scholarly journals Role of the Escherichia coli Nucleotide Excision Repair Proteins in DNA Replication

2000 ◽  
Vol 182 (20) ◽  
pp. 5706-5714 ◽  
Author(s):  
Geri F. Moolenaar ◽  
Celine Moorman ◽  
Nora Goosen

ABSTRACT DNA polymerase I (PolI) functions both in nucleotide excision repair (NER) and in the processing of Okazaki fragments that are generated on the lagging strand during DNA replication.Escherichia coli cells completely lacking the PolI enzyme are viable as long as they are grown on minimal medium. Here we show that viability is fully dependent on the presence of functional UvrA, UvrB, and UvrD (helicase II) proteins but does not require UvrC. In contrast, ΔpolA cells grow even better when theuvrC gene has been deleted. Apparently UvrA, UvrB, and UvrD are needed in a replication backup system that replaces the PolI function, and UvrC interferes with this alternative replication pathway. With specific mutants of UvrC we could show that the inhibitory effect of this protein is related to its catalytic activity that on damaged DNA is responsible for the 3′ incision reaction. Specific mutants of UvrA and UvrB were also studied for their capacity to support the PolI-independent replication. Deletion of the UvrC-binding domain of UvrB resulted in a phenotype similar to that caused by deletion of the uvrC gene, showing that the inhibitory incision activity of UvrC is mediated via binding to UvrB. A mutation in the N-terminal zinc finger domain of UvrA does not affect NER in vivo or in vitro. The same mutation, however, does give inviability in combination with the ΔpolA mutation. Apparently the N-terminal zinc-binding domain of UvrA has specifically evolved for a function outside DNA repair. A model for the function of the UvrA, UvrB, and UvrD proteins in the alternative replication pathway is discussed.

1999 ◽  
Vol 10 (7) ◽  
pp. 2119-2129 ◽  
Author(s):  
Marcus P. Cooper ◽  
Adayabalam S. Balajee ◽  
Vilhelm A. Bohr

The protein p21Cip1, Waf1, Sdi1 is a potent inhibitor of cyclin-dependent kinases (CDKs). p21 can also block DNA replication through its interaction with the proliferating cell nuclear antigen (PCNA), which is an auxiliary factor for polymerase δ. PCNA is also implicated in the repair resynthesis step of nucleotide excision repair (NER). Previous studies have yielded contradictory results on whether p21 regulates NER through its interaction with PCNA. Resolution of this controversy is of interest because it would help understand how DNA repair and replication are regulated. Hence, we have investigated the effect of p21 on NER both in vitro and in vivo using purified fragments of p21 containing either the CDK-binding domain (N terminus) or the PCNA binding domain (C terminus) of the protein. In the in vitro studies, DNA repair synthesis was measured in extracts from normal human fibroblasts using plasmids damaged by UV irradiation. In the in vivo studies, we used intact and permeabilized cells. The results show that the C terminus of the p21 protein inhibits NER both in vitro and in vivo. These are the first in vivo studies in which this question has been examined, and we demonstrate that inhibition of NER by p21 is not merely an artificial in vitro effect. A 50% inhibition of in vitro NER occurred at a 50:1 molar ratio of p21 C-terminus fragment to PCNA monomer. p21 differentially regulates DNA repair and replication, with repair being much less sensitive to inhibition than replication. Our in vivo results suggest that the inhibition occurs at the resynthesis step of the repair process. It also appears that preassembly of PCNA at repair sites mitigates the inhibitory effect of p21. We further demonstrate that the inhibition of DNA repair is mediated via binding of p21 to PCNA. The N terminus of p21 had no effect on DNA repair, and the inhibition of DNA repair by the C terminus of p21 was relieved by the addition of purified PCNA protein.


2013 ◽  
Vol 288 (29) ◽  
pp. 20918-20926 ◽  
Author(s):  
Jinchuan Hu ◽  
Jun-Hyuk Choi ◽  
Shobhan Gaddameedhi ◽  
Michael G. Kemp ◽  
Joyce T. Reardon ◽  
...  

Nucleotide excision repair is the sole mechanism for removing the major UV photoproducts from genomic DNA in human cells. In vitro with human cell-free extract or purified excision repair factors, the damage is removed from naked DNA or nucleosomes in the form of 24- to 32-nucleotide-long oligomers (nominal 30-mer) by dual incisions. Whether the DNA damage is removed from chromatin in vivo in a similar manner and what the fate of the excised oligomer was has not been known previously. Here, we demonstrate that dual incisions occur in vivo identical to the in vitro reaction. Further, we show that transcription-coupled repair, which operates in the absence of the XPC protein, also generates the nominal 30-mer in UV-irradiated XP-C mutant cells. Finally, we report that the excised 30-mer is released from the chromatin in complex with the repair factors TFIIH and XPG. Taken together, our results show the congruence of in vivo and in vitro data on nucleotide excision repair in humans.


2007 ◽  
Vol 169 (2) ◽  
pp. 134
Author(s):  
N. Güngör ◽  
R.W.L. Godschalk ◽  
D. Pachen ◽  
A. Haegens ◽  
F.J. Van Schooten ◽  
...  

2012 ◽  
Vol 199 (2) ◽  
pp. 235-249 ◽  
Author(s):  
Alex Pines ◽  
Mischa G. Vrouwe ◽  
Jurgen A. Marteijn ◽  
Dimitris Typas ◽  
Martijn S. Luijsterburg ◽  
...  

The WD40-repeat protein DDB2 is essential for efficient recognition and subsequent removal of ultraviolet (UV)-induced DNA lesions by nucleotide excision repair (NER). However, how DDB2 promotes NER in chromatin is poorly understood. Here, we identify poly(ADP-ribose) polymerase 1 (PARP1) as a novel DDB2-associated factor. We demonstrate that DDB2 facilitated poly(ADP-ribosyl)ation of UV-damaged chromatin through the activity of PARP1, resulting in the recruitment of the chromatin-remodeling enzyme ALC1. Depletion of ALC1 rendered cells sensitive to UV and impaired repair of UV-induced DNA lesions. Additionally, DDB2 itself was targeted by poly(ADP-ribosyl)ation, resulting in increased protein stability and a prolonged chromatin retention time. Our in vitro and in vivo data support a model in which poly(ADP-ribosyl)ation of DDB2 suppresses DDB2 ubiquitylation and outline a molecular mechanism for PARP1-mediated regulation of NER through DDB2 stabilization and recruitment of the chromatin remodeler ALC1.


2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Kelley N. Newton ◽  
Charmain T. Courcelle ◽  
Justin Courcelle

UvrD is a DNA helicase that participates in nucleotide excision repair and several replication-associated processes, including methyl-directed mismatch repair and recombination. UvrD is capable of displacing oligonucleotides from synthetic forked DNA structuresin vitroand is essential for viability in the absence of Rep, a helicase associated with processing replication forks. These observations have led others to propose that UvrD may promote fork regression and facilitate resetting of the replication fork following arrest. However, the molecular activity of UvrD at replication forksin vivohas not been directly examined. In this study, we characterized the role UvrD has in processing and restoring replication forks following arrest by UV-induced DNA damage. We show that UvrD is required for DNA synthesis to recover. However, in the absence of UvrD, the displacement and partial degradation of the nascent DNA at the arrested fork occur normally. In addition, damage-induced replication intermediates persist and accumulate inuvrDmutants in a manner that is similar to that observed in other nucleotide excision repair mutants. These data indicate that, following arrest by DNA damage, UvrD is not required to catalyze fork regressionin vivoand suggest that the failure ofuvrDmutants to restore DNA synthesis following UV-induced arrest relates to its role in nucleotide excision repair.


2017 ◽  
Vol 38 (10) ◽  
pp. 976-985 ◽  
Author(s):  
Chunhua Han ◽  
Ran Zhao ◽  
John Kroger ◽  
Jinshan He ◽  
Gulzar Wani ◽  
...  

Abstract Subunit 2 of DNA damage-binding protein complex (DDB2) is an early sensor of nucleotide excision repair (NER) pathway for eliminating DNA damage induced by UV radiation (UVR) and cisplatin treatments of mammalian cells. DDB2 is modified by ubiquitin and poly(ADP-ribose) (PAR) in response to UVR, and these modifications play a crucial role in regulating NER. Here, using immuno-analysis of irradiated cell extracts, we have identified multiple post-irradiation modifications of DDB2 protein. Interestingly, although the DNA lesions induced by both UVR and cisplatin are corrected by NER, only the UV irradiation, but not the cisplatin treatment, induces any discernable DDB2 modifications. We, for the first time, show that the appearance of UVR-induced DDB2 modifications depend on the binding of DDB2 to the damaged chromatin and the participation of functionally active 26S proteasome. The in vitro and in vivo analysis revealed that SUMO-1 conjugations comprise a significant portion of these UVR-induced DDB2 modifications. Mapping of SUMO-modified sites demonstrated that UVR-induced SUMOylation occurs on Lys-309 residue of DDB2 protein. Mutation of Lys-309 to Arg-309 diminished the DDB2 SUMOylation observable both in vitro and in vivo. Moreover, K309R mutated DDB2 lost its function of recruiting XPC to the DNA damage sites, as well as the ability to repair cyclobutane pyrimidine dimers following cellular UV irradiation. Taken together, our results indicate that DDB2 is modified by SUMOylation upon UV irradiation, and this post-translational modification plays an important role in the initial recognition and processing of UVR-induced DNA damage occurring within the context of chromatin.


2008 ◽  
Vol 179 (4S) ◽  
pp. 373-373
Author(s):  
Ingo Kausch ◽  
Andreas Albers ◽  
Beate Thode ◽  
Christian Doehn ◽  
Dieter Jocham

1989 ◽  
Vol 9 (11) ◽  
pp. 4767-4776
Author(s):  
G B Sancar ◽  
F W Smith

The PHR1 gene of Saccharomyces cerevisiae encodes a DNA photolyase that catalyzes the light-dependent repair of pyrimidine dimers. In the absence of photoreactivating light, this enzyme binds to pyrimidine dimers but is unable to repair them. We have assessed the effect of bound photolyase on the dark survival of yeast cells carrying mutations in genes that eliminate either nucleotide excision repair (RAD2) or mutagenic repair (RAD18). We found that a functional PHR1 gene enhanced dark survival in a rad18 background but failed to do so in a rad2 or rad2 rad18 background and therefore conclude that photolyase stimulates specifically nucleotide excision repair of dimers in S. cerevisiae. This effect is similar to the effect of Escherichia coli photolyase on excision repair in the bacterium. However, despite the functional and structural similarities between yeast photolyase and the E. coli enzyme and complementation of the photoreactivation deficiency of E. coli phr mutants by PHR1, yeast photolyase failed to enhance excision repair in the bacterium. Instead, Phr1 was found to be a potent inhibitor of dark repair in recA strains but had no effect in uvrA strains. The results of in vitro experiments indicate that inhibition of nucleotide excision repair results from competition between yeast photolyase and ABC excision nuclease for binding at pyrimidine dimers. In addition, the A and B subunits of the excision nuclease, when allowed to bind to dimers before photolyase, suppressed photoreactivation by Phr1. We propose that enhancement of nucleotide excision repair by photolyases is a general phenomenon and that photolyase should be considered an accessory protein in this pathway.


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