Non‐recombinogenic roles for Rad52 in translesion synthesis during DNA damage tolerance

Abstract

DNA damage tolerance relies on homologous recombination (HR) and translesion synthesis (TLS) mechanisms to fill in the ssDNA gaps generated during passing of the replication fork over DNA lesions in the template. Whereas TLS requires specialized polymerases able to incorporate a dNTP opposite the lesion and is error-prone, HR uses the sister chromatid and is mostly error-free. We report that the HR protein Rad52-but not Rad51 and Rad57acts in concert with the TLS machinery (Rad6/Rad18-mediated PCNA ubiquitylation and polymerases Rev1/Pol f) to repair MMS and UV light-induced ssDNA gaps through a non-recombinogenic mechanism, as inferred from the different phenotypes displayed in the absence of Rad52 and Rad54 (essential for MMS-and UVinduced HR); accordingly, Rad52 is required for efficient DNA damage-induced mutagenesis. In addition, Rad52, Rad51, and Rad57, but not Rad54, facilitate Rad6/Rad18 binding to chromatin and subsequent DNA damage-induced PCNA ubiquitylation. Therefore, Rad52 facilitates the tolerance process not only by HR but also by TLS through Rad51/Rad57-dependent and-independent processes, providing a novel role for the recombination proteins in maintaining genome integrity.

Physical interactions between MCM and Rad51 facilitate replication fork lesion bypass and ssDNA gap filling by non-recombinogenic functions

“…One possibility is that these physical interactions provide a platform for the landing of replication and repair factors at the proximity of stressed forks. Recently, we showed that Rad51 and Rad52 have a non-recombinogenic role in TLS by facilitating the recruitment of the Rad6/Rad18 complex to chromatin (Cano-Linares et al, 2021). Proliferating cell nuclear antigen (PCNA) ubiquitylation by Rad6/Rad18 is necessary for the recruitment of TLS polymerases (Bienko et al, 2005) and facilitates replication fork advance in the presence of a damaged template (Ortiz-Bazá n et al, 2014).…”

“…Tagged and deletion strains were constructed by a PCR-based strategy (Longtine et al, 1998). The uSCE system was backcrossed five times into the W303 background (Cano-Linares et al, 2021). The integrative plasmids pRS551-L120A,V181A (a gift from N. Hollingsworth) and pRS306-r51.54 (see Method details) were used to replace CDC7 and RAD51 with cdc7-as3 (W303cdc7as3-2) and rad51m (w303.51.54-7), respectively.…”

“…This process requires multiple recombination factors, including Rad51 and Rad52, and relies on the transient formation of sister chromatid junctions (SCJs) through strand-exchange reactions (Branzei et al, 2008;Liberi et al, 2005;Mankouri et al, 2007;Vanoli et al, 2010). In addition, we have recently shown that Rad51 and Rad52 facilitate TLS through non-recombinogenic functions (Cano-Linares et al, 2021). In S. cerevisiae, the repair of these ssDNA gaps occurs post-replicatively at DNA regions that are spatially separated from replication forks (Gonzá lez-Prieto et al, 2013;Wong et al, 2020).…”

Knockdown of DNA polymerase ζ relieved the chemoresistance of glioma via inhibiting the PI3K/AKT signaling pathway

“…The DNA repair mechanism of tumor cells is a key factor affecting cell chemosensitivity. Recently, studies have shown that translesion DNA synthesis (TLS) is an emergency repair mechanism in eukaryotic cells [8][9][10]. Translesion DNA synthesis plays an important role in the repair of DNA damage induced by ionizing radiation, and therefore enhances the radiation resistance of tumor cells.…”

“…Translesion DNA synthesis plays an important role in the repair of DNA damage induced by ionizing radiation, and therefore enhances the radiation resistance of tumor cells. DNA polymerase ζ (pol ζ) is the key component of TLS [9][10][11][12]. It mainly consists of two subunits, REV3L and REV7.…”