Genome‐wide Excision Repair Map of Cyclobutane Pyrimidine Dimers in Arabidopsis and the Roles of CSA1 and CSA2 Proteins in Transcription‐Coupled Repair

Author(s):  
Sezgi Kaya ◽  
Ogun Adebali ◽  
Onur Oztas ◽  
Aziz Sancar
2020 ◽  
Vol 295 (50) ◽  
pp. 17374-17380 ◽  
Author(s):  
Christopher P. Selby ◽  
Laura A. Lindsey-Boltz ◽  
Yanyan Yang ◽  
Aziz Sancar

In nucleotide excision repair, bulky DNA lesions such as UV-induced cyclobutane pyrimidine dimers are removed from the genome by concerted dual incisions bracketing the lesion, followed by gap filling and ligation. So far, two dual-incision patterns have been discovered: the prokaryotic type, which removes the damage in 11–13-nucleotide-long oligomers, and the eukaryotic type, which removes the damage in 24–32-nucleotide-long oligomers. However, a recent study reported that the UvrC protein of Mycobacterium tuberculosis removes damage in a manner analogous to yeast and humans in a 25-mer oligonucleotide arising from incisions at 15 nt from the 3´ end and 9 nt from the 5´ end flanking the damage. To test this model, we used the in vivo excision assay and the excision repair sequencing genome-wide repair mapping method developed in our laboratory to determine the repair pattern and genome-wide repair map of Mycobacterium smegmatis. We find that M. smegmatis, which possesses homologs of the Escherichia coli uvrA, uvrB, and uvrC genes, removes cyclobutane pyrimidine dimers from the genome in a manner identical to the prokaryotic pattern by incising 7 nt 5´ and 3 or 4 nt 3´ to the photoproduct, and performs transcription-coupled repair in a manner similar to E. coli.


2018 ◽  
Vol 115 (15) ◽  
pp. E3408-E3415 ◽  
Author(s):  
Wentao Li ◽  
Ogun Adebali ◽  
Yanyan Yang ◽  
Christopher P. Selby ◽  
Aziz Sancar

We have adapted the eXcision Repair-sequencing (XR-seq) method to generate single-nucleotide resolution dynamic repair maps of UV-induced cyclobutane pyrimidine dimers and (6-4) pyrimidine–pyrimidone photoproducts in the Saccharomyces cerevisiae genome. We find that these photoproducts are removed from the genome primarily by incisions 13–18 nucleotides 5′ and 6–7 nucleotides 3′ to the UV damage that generate 21- to 27-nt-long excision products. Analyses of the excision repair kinetics both in single genes and at the genome-wide level reveal strong transcription-coupled repair of the transcribed strand at early time points followed by predominantly nontranscribed strand repair at later stages. We have also characterized the excision repair level as a function of the transcription level. The availability of high-resolution and dynamic repair maps should aid in future repair and mutagenesis studies in this model organism.


Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1466 ◽  
Author(s):  
Barbara N. Borsos ◽  
Hajnalka Majoros ◽  
Tibor Pankotai

Nucleotide excision repair (NER) is a versatile DNA repair pathway which can be activated in response to a broad spectrum of UV-induced DNA damage, such as bulky adducts, including cyclobutane-pyrimidine dimers (CPDs) and 6–4 photoproducts (6–4PPs). Based on the genomic position of the lesion, two sub-pathways can be defined: (I) global genomic NER (GG-NER), involved in the ablation of damage throughout the whole genome regardless of the transcription activity of the damaged DNA locus, and (II) transcription-coupled NER (TC-NER), activated at DNA regions where RNAPII-mediated transcription takes place. These processes are tightly regulated by coordinated mechanisms, including post-translational modifications (PTMs). The fine-tuning modulation of the balance between the proteins, responsible for PTMs, is essential to maintain genome integrity and to prevent tumorigenesis. In this review, apart from the other substantial PTMs (SUMOylation, PARylation) related to NER, we principally focus on reversible ubiquitylation, which involves E3 ubiquitin ligase and deubiquitylase (DUB) enzymes responsible for the spatiotemporally precise regulation of NER.


2021 ◽  
Vol 7 (31) ◽  
pp. eabi6508
Author(s):  
Seung-Gi Jin ◽  
Dean Pettinga ◽  
Jennifer Johnson ◽  
Peipei Li ◽  
Gerd P. Pfeifer

Sunlight-associated melanomas carry a unique C-to-T mutation signature. UVB radiation induces cyclobutane pyrimidine dimers (CPDs) as the major form of DNA damage, but the mechanism of how CPDs cause mutations is unclear. To map CPDs at single-base resolution genome wide, we developed the circle damage sequencing (circle-damage-seq) method. In human cells, CPDs form preferentially in a tetranucleotide sequence context (5′-Py-T<>Py-T/A), but this alone does not explain the tumor mutation patterns. To test whether mutations arise at CPDs by cytosine deamination, we specifically mapped UVB-induced cytosine-deaminated CPDs. Transcription start sites (TSSs) were protected from CPDs and deaminated CPDs, but both lesions were enriched immediately upstream of the TSS, suggesting a mutation-promoting role of bound transcription factors. Most importantly, the genomic dinucleotide and trinucleotide sequence specificity of deaminated CPDs matched the prominent mutation signature of melanomas. Our data identify the cytosine-deaminated CPD as the leading premutagenic lesion responsible for mutations in melanomas.


2003 ◽  
Vol 31 (3) ◽  
pp. 694-698 ◽  
Author(s):  
S. McCready ◽  
L. Marcello

Halobacterium is one of the few known Archaea that tolerates high levels of sunlight in its natural environment. Photoreactivation is probably its most important strategy for surviving UV irradiation and we have shown that both of the major UV photoproducts, cyclobutane pyrimidine dimers (CPDs) and (6–4) photoproducts, can be very efficiently repaired by photoreactivation in this organism. There are two putative photolyase gene homologues in the published genome sequence of Halobacterium sp. NRC-1. We have made a mutant deleted in one of these, phr2, and confirmed that this gene codes for a CPD photolyase. (6–4) photoproducts are still photoreactivated in the mutant so we are currently establishing whether the other homologue, phr1, codes for a (6–4) photolyase. We have also demonstrated an excision repair capacity that operates in the absence of visible light but the nature of this pathway is not yet known. There is probably a bacteria-type excision-repair mechanism, since homologues of uvrA, uvrB, uvrC and uvrD have been identified in the Halobacterium genome. However, there are also homologues of eukaryotic nucleotide-excision-repair genes (Saccharomy cescerevisiae RAD3, RAD25 and RAD2) so there may be multiple repair mechanisms for UV damage in Halobacterium.


1995 ◽  
Vol 15 (8) ◽  
pp. 4572-4577 ◽  
Author(s):  
G A Freyer ◽  
S Davey ◽  
J V Ferrer ◽  
A M Martin ◽  
D Beach ◽  
...  

DNA lesions induced by UV light, cyclobutane pyrimidine dimers, and (6-4)pyrimidine pyrimidones are known to be repaired by the process of nucleotide excision repair (NER). However, in the fission yeast Schizosaccharomyces pombe, studies have demonstrated that at least two mechanisms for excising UV photo-products exist; NER and a second, previously unidentified process. Recently we reported that S. pombe contains a DNA endonuclease, SPDE, which recognizes and cleaves at a position immediately adjacent to cyclobutane pyrimidine dimers and (6-4)pyrimidine pyrimidones. Here we report that the UV-sensitive S. pombe rad12-502 mutant lacks SPDE activity. In addition, extracts prepared from the rad12-502 mutant are deficient in DNA excision repair, as demonstrated in an in vitro excision repair assay. DNA repair activity was restored to wild-type levels in extracts prepared from rad12-502 cells by the addition of partially purified SPDE to in vitro repair reaction mixtures. When the rad12-502 mutant was crossed with the NER rad13-A mutant, the resulting double mutant was much more sensitive to UV radiation than either single mutant, demonstrating that the rad12 gene product functions in a DNA repair pathway distinct from NER. These data directly link SPDE to this alternative excision repair process. We propose that the SPDE-dependent DNA repair pathway is the second DNA excision repair process present in S. pombe.


Sign in / Sign up

Export Citation Format

Share Document