scholarly journals The Role of PCNA Posttranslational Modifications in Translesion Synthesis

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Montaser Shaheen ◽  
Ilanchezhian Shanmugam ◽  
Robert Hromas
Keyword(s):  
Posttranslational Modifications ◽  
Translesion Synthesis ◽  
Dna Lesions ◽  
Nuclear Antigen ◽  
Proliferative Cell Nuclear Antigen ◽  
Lesion Bypass ◽  
Sumo Ligase ◽  
Fork Stalling ◽  
The Individual ◽  
Template Switch

Organisms are predisposed to different types in DNA damage. Multiple mechanisms have evolved to deal with the individual DNA lesions. Translesion synthesis is a special pathway that enables the replication fork to bypass blocking lesions. Proliferative Cell Nuclear Antigen (PCNA), which is an essential component of the fork, undergoes posttranslational modifications, particularly ubiquitylation and sumoylation that are critical for lesion bypass and for filling of DNA gaps which result from this bypass. A special ubiquitylation system, represented by the Rad6 group of ubiquitin conjugating and ligating enzymes, mediates PCNA mono- and polyubiquitylation in response to fork stalling. The E2 SUMO conjugating enzyme Ubc9 and the E3 SUMO ligase Siz1 are responsible for PCNA sumoylation during undisturbed S phase and in response to fork stalling as well. PCNA monoubiquitylation mediated by Rad6/Rad18 recruits special polymerases to bypass the lesion and fill in the DNA gaps. PCNA polyubiquitylation achieved by ubc13-mms2/Rad 5 in yeast mediates an error-free pathway of lesion bypass likely through template switch. PCNA sumoylation appears required for this error-free pathway, and it plays an antirecombinational role during normal replication by recruiting the helicase Srs2 to prevent sister chromatid exchange and hyper-recombination.

scholarly journals DNA damage-specific deubiquitination regulates Rad18 functions to suppress mutagenesis

2014 ◽  
Vol 206 (2) ◽  
pp. 183-197 ◽  
Author(s):  
Michelle K. Zeman ◽  
Jia-Ren Lin ◽  
Raimundo Freire ◽  
Karlene A. Cimprich
Keyword(s):  
Dna Damage ◽  
Dna Lesions ◽  
Nuclear Antigen ◽  
Lesion Bypass ◽  
Dna Damage Tolerance ◽  
E3 Ligases ◽  
Plant Homeodomain ◽  
In Trans ◽  
Fork Stalling ◽  
Proliferating Cell

Deoxyribonucleic acid (DNA) lesions encountered during replication are often bypassed using DNA damage tolerance (DDT) pathways to avoid prolonged fork stalling and allow for completion of DNA replication. Rad18 is a central E3 ubiquitin ligase in DDT, which exists in a monoubiquitinated (Rad18•Ub) and nonubiquitinated form in human cells. We find that Rad18 is deubiquitinated when cells are treated with methyl methanesulfonate or hydrogen peroxide. The ubiquitinated form of Rad18 does not interact with SNF2 histone linker plant homeodomain RING helicase (SHPRH) or helicase-like transcription factor, two downstream E3 ligases needed to carry out error-free bypass of DNA lesions. Instead, it interacts preferentially with the zinc finger domain of another, nonubiquitinated Rad18 and may inhibit Rad18 function in trans. Ubiquitination also prevents Rad18 from localizing to sites of DNA damage, inducing proliferating cell nuclear antigen monoubiquitination, and suppressing mutagenesis. These data reveal a new role for monoubiquitination in controlling Rad18 function and suggest that damage-specific deubiquitination promotes a switch from Rad18•Ub–Rad18 complexes to the Rad18–SHPRH complexes necessary for error-free lesion bypass in cells.

scholarly journals Multisite SUMOylation restrains DNA polymerase η interactions with DNA damage sites

2020 ◽  
Vol 295 (25) ◽  
pp. 8350-8362 ◽  
Author(s):  
Claire Guérillon ◽  
Stine Smedegaard ◽  
Ivo A. Hendriks ◽  
Michael L. Nielsen ◽  
Niels Mailand
Keyword(s):  
Dna Damage ◽  
Dna Polymerase ◽  
Feedback Inhibition ◽  
Dna Lesions ◽  
Nuclear Antigen ◽  
Inhibition Mechanism ◽  
Proteomic Profiling ◽  
Lesion Bypass ◽  
Y Family ◽  
Damaged Dna

Translesion DNA synthesis (TLS) mediated by low-fidelity DNA polymerases is an essential cellular mechanism for bypassing DNA lesions that obstruct DNA replication progression. However, the access of TLS polymerases to the replication machinery must be kept tightly in check to avoid excessive mutagenesis. Recruitment of DNA polymerase η (Pol η) and other Y-family TLS polymerases to damaged DNA relies on proliferating cell nuclear antigen (PCNA) monoubiquitylation and is regulated at several levels. Using a microscopy-based RNAi screen, here we identified an important role of the SUMO modification pathway in limiting Pol η interactions with DNA damage sites in human cells. We found that Pol η undergoes DNA damage- and protein inhibitor of activated STAT 1 (PIAS1)-dependent polySUMOylation upon its association with monoubiquitylated PCNA, rendering it susceptible to extraction from DNA damage sites by SUMO-targeted ubiquitin ligase (STUbL) activity. Using proteomic profiling, we demonstrate that Pol η is targeted for multisite SUMOylation, and that collectively these SUMO modifications are essential for PIAS1- and STUbL-mediated displacement of Pol η from DNA damage sites. These findings suggest that a SUMO-driven feedback inhibition mechanism is an intrinsic feature of TLS-mediated lesion bypass functioning to curtail the interaction of Pol η with PCNA at damaged DNA to prevent harmful mutagenesis.

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.

Conservation of DNA damage tolerance pathways from yeast to humans

2007 ◽  
Vol 35 (5) ◽  
pp. 1334-1337 ◽  
Author(s):  
H.D. Ulrich
Keyword(s):  
Damage Tolerance ◽  
Reference Model ◽  
Current Knowledge ◽  
Dna Lesions ◽  
Nuclear Antigen ◽  
Lesion Bypass ◽  
Dna Damage Tolerance ◽  
Experimental Systems ◽  
Species Specific ◽  
Enzymatic Machinery

Damage tolerance mechanisms, which allow the bypass of DNA lesions during replication, are controlled in eukaryotic cells by mono- and poly-ubiquitination of the DNA polymerase cofactor PCNA (proliferating-cell nuclear antigen). In the present review, I will summarize our current knowledge of the enzymatic machinery for ubiquitination of PCNA and the way in which the modifications affect PCNA function during replication and lesion bypass in different organisms. Using the budding yeast as a reference model, I will highlight some of the species-specific differences, but also point out the common principles that emerge from the genetic and biochemical studies of damage tolerance in a range of experimental systems.

scholarly journals Timing matters: error-prone gap filling and translesion synthesis in immunoglobulin gene hypermutation

2008 ◽  
Vol 364 (1517) ◽  
pp. 595-603 ◽  
Author(s):  
Julian E Sale ◽  
Christopher Batters ◽  
Charlotte E Edmunds ◽  
Lara G Phillips ◽  
Laura J Simpson ◽  
...  
Keyword(s):  
Dna Damage ◽  
Active Sites ◽  
Somatic Hypermutation ◽  
Translesion Synthesis ◽  
Dna Lesions ◽  
Immunoglobulin Gene ◽  
Lesion Bypass ◽  
Replication Fork Progression ◽  
Activation Induced Deaminase ◽  
Translesion Polymerases

By temporarily deferring the repair of DNA lesions encountered during replication, the bypass of DNA damage is critical to the ability of cells to withstand genomic insults. Damage bypass can be achieved either by recombinational mechanisms that are generally accurate or by a process called translesion synthesis. Translesion synthesis involves replacing the stalled replicative polymerase with one of a number of specialized DNA polymerases whose active sites are able to tolerate a distorted or damaged DNA template. While this property allows the translesion polymerases to synthesize across damaged bases, it does so with the trade-off of an increased mutation rate. The deployment of these enzymes must therefore be carefully regulated. In addition to their important role in general DNA damage tolerance and mutagenesis, the translesion polymerases play a crucial role in converting the products of activation induced deaminase-catalysed cytidine deamination to mutations during immunoglobulin gene somatic hypermutation. In this paper, we specifically consider the control of translesion synthesis in the context of the timing of lesion bypass relative to replication fork progression and arrest at sites of DNA damage. We then examine how recent observations concerning the control of translesion synthesis might help refine our view of the mechanisms of immunoglobulin gene somatic hypermutation.

scholarly journals Phloretin Ameliorates Testosterone-Induced Benign Prostatic Hyperplasia in Rats by Regulating the Inflammatory Response, Oxidative Stress and Apoptosis

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 743
Author(s):  
Chao Yu Hsu ◽  
Yi Sheng Lin ◽  
Wei Chun Weng ◽  
Lauren Panny ◽  
Hsiang Lai Chen ◽  
...  
Keyword(s):  
Caspase 3 ◽  
Weight Ratio ◽  
Nuclear Antigen ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Body Weight Ratio ◽  
Proliferative Cell Nuclear Antigen ◽  
Prostate Weight ◽  
Prostatic Enlargement ◽  
Inflammatory Proteins ◽  
Proliferative Cell

The inflammatory process is proposed to be one of the factors to benign prostatic enlargement (BPH), and this is the first study examining the anti-inflammatory ability of phloretin in treating rats with testosterone-induced BPH. BPH would be induced by testosterone (10 mg/kg/day testosterone subcutaneously for 28 days), and the other groups of rats were treated with phloretin 50 mg/kg/day or 100 mg/kg/day orally (phr50 or phr100 group) after induction. Prostate weight and prostate weight to body weight ratio were significantly reduced in the Phr100 group. Reduced dihydrotestosterone without interfering with 5α-reductase was observed in the phr100 group. In inflammatory proteins, reduced IL-6, IL-8, IL-17, NF-κB, and COX-2 were seen in the phr100 group. In reactive oxygen species, malondialdehyde was reduced, and superoxide dismutase and glutathione peroxidase were elevated in the phr100 group. In apoptotic assessment, elevated cleaved caspase-3 was observed in rats of the phr100 group. Enhanced pro-apoptotic Bax and reduced anti-apoptotic Bc1-2 could be seen in the phr100 group. In histological stains, markedly decreased glandular hyperplasia and proliferative cell nuclear antigen were observed with reduced expression in the phr100 group. Meanwhile, positive cells of terminal deoxynucleotidyl transferase dUTP nick end labeling were increased in the phr100 group. In conclusion, the treatment of phloretin 100 mg/kg/day could ameliorate testosterone-induced BPH.

scholarly journals PCNA Interacts with Indian Mung Bean Yellow Mosaic Virus Rep and Downregulates Rep Activity

2004 ◽  
Vol 78 (21) ◽  
pp. 11890-11903 ◽  
Author(s):  
Basavaraj Bagewadi ◽  
Shoajiang Chen ◽  
Sunil K. Lal ◽  
Nirupam Roy Choudhury ◽  
Sunil K. Mukherjee
Keyword(s):  
Mosaic Virus ◽  
Mung Bean ◽  
Bean Yellow Mosaic Virus ◽  
Yellow Mosaic Virus ◽  
Nuclear Antigen ◽  
Resting Cells ◽  
Rolling Circle Replication ◽  
Proliferative Cell Nuclear Antigen ◽  
Bipartite Genome

ABSTRACT Proliferative cell nuclear antigen (PCNA), a conserved plant protein as well as an important replication factor, is induced in response to geminivirus infection in the resting cells of the phloem tissues. The biochemical role of PCNA in rolling circle replication (RCR) of geminivirus DNA has not been explored in detail. The initiation of RCR of the bipartite genome of a geminivirus, Indian mung bean yellow mosaic virus (IMYMV), is mainly controlled by viral protein Rep (or AL1 or AC1). The role of host PCNA in RCR of IMYMV was revealed by studying the physical and functional interactions between recombinant PCNA and recombinant IMYMV Rep. Pea nuclear PCNA as well as recombinant pea PCNA showed binding to recombinant Rep in experiments involving both affinity chromatography and yeast two-hybrid approaches. The contacting amino acid residues of PCNA seemed to be present throughout a wide region of the trimeric protein, while those of Rep appeared to be localized only in the middle part of the protein. The site-specific nicking-closing activity and the ATPase function of IMYMV Rep were impaired by PCNA. These observations lead to interesting speculations about the control of viral RCR and dynamic profiles of protein-protein interactions at the RCR origin of the geminiviruses.

scholarly journals Postprenylation CAAX Processing Is Required for Proper Localization of Ras but Not Rho GTPases

2005 ◽  
Vol 16 (4) ◽  
pp. 1606-1616 ◽  
Author(s):  
David Michaelson ◽  
Wasif Ali ◽  
Vi K. Chiu ◽  
Martin Bergo ◽  
Joseph Silletti ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Protein Trafficking ◽  
Rho Gtpases ◽  
Ras Proteins ◽  
Rho Proteins ◽  
Carboxyl Methylation ◽  
C Terminus ◽  
Individual Contributions ◽  
The Individual ◽  
And Function

The CAAX motif at the C terminus of most monomeric GTPases is required for membrane targeting because it signals for a series of three posttranslational modifications that include isoprenylation, endoproteolytic release of the C-terminal– AAX amino acids, and carboxyl methylation of the newly exposed isoprenylcysteine. The individual contributions of these modifications to protein trafficking and function are unknown. To address this issue, we performed a series of experiments with mouse embryonic fibroblasts (MEFs) lacking Rce1 (responsible for removal of the –AAX sequence) or Icmt (responsible for carboxyl methylation of the isoprenylcysteine). In MEFs lacking Rce1 or Icmt, farnesylated Ras proteins were mislocalized. In contrast, the intracellular localizations of geranylgeranylated Rho GTPases were not perturbed. Consistent with the latter finding, RhoGDI binding and actin remodeling were normal in Rce1- and Icmt-deficient cells. Swapping geranylgeranylation for farnesylation on Ras proteins or vice versa on Rho proteins reversed the differential sensitivities to Rce1 and Icmt deficiency. These results suggest that postprenylation CAAX processing is required for proper localization of farnesylated Ras but not geranygeranylated Rho proteins.

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