Abstract
Proliferating cell nuclear antigen (PCNA) is an essential protein for DNA replication, DNA repair, cell cycle regulation, chromatin remodeling, and epigenetics. Many proteins interact with PCNA through the PCNA interacting peptide (PIP)-box or the newly identified AlkB homolog 2 PCNA interacting motif (APIM). The xeroderma pigmentosum group A (XPA) protein, with a central but somewhat elusive role in nucleotide excision repair (NER), contains the APIM sequence suggesting an interaction with PCNA. With an in vivo based approach, using modern techniques in live human cells, we show that APIM in XPA is a functional PCNA interacting motif and that efficient NER of UV lesions is dependent on an intact APIM sequence in XPA. We show that XPA−/− cells complemented with XPA containing a mutated APIM sequence have increased UV sensitivity, reduced repair of cyclobutane pyrimidine dimers and (6–4) photoproducts, and are consequently more arrested in S phase as compared to XPA−/− cells complemented with wild type XPA. Notably, XPA colocalizes with PCNA in replication foci and is loaded on newly synthesized DNA in undamaged cells. In addition, the TFIIH subunit XPD, as well as XPF are loaded on DNA together with XPA, and XPC and XPG colocalize with PCNA in replication foci. Altogether, our results suggest a presence of the NER complex in the vicinity of the replisome and a novel role of NER in post-replicative repair.
Highlights
Proper repair of DNA is vital in order to avoid mutations that may cause cancer and other diseases
In this study we show for the first time that Xeroderma pigmentosum group A (XPA) directly interacts with Proliferating cell nuclear antigen (PCNA) via its AlkB homolog PCNA interacting motif (APIM) sequence, an interaction required for optimal Nucleotide excision repair (NER)
Localization of XPA in replication foci was somewhat surprising because an association between the NER pathway and the replication machinery has hitherto not been discussed in the literature
Summary
Proper repair of DNA is vital in order to avoid mutations that may cause cancer and other diseases. Xeroderma pigmentosum group A (XPA) is a protein in the Nucleotide excision repair (NER) pathway responsible for removal of a wide range of lesions leading to distortions of the DNA helix, most frequently caused by UV radiation (UVR) from the sun. CPDs, are less efficiently recognized by NER, but are bypassed by the translesion synthesis (TLS) polymerase POLg [11] These bypassed CPDs are believed to be repaired by NER prior to round of replication. Of the many proteins involved in NER, XPA is indispensable due to its central role in the core incision complex where it is suggested to be the rate limiting factor [12]. PCNA is an essential component of NER where it plays a role in mediating repair synthesis after dual incision [29,30]. The presence of NER proteins close to replication forks suggests a novel function of NER in post-replicative repair
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
