The Rev1-Polζ translesion synthesis mutasome: Structure, interactions and inhibition

Abstract

DNA contains information that must be safeguarded, but also accessed for transcription and replication. To perform replication, eukaryotic cells use the B-family DNA polymerase enzymes Polδ and Polε, which are optimized for accuracy, speed, and processivity. The molecular basis of these high-performance characteristics causes these replicative polymerases to fail at sites of DNA damage (lesions), which would lead to genomic instability and cell death. To avoid this, cells possess additional DNA polymerases such as the Y-family of polymerases and the B-family member Polζ that can replicate over sites of DNA damage in a process called translesion synthesis (TLS). While able to replicate over DNA lesions, the TLS polymerases exhibit low-fidelity on undamaged DNA and, consequently, must be prevented from replicating DNA under normal circumstances and recruited only when necessary. The replicative bypass of most types of DNA lesions requires the consecutive action of these specialized TLS polymerases assembled into a dynamic multiprotein complex called the Rev1/Polζ mutasome. To this end, posttranslational modifications and a network of protein-protein interactions mediated by accessory domains/ subunits of the TLS polymerases control the assembly and rearrangements of the Rev1/Polζ mutasome and recruitment of TLS proteins to sites of DNA damage. This chapter focuses on the structures and interactions that control these processes underlying the function of the Rev1/Polζ mutasome, as well as the development of small molecule inhibitors of the Rev1/Polζ dependent TLS holding promise as a potential anticancer therapy.

Human Rev1 relies on insert-2 to promote selective binding and accurate replication of stabilized G-quadruplex motifs

“…Rev1 acts as a scaffold for recruitment of the other Y-family polymerases, and the Rev1-polζ mutasome is a major source of mutations for eukaryotes ( 45 ). The Rev1 protein-template mechanism of nucleotide selection allows for bypass of abasic sites and other lesions ( 46 ).…”

Structure‐Based Drug Design of Phenazopyridine Derivatives as Inhibitors of Rev1 Interactions in Translesion Synthesis

“…TLS inhibition has recently emerged as a strategy to increase chemotherapeutic sensitivity and avert resistance associated with first‐line platinating and alkylating drugs [9–11] . Rev1′s scaffolding function is essential for TLS [17,21,22] and its inhibition provides a promising avenue for maintaining genotoxic chemotherapy sensitivity in cancer cells [9,29–33] . The RIR interface of Rev1‐CT is an important binding site for the “inserter” TLS polymerases Polι, Polκ, Polη, and the “extender” polymerase Polζ (via its accessory subunit, PolD3) [23–25,28] .…”

“…Translesion synthesis (TLS) is an error‐prone DDT pathway implicated in resistance to platinating and alkylating agents [9–13] . In TLS, mutagenic DNA polymerases, Polη, Polι, Polκ, Rev1, and Polζ, are recruited to copy over DNA lesions that the replicative polymerases, Polδ and Polϵ, are unable to bypass [14–17] . TLS promotes drug resistance by different mechanisms.…”

“…TLS of DNA adducts caused by platinating and alkylating agents is a two‐step process whereby an “inserter” TLS polymerase, Polη, Polκ, or Polι, inserts nucleotides across the site of DNA damage, and then the “extender” polymerase Polζ, copies past the DNA lesion [14–17,20] . The “inserter” and “extender” polymerases are assembled into a multiprotein TLS complex with the aid of the ubiquitinated sliding clamp PCNA and the TLS polymerase Rev1, which play scaffolding roles in TLS by mediating protein‐protein interactions (PPIs) [17,21–22] . For example, the Rev1 C‐terminal domain (Rev1‐CT) binds Rev1‐intracting regions (RIRs) of Polη, Polι, and Polκ, [23–25] and Polζ′s regulatory subunit Rev7 [26] at two independent binding interfaces [27] (Figure 1A).…”

Targeting protein–protein interactions in the DNA damage response pathways for cancer chemotherapy

“…[3][4][5] In addition to repair pathways, the DDR also utilizes DNA 4 damage tolerance (DDT) pathways such as translesion synthesis (TLS), which allows bypass replication over DNA lesions at the price of increased mutagenesis. [16][17][18][19] Alteration or loss of DDR capabilities is a hallmark of many types of cancer, which is often compensated by the use of alternative DDR pathways that can be exploited pharmaceutically to selectively kill cancer cells. [4][5][6][7][8][9][10][11][12][13] Furthermore, genotoxic front-line chemotherapeutics induce DNA damage that can be repaired and/or avoided by specific DDR pathway(s), which can be targeted for the development of adjuvant drugs to enhance efficacy of existing treatments.…”