scholarly journals Phosphoproteomics Reveals a Distinct Mode of Mec1/ATR Signaling in Response to DNA End Hyper-Resection

2020 ◽  
Author(s):  
Ethan J. Sanford ◽  
Vitor M. Faça ◽  
Stephanie C. Vega ◽  
William J. Comstock ◽  
Marcus B. Smolka
Keyword(s):  
Dna Repair ◽  
Scaffolding Protein ◽  
Genome Maintenance ◽  
Distinct Mode ◽  
Checkpoint Signaling ◽  
Ssdna Binding ◽  
Binding Domains ◽  
Ssdna Binding Protein ◽  
Atr Kinase ◽  
Dna Ends

ABSTRACTThe Mec1/ATR kinase is crucial for genome maintenance in response to a range of genotoxic insults, although how it promotes context-dependent signaling and DNA repair remains elusive. Here we uncovered a specialized mode of Mec1/ATR signaling triggered by the extensive nucleolytic processing (resection) of DNA ends. Cells lacking RAD9, a checkpoint activator and an inhibitor of resection, exhibit a selective increase in Mec1-dependent phosphorylation of proteins associated with single strand DNA transactions, including the ssDNA binding protein Rfa2, the translocase/ubiquitin ligase Uls1 and the HR-regulatory Sgs1-Top3-Rmi1 (STR) complex. Extensive Mec1-dependent phosphorylation of the STR complex, mostly on the Sgs1 helicase subunit, promotes an interaction between STR and the DNA repair scaffolding protein Dpb11. Fusion of Sgs1 to phosphopeptide-binding domains of Dpb11 strongly impairs HR-mediated repair, supporting a model whereby Mec1 signaling regulates STR upon hyper-resection to influence recombination outcomes. Overall, the identification of a distinct mode of Mec1 signaling triggered by hyper-resection highlights the multi-faceted action of this kinase in the coordination of checkpoint signaling and HR-mediated DNA repair.

scholarly journals Phosphoproteomics of ATR Signaling in Prophase I of Mouse Meiosis

2021 ◽  
Author(s):  
Jennie Sims ◽  
Vitor M Faca ◽  
Catalina Pereira ◽  
Gerardo A Arroyo-Martinez ◽  
Raimundo Freire ◽  
...  
Keyword(s):  
Dna Repair ◽  
Sex Chromosome ◽  
Phosphorylation Sites ◽  
Checkpoint Signaling ◽  
Genetic Ablation ◽  
Prophase I ◽  
Mrna Metabolism ◽  
Dna Damage Signaling ◽  
Meiotic Sex Chromosome Inactivation ◽  
Atr Kinase

During mammalian meiosis, the ATR kinase plays crucial roles in the coordination of DNA repair, meiotic sex chromosome inactivation and checkpoint signaling. Despite the importance of ATR in meiosis, the meiotic ATR signaling network remains largely unknown. Here we defined ATR signaling during prophase I in mice. Quantitative analysis of phosphoproteomes obtained after genetic ablation of the ATR-activating 9-1-1 complex or chemical inhibition of ATR revealed over 12,000 phosphorylation sites, of which 863 phosphorylation sites were dependent on both 9-1-1 and ATR. ATR and 9-1-1-dependent signaling was enriched for S/T-Q and S/T-X-X-K motifs and included proteins involved in DNA damage signaling, DNA repair, and piRNA and mRNA metabolism. We find that ATR targets the RNA processing factors SETX and RANBP3 and regulate their localization to the sex body. Overall, our analysis establishes a comprehensive map of ATR signaling in spermatocytes and highlights potential meiotic-specific actions of ATR during prophase I.

scholarly journals Replication protein A binds RNA and promotes R-loop formation

2020 ◽  
Author(s):  
Olga M. Mazina ◽  
Srinivas Somarowthu ◽  
Lyudmila Y. Kadyrova ◽  
Andrey G. Baranovskiy ◽  
Tahir H. Tahirov ◽  
...  
Keyword(s):  
Dna Replication ◽  
Protein A ◽  
Replication Protein A ◽  
Replication Protein ◽  
Loop Formation ◽  
Genome Maintenance ◽  
Ssdna Binding ◽  
Replication Restart ◽  
Ssdna Binding Protein

SUMMARYReplication protein A (RPA), a major eukaryotic ssDNA-binding protein, is essential for all metabolic processes that involve ssDNA including DNA replication, repair, and damage signaling. Surprisingly, we found here that RPA binds RNA in vitro with high affinity. Using native RIP method, we isolated RNA-RPA complexes from human cells. Furthermore, RPA promotes R-loop formation between RNA and homologous dsDNA. R-loops, the three-stranded nucleic acid structure consisting of an RNA-DNA hybrid and the displaced ssDNA strand, are common in human genome. R-loops may play an important role in transcription-coupled homologous recombination and DNA replication restart. We reconstituted the process of replication restart in vitro using RPA-generated R-loops and human DNA polymerases. These findings indicate that RPA may play a role in RNA metabolism and suggest a mechanism of genome maintenance that depends on RPA and RNA.

scholarly journals Compartmentalization of the replication fork by single-stranded DNA binding protein regulates translesion synthesis

2020 ◽  
Author(s):  
Seungwoo Chang ◽  
Elizabeth S. Thrall ◽  
Luisa Laureti ◽  
Vincent Pagès ◽  
Joseph J. Loparo
Keyword(s):  
Dna Replication ◽  
Binding Protein ◽  
Translesion Synthesis ◽  
Genome Maintenance ◽  
Ssdna Binding ◽  
Epsilon Subunit ◽  
Pol Iv ◽  
Ssdna Binding Protein ◽  
Pol Iii

AbstractDNA replication is mediated by the coordinated actions of multiple enzymes within replisomes. Processivity clamps tether many of these enzymes to DNA, allowing access to the primer/template junction. Many clamp-interacting proteins (CLIPs) are involved in genome maintenance pathways including translesion synthesis (TLS). Despite their abundance, DNA replication in bacteria is not perturbed by these CLIPs. Here we show that while the TLS polymerase Pol IV is largely excluded from moving replisomes, the remodeling of ssDNA binding protein (SSB) upon replisome stalling enriches Pol IV at replication forks. This enrichment is indispensable for Pol IV-mediated TLS on both the leading and lagging strands as it enables Pol IV-processivity clamp binding by overcoming the gatekeeping role of the Pol III epsilon subunit. As we have demonstrated for the Pol IV-SSB interaction, we propose that the binding of CLIPs to the processivity clamp must be preceded by interactions with factors that serve as localization markers for their site of action.

scholarly journals A key interaction with RPA orients XPA in NER complexes

2020 ◽  
Vol 48 (4) ◽  
pp. 2173-2188 ◽  
Author(s):  
Agnieszka M Topolska-Woś ◽  
Norie Sugitani ◽  
John J Cordoba ◽  
Kateryna V Le Meur ◽  
Rémy A Le Meur ◽  
...  
Keyword(s):  
Structural Model ◽  
Excision Repair ◽  
Mechanical Action ◽  
Scattering Data ◽  
Missense Mutations ◽  
Ssdna Binding ◽  
Binding Domains ◽  
X Ray Scattering ◽  
Protein Functions ◽  
Ssdna Binding Protein

Abstract The XPA protein functions together with the single-stranded DNA (ssDNA) binding protein RPA as the central scaffold to ensure proper positioning of repair factors in multi-protein nucleotide excision repair (NER) machinery. We previously determined the structure of a short motif in the disordered XPA N-terminus bound to the RPA32C domain. However, a second contact between the XPA DNA-binding domain (XPA DBD) and the RPA70AB tandem ssDNA-binding domains, which is likely to influence the orientation of XPA and RPA on the damaged DNA substrate, remains poorly characterized. NMR was used to map the binding interfaces of XPA DBD and RPA70AB. Combining NMR and X-ray scattering data with comprehensive docking and refinement revealed how XPA DBD and RPA70AB orient on model NER DNA substrates. The structural model enabled design of XPA mutations that inhibit the interaction with RPA70AB. These mutations decreased activity in cell-based NER assays, demonstrating the functional importance of XPA DBD–RPA70AB interaction. Our results inform ongoing controversy about where XPA is bound within the NER bubble, provide structural insights into the molecular basis for malfunction of disease-associated XPA missense mutations, and contribute to understanding of the structure and mechanical action of the NER machinery.

scholarly journals Insight into dynamics of APOBEC3G protein in complexes with DNA assessed by high speed AFM

2019 ◽  
Author(s):  
Yangang Pan ◽  
Luda S. Shlyakhtenko ◽  
Yuri L. Lyubchenko
Keyword(s):  
High Speed ◽  
Molecular Mechanisms ◽  
Catalytic Domain ◽  
Structural Information ◽  
Dynamic Structure ◽  
Time Lapse ◽  
Ssdna Binding ◽  
Binding Domains ◽  
Ssdna Binding Protein ◽  
Dumbbell Structure

AbstractAPOBEC3G (A3G) is a single-stranded DNA (ssDNA) binding protein that restricts the HIV virus by deamination of dC to dU during reverse transcription of the viral genome. A3G has two zing-binding domains: the N-terminal domain (NTD), which efficiently binds ssDNA, and the C-terminal catalytic domain (CTD), which supports deaminase activity of A3G. Until now, structural information on A3G has lacked, preventing elucidation of the molecular mechanisms underlying its interaction with ssDNA and deaminase activity. We have recently built computational model for the full-length A3G monomer and validated its structure by data obtained from time-lapse High-Speed Atomic Force Microscopy (HS AFM). Here time-lapse HS AFM was applied to directly visualize the structure and dynamics of A3G in complexes with ssDNA. Our results demonstrate a highly dynamic structure of A3G, where two domains of the protein fluctuate between compact globular and extended dumbbell structures. Quantitative analysis of our data revealed a substantial increase in the number of A3G dumbbell structures in the presence of the DNA substrate, suggesting the interaction of A3G with the ssDNA substrate stabilizes this dumbbell structure. Based on these data, we developed a model explaining the interaction of globular and dumbbell structures of A3G with ssDNA and suggested a possible role of the dumbbell structure in A3G function.

scholarly journals The Bloom syndrome complex senses RPA-coated single-stranded DNA to restart stalled replication forks

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ann-Marie K. Shorrocks ◽  
Samuel E. Jones ◽  
Kaima Tsukada ◽  
Carl A. Morrow ◽  
Zoulikha Belblidia ◽  
...  
Keyword(s):  
Replication Stress ◽  
Bloom Syndrome ◽  
Holliday Junctions ◽  
Replication Forks ◽  
Single Stranded Dna ◽  
Ssdna Binding ◽  
Ssdna Binding Protein ◽  
Dna Replication Stress ◽  
Dna End Resection ◽  
Stalled Replication Forks

AbstractThe Bloom syndrome helicase BLM interacts with topoisomerase IIIα (TOP3A), RMI1 and RMI2 to form the BTR complex, which dissolves double Holliday junctions to produce non-crossover homologous recombination (HR) products. BLM also promotes DNA-end resection, restart of stalled replication forks, and processing of ultra-fine DNA bridges in mitosis. How these activities of the BTR complex are regulated in cells is still unclear. Here, we identify multiple conserved motifs within the BTR complex that interact cooperatively with the single-stranded DNA (ssDNA)-binding protein RPA. Furthermore, we demonstrate that RPA-binding is required for stable BLM recruitment to sites of DNA replication stress and for fork restart, but not for its roles in HR or mitosis. Our findings suggest a model in which the BTR complex contains the intrinsic ability to sense levels of RPA-ssDNA at replication forks, which controls BLM recruitment and activation in response to replication stress.

scholarly journals Stabilization of a G-Quadruplex from Unfolding by Replication Protein A Using Potassium and the Porphyrin TMPyP4

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
Aishwarya Prakash ◽  
Fabien Kieken ◽  
Luis A. Marky ◽  
Gloria E. O. Borgstahl
Keyword(s):  
Dna Replication ◽  
Protein A ◽  
Thermal Stabilization ◽  
Replication Protein A ◽  
Replication Protein ◽  
Unique Problem ◽  
Ssdna Binding ◽  
Binding Domains ◽  
G Quadruplex ◽  
Stabilization Effect

Replication protein A (RPA) plays an essential role in DNA replication by binding and unfolding non-canonical single-stranded DNA (ssDNA) structures. Of the six RPA ssDNA binding domains (labeled A-F), RPA-CDE selectively binds a G-quadruplex forming sequence (5′-TAGGGGAAGGGTTGGAGTGGGTT-3′called Gq23). In K+, Gq23 forms a mixed parallel/antiparallel conformation, and in Na+Gq23 has a less stable (TMlowered by ∼20∘C), antiparallel conformation. Gq23 is intramolecular and 1D NMR confirms a stable G-quadruplex structure in K+. Full-length RPA and RPA-CDE-core can bind and unfold the Na+form of Gq23 very efficiently, but complete unfolding is not observed with the K+form. Studies with G-quadruplex ligands, indicate that TMPyP4 has a thermal stabilization effect on Gq23 in K+, and inhibits complete unfolding by RPA and RPA-CDE-core. Overall these data indicate that G-quadruplexes present a unique problem for RPA to unfold and ligands, such as TMPyP4, could possibly hinder DNA replication by blocking unfolding by RPA.

scholarly journals Imaging and energetics of single SSB-ssDNA molecules reveal intramolecular condensation and insight into RecOR function

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Jason C Bell ◽  
Bian Liu ◽  
Stephen C Kowalczykowski
Keyword(s):  
Long Range ◽  
Single Molecule ◽  
Magnetic Tweezers ◽  
Intramolecular Interactions ◽  
Ssdna Binding ◽  
Ssdna Binding Protein ◽  
Intramolecular Condensation ◽  
Nucleoprotein Complexes ◽  
Ssdna Binding Proteins ◽  
Dna Maintenance

Escherichia coli single-stranded DNA (ssDNA) binding protein (SSB) is the defining bacterial member of ssDNA binding proteins essential for DNA maintenance. SSB binds ssDNA with a variable footprint of ∼30–70 nucleotides, reflecting partial or full wrapping of ssDNA around a tetramer of SSB. We directly imaged single molecules of SSB-coated ssDNA using total internal reflection fluorescence (TIRF) microscopy and observed intramolecular condensation of nucleoprotein complexes exceeding expectations based on simple wrapping transitions. We further examined this unexpected property by single-molecule force spectroscopy using magnetic tweezers. In conditions favoring complete wrapping, SSB engages in long-range reversible intramolecular interactions resulting in condensation of the SSB-ssDNA complex. RecO and RecOR, which interact with SSB, further condensed the complex. Our data support the idea that RecOR--and possibly other SSB-interacting proteins—function(s) in part to alter long-range, macroscopic interactions between or throughout nucleoprotein complexes by microscopically altering wrapping and bridging distant sites.

scholarly journals Mechanisms of Nucleosome Reorganization by PARP1

2021 ◽  
Vol 22 (22) ◽  
pp. 12127
Author(s):  
Natalya V. Maluchenko ◽  
Dmitry K. Nilov ◽  
Sergey V. Pushkarev ◽  
Elena Y. Kotova ◽  
Nadezhda S. Gerasimova ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Dna Repair ◽  
Gene Regulation ◽  
Transcription Initiation ◽  
Histone H1 ◽  
Linker Histone ◽  
Gene Promoters ◽  
Linker Histone H1 ◽  
Nucleosomal Dna ◽  
Dna Ends

Poly(ADP-ribose) polymerase 1 (PARP1) is an enzyme involved in DNA repair, chromatin organization and transcription. During transcription initiation, PARP1 interacts with gene promoters where it binds to nucleosomes, replaces linker histone H1 and participates in gene regulation. However, the mechanisms of PARP1-nucleosome interaction remain unknown. Here, using spFRET microscopy, molecular dynamics and biochemical approaches we identified several different PARP1-nucleosome complexes and two types of PARP1 binding to mononucleosomes: at DNA ends and end-independent. Two or three molecules of PARP1 can bind to a nucleosome depending on the presence of linker DNA and can induce reorganization of the entire nucleosome that is independent of catalytic activity of PARP1. Nucleosome reorganization depends upon binding of PARP1 to nucleosomal DNA, likely near the binding site of linker histone H1. The data suggest that PARP1 can induce the formation of an alternative nucleosome state that is likely involved in gene regulation and DNA repair.

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