Manhas A, Srivastava K, Ahmed S, Kumar N. Investigating Pharmacological Targeting of G-Quadruplexes in the Human Malaria Parasite. Biochemistry 2017; 56:6691-6699. [DOI: 10.1021/acs.biochem.7b00964] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Mohammad Anas
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
| | - Richa Sharma
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
| | - V. Dhamodharan
- Department
of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, Maharashtra, India
| | - P. I. Pradeepkumar
- Department
of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, Maharashtra, India
| | - Ashan Manhas
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
| | - Kumkum Srivastava
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Delhi, India
| | - Shakil Ahmed
- Molecular
and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Delhi, India
| | - Niti Kumar
- Parasitology
Division, CSIR-Central Drug Research Institute, Lucknow 226031, Uttar Pradesh, India
- Academy of Scientific and Innovative Research (AcSIR), Delhi, India
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26
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Kwok CK, Merrick CJ. G-Quadruplexes: Prediction, Characterization, and Biological Application. Trends Biotechnol 2017; 35:997-1013. [PMID: 28755976 DOI: 10.1016/j.tibtech.2017.06.012] [Citation(s) in RCA: 240] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 06/14/2017] [Accepted: 06/15/2017] [Indexed: 02/08/2023]
Abstract
Guanine (G)-rich sequences in nucleic acids can assemble into G-quadruplex structures that involve G-quartets linked by loop nucleotides. The structural and topological diversity of G-quadruplexes have attracted great attention for decades. Recent methodological advances have advanced the identification and characterization of G-quadruplexes in vivo as well as in vitro, and at a much higher resolution and throughput, which has greatly expanded our current understanding of G-quadruplex structure and function. Accumulating knowledge about the structural properties of G-quadruplexes has helped to design and develop a repertoire of molecular and chemical tools for biological applications. This review highlights how these exciting methods and findings have opened new doors to investigate the potential functions and applications of G-quadruplexes in basic and applied biosciences.
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Affiliation(s)
- Chun Kit Kwok
- Department of Chemistry, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China.
| | - Catherine J Merrick
- Centre for Applied Entomology and Parasitology, Faculty of Natural Sciences, Keele University, Keele, Staffordshire, UK.
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27
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Single-molecule analysis reveals that DNA replication dynamics vary across the course of schizogony in the malaria parasite Plasmodium falciparum. Sci Rep 2017. [PMID: 28638076 PMCID: PMC5479783 DOI: 10.1038/s41598-017-04407-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The mechanics of DNA replication and cell cycling are well-characterized in model organisms, but less is known about these basic aspects of cell biology in early-diverging Apicomplexan parasites, which do not divide by canonical binary fission but undergo unconventional cycles. Schizogony in the malaria parasite, Plasmodium, generates ~16–24 new nuclei via independent, asynchronous rounds of genome replication prior to cytokinesis and little is known about the control of DNA replication that facilitates this. We have characterised replication dynamics in P. falciparum throughout schizogony, using DNA fibre labelling and combing to visualise replication forks at a single-molecule level. We show that origins are very closely spaced in Plasmodium compared to most model systems, and that replication dynamics vary across the course of schizogony, from faster synthesis rates and more widely-spaced origins through to slower synthesis rates and closer-spaced origins. This is the opposite of the pattern usually seen across S-phase in human cells, when a single genome is replicated. Replication forks also appear to stall at an unusually high rate throughout schizogony. Our work explores Plasmodium DNA replication in unprecedented detail and opens up tremendous scope for analysing cell cycle dynamics and developing interventions targetting this unique aspect of malaria biology.
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28
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Tuteja R. Unraveling the importance of the malaria parasite helicases. FEBS J 2017; 284:2592-2603. [DOI: 10.1111/febs.14109] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 05/04/2017] [Accepted: 05/10/2017] [Indexed: 12/27/2022]
Affiliation(s)
- Renu Tuteja
- Parasite Biology Group; International Centre for Genetic Engineering and Biotechnology; New Delhi India
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29
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Kerkour A, Marquevielle J, Ivashchenko S, Yatsunyk LA, Mergny JL, Salgado GF. High-resolution three-dimensional NMR structure of the KRAS proto-oncogene promoter reveals key features of a G-quadruplex involved in transcriptional regulation. J Biol Chem 2017; 292:8082-8091. [PMID: 28330874 DOI: 10.1074/jbc.m117.781906] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 03/15/2017] [Indexed: 12/13/2022] Open
Abstract
Non-canonical base pairing within guanine-rich DNA and RNA sequences can produce G-quartets, whose stacking leads to the formation of a G-quadruplex (G4). G4s can coexist with canonical duplex DNA in the human genome and have been suggested to suppress gene transcription, and much attention has therefore focused on studying G4s in promotor regions of disease-related genes. For example, the human KRAS proto-oncogene contains a nuclease-hypersensitive element located upstream of the major transcription start site. The KRAS nuclease-hypersensitive element (NHE) region contains a G-rich element (22RT; 5'-AGGGCGGTGTGGGAATAGGGAA-3') and encompasses a Myc-associated zinc finger-binding site that regulates KRAS transcription. The NEH region therefore has been proposed as a target for new drugs that control KRAS transcription, which requires detailed knowledge of the NHE structure. In this study, we report a high-resolution NMR structure of the G-rich element within the KRAS NHE. We found that the G-rich element forms a parallel structure with three G-quartets connected by a four-nucleotide loop and two short one-nucleotide double-chain reversal loops. In addition, a thymine bulge is found between G8 and G9. The loops of different lengths and the presence of a bulge between the G-quartets are structural elements that potentially can be targeted by small chemical ligands that would further stabilize the structure and interfere or block transcriptional regulators such as Myc-associated zinc finger from accessing their binding sites on the KRAS promoter. In conclusion, our work suggests a possible new route for the development of anticancer agents that could suppress KRAS expression.
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Affiliation(s)
- Abdelaziz Kerkour
- From the Université Bordeaux, INSERM, CNRS, ARNA laboratory, European Institute of Chemistry and Biology, U1212, UMR 5320, 2 Rue Robert Escarpit, 33000 Pessac, France and
| | - Julien Marquevielle
- From the Université Bordeaux, INSERM, CNRS, ARNA laboratory, European Institute of Chemistry and Biology, U1212, UMR 5320, 2 Rue Robert Escarpit, 33000 Pessac, France and
| | - Stefaniia Ivashchenko
- From the Université Bordeaux, INSERM, CNRS, ARNA laboratory, European Institute of Chemistry and Biology, U1212, UMR 5320, 2 Rue Robert Escarpit, 33000 Pessac, France and
| | - Liliya A Yatsunyk
- From the Université Bordeaux, INSERM, CNRS, ARNA laboratory, European Institute of Chemistry and Biology, U1212, UMR 5320, 2 Rue Robert Escarpit, 33000 Pessac, France and.,Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, Pennsylvania 19081
| | - Jean-Louis Mergny
- From the Université Bordeaux, INSERM, CNRS, ARNA laboratory, European Institute of Chemistry and Biology, U1212, UMR 5320, 2 Rue Robert Escarpit, 33000 Pessac, France and
| | - Gilmar F Salgado
- From the Université Bordeaux, INSERM, CNRS, ARNA laboratory, European Institute of Chemistry and Biology, U1212, UMR 5320, 2 Rue Robert Escarpit, 33000 Pessac, France and
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30
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Malaria parasites possess a telomere repeat-binding protein that shares ancestry with transcription factor IIIA. Nat Microbiol 2017; 2:17033. [PMID: 28288093 DOI: 10.1038/nmicrobiol.2017.33] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 02/09/2017] [Indexed: 12/19/2022]
Abstract
Telomere repeat-binding factors (TRFs) are essential components of the molecular machinery that regulates telomere function. TRFs are widely conserved across eukaryotes and bind duplex telomere repeats via a characteristic MYB-type domain. Here, we identified the telomere repeat-binding protein PfTRZ in the malaria parasite Plasmodium falciparum, a member of the Alveolate phylum for which TRFs have not been described so far. PfTRZ lacks an MYB domain and binds telomere repeats via a C2H2-type zinc finger domain instead. In vivo, PfTRZ binds with high specificity to the telomeric tract and to interstitial telomere repeats upstream of subtelomeric virulence genes. Conditional depletion experiments revealed that PfTRZ regulates telomere length homeostasis and is required for efficient cell cycle progression. Intriguingly, we found that PfTRZ also binds to and regulates the expression of 5S rDNA genes. Combined with detailed phylogenetic analyses, our findings identified PfTRZ as a remote functional homologue of the basic transcription factor TFIIIA, which acquired a new function in telomere maintenance early in the apicomplexan lineage. Our work sheds unexpected new light on the evolution of telomere repeat-binding proteins and paves the way for dissecting the presumably divergent mechanisms regulating telomere functionality in one of the most deadly human pathogens.
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31
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Khrustalev VV, Khrustaleva TA, Sharma N, Giri R. Mutational Pressure in Zika Virus: Local ADAR-Editing Areas Associated with Pauses in Translation and Replication. Front Cell Infect Microbiol 2017; 7:44. [PMID: 28275585 PMCID: PMC5319961 DOI: 10.3389/fcimb.2017.00044] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 02/07/2017] [Indexed: 12/21/2022] Open
Abstract
Zika virus (ZIKV) spread led to the recent medical health emergency of international concern. Understanding the variations in virus system is of utmost need. Using available complete sequences of ZIKV we estimated directions of mutational pressure along the length of consensus sequences of three lineages of the virus. Results showed that guanine usage is growing in ZIKV RNA plus strand due to adenine to guanine transitions, while adenine usage is growing due to cytosine to adenine transversions. Especially high levels of guanine have been found in two-fold degenerated sites of certain areas of RNA plus strand with high amount of secondary structure. The usage of cytosine in two-fold degenerated sites shows direct dependence on the amount of secondary structure in 52% (consensus sequence of East African ZIKV lineage)—32% (consensus sequence of epidemic strains) of the length of RNA minus strand. These facts are the evidences of ADAR-editing of both strands of ZIKV genome during pauses in replication. RNA plus strand can also be edited by ADAR during pauses in translation caused by the appearance of groups of rare codons. According to our results, RNA minus strand of epidemic ZIKV strain has lower number of points in which polymerase can be stalled (allowing ADAR-editing) compared to other strains. The data on preferable directions of mutational pressure in epidemic ZIKV strain is useful for future vaccine development and understanding the evolution of new strains.
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Affiliation(s)
| | - Tatyana A Khrustaleva
- Laboratory of Cellular Technologies, Institute of Physiology of the National Academy of Sciences of Belarus Minsk, Belarus
| | - Nitin Sharma
- School of Basic Sciences, Indian Institute of Technology Mandi Mandi, India
| | - Rajanish Giri
- School of Basic Sciences, Indian Institute of Technology Mandi Mandi, India
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