scholarly journals Non-Recombinogenic Functions of Rad51, BRCA2, and Rad52 in DNA Damage Tolerance

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1550
Author(s):  
Félix Prado
Keyword(s):  
Dna Damage ◽  
Homologous Recombination ◽  
Damage Tolerance ◽  
Molecular Switches ◽  
Strand Exchange ◽  
Template Switching ◽  
Replication Forks ◽  
Lesion Bypass ◽  
Dna Damage Tolerance ◽  
Exchange Activity

The DNA damage tolerance (DDT) response is aimed to timely and safely complete DNA replication by facilitating the advance of replication forks through blocking lesions. This process is associated with an accumulation of single-strand DNA (ssDNA), both at the fork and behind the fork. Lesion bypass and ssDNA filling can be performed by translation synthesis (TLS) and template switching mechanisms. TLS uses low-fidelity polymerases to incorporate a dNTP opposite the blocking lesion, whereas template switching uses a Rad51/ssDNA nucleofilament and the sister chromatid to bypass the lesion. Rad51 is loaded at this nucleofilament by two mediator proteins, BRCA2 and Rad52, and these three factors are critical for homologous recombination (HR). Here, we review recent advances showing that Rad51, BRCA2, and Rad52 perform some of these functions through mechanisms that do not require the strand exchange activity of Rad51: the formation and protection of reversed fork structures aimed to bypass blocking lesions, and the promotion of TLS. These findings point to the central HR proteins as potential molecular switches in the choice of the mechanism of DDT.

scholarly journals Opposite roles of Rad5 in DNA damage tolerance: playing in both error-free and mutagenic lesion bypass

2022 ◽  
Author(s):  
Katarzyna H Maslowska ◽  
Vincent Pagès
Keyword(s):  
Dna Damage ◽  
Damage Tolerance ◽  
Template Switching ◽  
Helicase Domain ◽  
Lesion Bypass ◽  
Dna Damage Tolerance ◽  
Domain Specific ◽  
Important Player ◽  
Human Ortholog ◽  
Single Lesion

DNA Damage Tolerance (DDT) funcPons to bypass replicaPon-blocking lesions and is divided into two disPnct pathways: error-prone Translesion Synthesis (TLS) and error-free Damage Avoidance (DA). Rad5 is an important player in these processes. Indeed, Saccharomyces cerevisiae Rad5 is a large mulPfuncPonal protein that contains three well defined domains: a RING domain that promotes PCNA polyubiquiPnaPon and a ssDNA-dependent ATPase/helicase domain, that are both conserved in Rad5 human ortholog HLTF. Yeast Rad5 also contains a Rev1-binding domain. In this study we used domain-specific mutants to address the contribuPon of each of the Rad5 funcPons to lesion tolerance. Using an assay based on the inserPon of a single lesion into a defined locus in the genome of a living yeast cell, we demonstrate that Rad5 plays opposite roles in lesion tolerance: i) Rad5 favors error-free lesion bypass by acPvaPng template switching through polyubiquiPnaPon of PCNA; ii) Rad5 is also required for TLS by recruiPng the TLS polymerase Rev1. We also show that the helicase acPvity does not play any role in lesion tolerance/

scholarly journals The Mgs1/WRNIP1 ATPase is required to prevent a recombination salvage pathway at damaged replication forks

2020 ◽  
Vol 6 (15) ◽  
pp. eaaz3327 ◽  
Author(s):  
Alberto Jiménez-Martín ◽  
Irene Saugar ◽  
Chinnu Rose Joseph ◽  
Alexandra Mayer ◽  
Carl P. Lehmann ◽  
...  
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Dna Lesions ◽  
Template Switching ◽  
Replication Forks ◽  
Salvage Pathway ◽  
Dna Damage Tolerance ◽  
Alternative Mode ◽  
Free Mode ◽  
Template Switch

DNA damage tolerance (DDT) is crucial for genome integrity maintenance. DDT is mainly carried out by template switch recombination, an error-free mode of overcoming DNA lesions, or translesion DNA synthesis, which is error-prone. Here, we investigated the role of Mgs1/WRNIP1 in modulating DDT. Using budding yeast, we found that elimination of Mgs1 in cells lacking Rad5, an essential protein for DDT, activates an alternative mode of DNA damage bypass, driven by recombination, which allows chromosome replication and cell viability under stress conditions that block DNA replication forks. This salvage pathway is RAD52 and RAD59 dependent, requires the DNA polymerase δ and PCNA modification at K164, and is enabled by Esc2 and the PCNA unloader Elg1, being inhibited when Mgs1 is present. We propose that Mgs1 is necessary to prevent a potentially toxic recombination salvage pathway at sites of perturbed replication, which, in turn, favors Rad5-dependent template switching, thus helping to preserve genome stability.

scholarly journals Monoubiquitylation of histone H2B contributes to the bypass of DNA damage during and after DNA replication

2017 ◽  
Vol 114 (11) ◽  
pp. E2205-E2214 ◽  
Author(s):  
Shih-Hsun Hung ◽  
Ronald P. Wong ◽  
Helle D. Ulrich ◽  
Cheng-Fu Kao
Keyword(s):  
Dna Damage ◽  
Replication Fork ◽  
Dna Lesions ◽  
Template Switching ◽  
Lesion Bypass ◽  
Dna Damage Tolerance ◽  
Cytological Evidence ◽  
Histone H2b ◽  
Chromatin Dynamics ◽  
Dna Lesion

DNA lesion bypass is mediated by DNA damage tolerance (DDT) pathways and homologous recombination (HR). The DDT pathways, which involve translesion synthesis and template switching (TS), are activated by the ubiquitylation (ub) of PCNA through components of the RAD6-RAD18 pathway, whereas the HR pathway is independent of RAD18. However, it is unclear how these processes are coordinated within the context of chromatin. Here we show that Bre1, an ubiquitin ligase specific for histone H2B, is recruited to chromatin in a manner coupled to replication of damaged DNA. In the absence of Bre1 or H2Bub, cells exhibit accumulation of unrepaired DNA lesions. Consequently, the damaged forks become unstable and resistant to repair. We provide physical, genetic, and cytological evidence that H2Bub contributes toward both Rad18-dependent TS and replication fork repair by HR. Using an inducible system of DNA damage bypass, we further show that H2Bub is required for the regulation of DDT after genome duplication. We propose that Bre1-H2Bub facilitates fork recovery and gap-filling repair by controlling chromatin dynamics in response to replicative DNA damage.

scholarly journals A conserved histone H3-H4 interface regulates DNA damage tolerance and homologous recombination during the recovery from replication stress

2021 ◽  
Author(s):  
Masafumi Hayashi ◽  
Kenji Keyamura ◽  
Asami Yoshida ◽  
Mariko Ariyoshi ◽  
Genki Akanuma ◽  
...  
Keyword(s):  
Dna Damage ◽  
Homologous Recombination ◽  
Damage Tolerance ◽  
Histone H3 ◽  
Wild Type ◽  
Dna Damage Tolerance ◽  
Damage Resistance ◽  
Replication Arrest ◽  
Induced Mutagenesis ◽  
Phase Progression

In eukaryotes, genomic DNA is packaged into nucleosomes, which are the basal components coordinating both the structures and functions of chromatin. Here we screened a collection of mutation for histone H3/H4 mutants in Saccharomyces cerevisiae that affect the DNA damage sensitivity of DNA damage tolerance (DDT)-deficient cells. We identified a class of histone H3/H4 mutations that suppress MMS sensitivity of DDT-deficient cells (hereafter we refer to as the histone SDD mutations), which likely cluster on a specific H3-H4 interface of the nucleosomes. The histone SDD mutations did not suppress the MMS sensitivity of DDT-deficient cells in the absence of Rad51, indicating that homologous recombination (HR) is responsible for DNA damage resistance. Furthermore, the histone SDD mutants showed reduced levels of PCNA ubiquitination after exposure to MMS or UV irradiation, consistent with a decreased MMS-induced mutagenesis relative to wild-type cells. We also found that histone SDD mutants lacking the INO80 chromatin remodeler impair HR-dependent recovery from MMS-induced replication arrest, resulting in defective S-phase progression and increased Rad52 foci. Taken together, our data provide novel insights into nucleosome functions, which link INO80-dependent chromatin remodeling to the regulation of DDT and HR during the recovery from replication blockage.

scholarly journals DNA damage tolerance in stem cells, ageing, mutagenesis, disease and cancer therapy

2019 ◽  
Vol 47 (14) ◽  
pp. 7163-7181 ◽  
Author(s):  
Bas Pilzecker ◽  
Olimpia Alessandra Buoninfante ◽  
Heinz Jacobs
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Damage Tolerance ◽  
Essential Feature ◽  
Dna Lesions ◽  
Template Switching ◽  
Dna Damage Tolerance ◽  
Response Network ◽  
Damage Response ◽  
Fork Stalling

AbstractThe DNA damage response network guards the stability of the genome from a plethora of exogenous and endogenous insults. An essential feature of the DNA damage response network is its capacity to tolerate DNA damage and structural impediments during DNA synthesis. This capacity, referred to as DNA damage tolerance (DDT), contributes to replication fork progression and stability in the presence of blocking structures or DNA lesions. Defective DDT can lead to a prolonged fork arrest and eventually cumulate in a fork collapse that involves the formation of DNA double strand breaks. Four principal modes of DDT have been distinguished: translesion synthesis, fork reversal, template switching and repriming. All DDT modes warrant continuation of replication through bypassing the fork stalling impediment or repriming downstream of the impediment in combination with filling of the single-stranded DNA gaps. In this way, DDT prevents secondary DNA damage and critically contributes to genome stability and cellular fitness. DDT plays a key role in mutagenesis, stem cell maintenance, ageing and the prevention of cancer. This review provides an overview of the role of DDT in these aspects.

scholarly journals Mechanisms of DNA Damage Tolerance: Post-Translational Regulation of PCNA

Genes ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 10 ◽  
Author(s):  
Wendy Leung ◽  
Ryan Baxley ◽  
George-Lucian Moldovan ◽  
Anja-Katrin Bielinsky
Keyword(s):  
Dna Damage ◽  
Translational Regulation ◽  
Damage Tolerance ◽  
Somatic Hypermutation ◽  
Critical Role ◽  
Nuclear Antigen ◽  
Template Switching ◽  
Dna Damage Tolerance ◽  
Class Switch ◽  
Dna Lesion

DNA damage is a constant source of stress challenging genomic integrity. To ensure faithful duplication of our genomes, mechanisms have evolved to deal with damage encountered during replication. One such mechanism is referred to as DNA damage tolerance (DDT). DDT allows for replication to continue in the presence of a DNA lesion by promoting damage bypass. Two major DDT pathways exist: error-prone translesion synthesis (TLS) and error-free template switching (TS). TLS recruits low-fidelity DNA polymerases to directly replicate across the damaged template, whereas TS uses the nascent sister chromatid as a template for bypass. Both pathways must be tightly controlled to prevent the accumulation of mutations that can occur from the dysregulation of DDT proteins. A key regulator of error-prone versus error-free DDT is the replication clamp, proliferating cell nuclear antigen (PCNA). Post-translational modifications (PTMs) of PCNA, mainly by ubiquitin and SUMO (small ubiquitin-like modifier), play a critical role in DDT. In this review, we will discuss the different types of PTMs of PCNA and how they regulate DDT in response to replication stress. We will also cover the roles of PCNA PTMs in lagging strand synthesis, meiotic recombination, as well as somatic hypermutation and class switch recombination.

scholarly journals PCNA Ubiquitylation: Instructive or Permissive to DNA Damage Tolerance Pathways?

Biomolecules ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1543
Author(s):  
Jun Che ◽  
Xin Hong ◽  
Hai Rao
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Damage Tolerance ◽  
Translesion Synthesis ◽  
Dna Lesions ◽  
Template Switching ◽  
Dna Damage Tolerance ◽  
Future Studies ◽  
Dna Lesion ◽  
Replicative Polymerases

DNA lesions escaping from repair often block the DNA replicative polymerases required for DNA replication and are handled during the S/G2 phases by the DNA damage tolerance (DDT) mechanisms, which include the error-prone translesion synthesis (TLS) and the error-free template switching (TS) pathways. Where the mono-ubiquitylation of PCNA K164 is critical for TLS, the poly-ubiquitylation of the same residue is obligatory for TS. However, it is not known how cells divide the labor between TLS and TS. Due to the fact that the type of DNA lesion significantly influences the TLS and TS choice, we propose that, instead of altering the ratio between the mono- and poly-Ub forms of PCNA, the competition between TLS and TS would automatically determine the selection between the two pathways. Future studies, especially the single integrated lesion “i-Damage” system, would elucidate detailed mechanisms governing the choices of specific DDT pathways.

scholarly journals PDIP38/PolDIP2 controls the DNA damage tolerance pathways by increasing the relative usage of translesion DNA synthesis over template switching

PLoS ONE ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. e0213383 ◽  
Author(s):  
Masataka Tsuda ◽  
Saki Ogawa ◽  
Masato Ooka ◽  
Kaori Kobayashi ◽  
Kouji Hirota ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Synthesis ◽  
Damage Tolerance ◽  
Template Switching ◽  
Dna Damage Tolerance ◽  
Translesion Dna Synthesis ◽  
Translesion Dna

DNA-damage tolerance through PCNA ubiquitination and sumoylation

2020 ◽  
Vol 477 (14) ◽  
pp. 2655-2677
Author(s):  
Li Fan ◽  
Tonghui Bi ◽  
Linxiao Wang ◽  
Wei Xiao
Keyword(s):  
Dna Damage ◽  
Posttranslational Modifications ◽  
Damage Tolerance ◽  
Nuclear Antigen ◽  
Replication Forks ◽  
Dna Damage Tolerance ◽  
Yeast Saccharomyces Cerevisiae ◽  
Dna Damaging Agents ◽  
Template Switch ◽  
Proliferating Cell

DNA-damage tolerance (DDT) is employed by eukaryotic cells to bypass replication-blocking lesions induced by DNA-damaging agents. In budding yeast Saccharomyces cerevisiae, DDT is mediated by RAD6 epistatic group genes and the central event for DDT is sequential ubiquitination of proliferating cell nuclear antigen (PCNA), a DNA clamp required for replication and DNA repair. DDT consists of two parallel pathways: error-prone DDT is mediated by PCNA monoubiquitination, which recruits translesion synthesis DNA polymerases to bypass lesions with decreased fidelity; and error-free DDT is mediated by K63-linked polyubiquitination of PCNA at the same residue of monoubiquitination, which facilitates homologous recombination-mediated template switch. Interestingly, the same PCNA residue is also subjected to sumoylation, which leads to inhibition of unwanted recombination at replication forks. All three types of PCNA posttranslational modifications require dedicated conjugating and ligation enzymes, and these enzymes are highly conserved in eukaryotes, from yeast to human.

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