scholarly journals The Influence of (5′R)- and (5′S)-5′,8-Cyclo-2′-Deoxyadenosine on UDG and hAPE1 Activity. Tandem Lesions are the Base Excision Repair System’s Nightmare

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1303 ◽  
Author(s):  
Karwowski

DNA lesions are formed continuously in each living cell as a result of environmental factors, ionisation radiation, metabolic processes, etc. Most lesions are removed from the genome by the base excision repair system (BER). The activation of the BER protein cascade starts with DNA damage recognition by glycosylases. Uracil-DNA glycosylase (UDG) is one of the most evolutionary preserved glycosylases which remove the frequently occurring 2′-deoxyuridine from single (ss) and double-stranded (ds) oligonucleotides. Conversely, the unique tandem lesions (5′R)- and (5′S)-5′,8-cyclo-2′-deoxyadenosine (cdA) are not suitable substrates for BER machinery and are released from the genome by the nucleotide excision repair (NER) system. However, the cyclopurines appearing in a clustered DNA damage structure can influence the BER process of other lesions like dU. In this article, UDG inhibition by 5′S- and 5′R-cdA is shown and discussed in an experimental and theoretical manner. This phenomenon was observed when a tandem lesion appears in single or double-stranded oligonucleotides next to dU, on its 3′-end side. The cdA shift to the 5′-end side of dU in ss-DNA stops this effect in both cdA diastereomers. Surprisingly, in the case of ds-DNA, 5′S-cdA completely blocks uracil excision by UDG. Conversely, 5′R-cdA allows glycosylase for uracil removal, but the subsequently formed apurinic/apyrimidinic (AP) site is not suitable for human AP-site endonuclease 1 (hAPE1) activity. In conclusion, the appearance of the discussed tandem lesion in the structure of single or double-stranded DNA can stop the entire base repair process at its beginning, which due to UDG and hAPE1 inhibition can lead to mutagenesis. On the other hand, the presented results can cast some light on the UDG or hAPE1 inhibitors being used as a potential treatment.

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5177
Author(s):  
Michał Szewczuk ◽  
Karolina Boguszewska ◽  
Julia Kaźmierczak-Barańska ◽  
Bolesław T. Karwowski

Ionizing radiation is a factor that seriously damages cellular mechanisms/macromolecules, e.g., by inducing damage in the human genome, such as 5′,8-cyclo-2′-deoxypurines (cdPus). CdPus may become a component of clustered DNA lesions (CDL), which are notably unfavorable for the base excision repair system (BER). In this study, the influence of 5′S and 5′R diastereomers of 5′,8-cyclo-2′-deoxyadenosine (cdA) and 5′,8-cyclo-2′-deoxyguanosine (cdG) on the uracil-DNA glycosylase (UDG) and human AP site endonuclease 1 (hAPE1) activity has been taken under consideration. Synthetic oligonucleotides containing 2′-deoxyuridine (dU) and cdPu were used as a model of single-stranded CDL. The activity of the UDG and hAPE1 enzymes decreased in the presence of RcdG compared to ScdG. Contrary to the above, ScdA reduced enzyme activity more than RcdA. The presented results show the influence of cdPus lesions located within CDL on the activity of the initial stages of BER dependently on their position toward dU. Numerous studies have shown the biological importance of cdPus (e.g., as a risk of carcinogenesis). Due to that, it is important to understand how to recognize and eliminate this type of DNA damage from the genome.


Microbiology ◽  
2005 ◽  
Vol 151 (2) ◽  
pp. 557-567 ◽  
Author(s):  
Akamol E. Suvarnapunya ◽  
Murry A. Stein

Reactive oxidants are a primary weapon of the macrophage antibacterial arsenal. The ability of virulent Salmonella to repair oxidative DNA lesions via the base-excision repair system (BER) enables its survival and replication within the macrophage, but is not required for extracellular growth. Salmonella also inhibits the targeting of oxidant generators to the Salmonella-containing vacuole (SCV) via Salmonella Pathogenicity Island 2 (SPI2). Accordingly, the relative contributions of these two discrete systems to Salmonella resistance to both oxidative mutagenesis and lethality within RAW 264.7 macrophages were investigated. A mutant unable to initiate BER was constructed by deleting all three BER bifunctional glycosylases (Δfpg/nth/nei), and was significantly impaired for early intramacrophage survival. Mutations in various SPI2 effector (sifA and sseEFG) and structural (ssaV) genes were then analysed in the BER mutant background. Loss of SPI2 function alone appeared to increase macrophage-induced mutation. Statistical analyses of the reduced intramacrophage survival of SPI2 mutants and the corresponding SPI2/BER mutants indicated a synergistic interaction between BER and SPI2, suggesting that SPI2 promotes intramacrophage survival by protecting Salmonella DNA from exposure to macrophage oxidants. Furthermore, this protection may involve the SseF and SseG effectors. In contrast, the SifA effector did not seem to play a major role in oxidant protection. It is speculated that Salmonella initially stalls oxidative killing by preserving its genomic integrity through the function of BER, until it can upregulate SPI2 to limit its exposure to macrophage oxidants.


2009 ◽  
Vol 5 (5) ◽  
pp. e1000451 ◽  
Author(s):  
Anthony R. Richardson ◽  
Khanh C. Soliven ◽  
Margaret E. Castor ◽  
Penelope D. Barnes ◽  
Stephen J. Libby ◽  
...  

Author(s):  
Yeldar Baiken ◽  
Damira Kanayeva ◽  
Sabira Taipakova ◽  
Regina Groisman ◽  
Alexander A. Ishchenko ◽  
...  

Chemical alterations in DNA induced by genotoxic factors can have a complex nature such as bulky DNA adducts, interstrand DNA cross-links (ICLs), and clustered DNA lesions (including double-strand breaks, DSB). Complex DNA damage (CDD) has a complex character/structure as compared to singular lesions like randomly distributed abasic sites, deaminated, alkylated, and oxidized DNA bases. CDD is thought to be critical since they are more challenging to repair than singular lesions. Although CDD naturally constitutes a relatively minor fraction of the overall DNA damage induced by free radicals, DNA cross-linking agents, and ionizing radiation, if left unrepaired, these lesions cause a number of serious consequences, such as gross chromosomal rearrangements and genome instability. If not tightly controlled, the repair of ICLs and clustered bi-stranded oxidized bases via DNA excision repair will either inhibit initial steps of repair or produce persistent chromosomal breaks and consequently be lethal for the cells. Biochemical and genetic evidences indicate that the removal of CDD requires concurrent involvement of a number of distinct DNA repair pathways including poly(ADP-ribose) polymerase (PARP)-mediated DNA strand break repair, base excision repair (BER), nucleotide incision repair (NIR), global genome and transcription coupled nucleotide excision repair (GG-NER and TC-NER, respectively), mismatch repair (MMR), homologous recombination (HR), non-homologous end joining (NHEJ), and translesion DNA synthesis (TLS) pathways. In this review, we describe the role of DNA glycosylase-mediated BER pathway in the removal of complex DNA lesions.


2017 ◽  
Vol 36 (7) ◽  
pp. 535-540 ◽  
Author(s):  
Piotr Czarny ◽  
Anna Merecz-Sadowska ◽  
Kinga Majchrzak ◽  
Maciej Jabłkowski ◽  
Janusz Szemraj ◽  
...  

2020 ◽  
Vol 21 (18) ◽  
pp. 6600
Author(s):  
Nicola Winkelbeiner ◽  
Viktoria K. Wandt ◽  
Franziska Ebert ◽  
Kristina Lossow ◽  
Ezgi E. Bankoglu ◽  
...  

Investigation of processes that contribute to the maintenance of genomic stability is one crucial factor in the attempt to understand mechanisms that facilitate ageing. The DNA damage response (DDR) and DNA repair mechanisms are crucial to safeguard the integrity of DNA and to prevent accumulation of persistent DNA damage. Among them, base excision repair (BER) plays a decisive role. BER is the major repair pathway for small oxidative base modifications and apurinic/apyrimidinic (AP) sites. We established a highly sensitive non-radioactive assay to measure BER incision activity in murine liver samples. Incision activity can be assessed towards the three DNA lesions 8-oxo-2’-deoxyguanosine (8-oxodG), 5-hydroxy-2’-deoxyuracil (5-OHdU), and an AP site analogue. We applied the established assay to murine livers of adult and old mice of both sexes. Furthermore, poly(ADP-ribosyl)ation (PARylation) was assessed, which is an important determinant in DDR and BER. Additionally, DNA damage levels were measured to examine the overall damage levels. No impact of ageing on the investigated endpoints in liver tissue were found. However, animal sex seems to be a significant impact factor, as evident by sex-dependent alterations in all endpoints investigated. Moreover, our results revealed interrelationships between the investigated endpoints indicative for the synergetic mode of action of the cellular DNA integrity maintaining machinery.


2012 ◽  
Vol 124 (42) ◽  
pp. 10684-10688
Author(s):  
Hui Xu ◽  
Wei Huang ◽  
Qing-Li He ◽  
Zhi-Xiong Zhao ◽  
Feng Zhang ◽  
...  

2016 ◽  
Vol 41 (3-4) ◽  
pp. 152-171 ◽  
Author(s):  
Dominik Kwiatkowski ◽  
Piotr Czarny ◽  
Monika Toma ◽  
Natalia Jurkowska ◽  
Agnieszka Sliwinska ◽  
...  

Background: Increased oxidative damage to DNA is one of the pathways involved in Alzheimer's disease (AD). Insufficient base excision repair (BER) is in part responsible for increased oxidative DNA damage. The aim of the present study was to assess the effect of polymorphic variants of BER-involved genes and the peripheral markers of DNA damage and repair in patients with AD. Material and Methods: Comet assays and TaqMan probes were used to assess DNA damage, BER efficiency and polymorphic variants of 12 BER genes in blood samples from 105 AD patients and 130 controls. The DNA repair efficacy (DRE) was calculated according to a specific equation. Results: The levels of endogenous and oxidative DNA damages were higher in AD patients than controls. The polymorphic variants of XRCC1 c.580C>T XRCC1 c.1196A>G and OGG1 c.977C>G are associated with increased DNA damage in AD. Conclusion: Our results show that oxidative stress and disturbances in DRE are particularly responsible for the elevated DNA lesions in AD. The results suggest that oxidative stress and disruption in DNA repair may contribute to increased DNA damage in AD patients and risk of this disease. In addition, disturbances in DRE may be associated with polymorphisms of OGG1 and XRCC1.


Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 725
Author(s):  
Karolina Boguszewska ◽  
Michał Szewczuk ◽  
Julia Kaźmierczak-Barańska ◽  
Bolesław T. Karwowski

The clustered DNA lesions (CDLs) are a characteristic feature of ionizing radiation’s impact on the human genetic material. CDLs impair the efficiency of cellular repair machinery, especially base excision repair (BER). When CDLs contain a lesion repaired by BER (e.g., apurinic/apyrimidinic (AP) sites) and a bulkier 5′,8-cyclo-2′-deoxypurine (cdPu), which is not a substrate for BER, the repair efficiency of the first one may be affected. The cdPus’ influence on the efficiency of nuclear BER in xrs5 cells have been investigated using synthetic oligonucleotides with bi-stranded CDL (containing (5′S) 5′,8-cyclo-2′-deoxyadenosine (ScdA), (5′R) 5′,8-cyclo-2′-deoxyadenosine (RcdA), (5′S) 5′,8-cyclo-2′-deoxyguanosine (ScdG) or (5′R) 5′,8-cyclo-2′-deoxyguanosine (RcdG) in one strand and an AP site in the other strand at different interlesion distances). Here, for the first time, the impact of ScdG and RcdG was experimentally tested in the context of nuclear BER. This study shows that the presence of RcdA inhibits BER more than ScdA; however, ScdG decreases repair level more than RcdG. Moreover, AP sites located ≤10 base pairs to the cdPu on its 5′-end side were repaired less efficiently than AP sites located ≤10 base pairs on the 3′-end side of cdPu. The strand with an AP site placed opposite cdPu or one base in the 5′-end direction was not reconstituted for cdA nor cdG. CdPus affect the repair of the other lesion within the CDL. It may translate to a prolonged lifetime of unrepaired lesions leading to mutations and impaired cellular processes. Therefore, future research should focus on exploring this subject in more detail.


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