Plant DNA Polymerases

Abstract

Maintenance of genome integrity is a key process in all organisms. DNA polymerases (Pols) are central players in this process as they are in charge of the faithful reproduction of the genetic information, as well as of DNA repair. Interestingly, all eukaryotes possess a large repertoire of polymerases. Three protein complexes, DNA Pol α, δ, and ε, are in charge of nuclear DNA replication. These enzymes have the fidelity and processivity required to replicate long DNA sequences, but DNA lesions can block their progression. Consequently, eukaryotic genomes also encode a variable number of specialized polymerases (between five and 16 depending on the organism) that are involved in the replication of damaged DNA, DNA repair, and organellar DNA replication. This diversity of enzymes likely stems from their ability to bypass specific types of lesions. In the past 10–15 years, our knowledge regarding plant DNA polymerases dramatically increased. In this review, we discuss these recent findings and compare acquired knowledge in plants to data obtained in other eukaryotes. We also discuss the emerging links between genome and epigenome replication.

Mitotic Inheritance of PRC2-Mediated Silencing: Mechanistic Insights and Developmental Perspectives

“…Thus, loss of interaction between PRC2 and EARLY IN SHORT DAYS (ESD7), the catalytic subunit of DNA polymerase epsilon (Pol-ε), results in the misexpression of major flowering time regulators such as AGAMOUS (AG), SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1), and FLOWERING LOCUS T (FT) (del Olmo et al, 2010(del Olmo et al, , 2016, whose expression is controlled by PRC2. Loss of other DNA polymerases including Pol-α INCURVATA2 (ICU2) and Pol-δ POLD2 also impacts on H3K27me3 distribution, though a direct link with PRC2 subunits remains to be demonstrated (Pedroza-Garcia et al, 2019). These results provide evidence that interactions of PRC2 with multiple DNA polymerases acting at the replication fork likely play a significant role in the maintenance of H3K27me3 landscapes in plants.…”

The Dark Side of UV-Induced DNA Lesion Repair

“…Duplication of nuclear DNA in eukaryotes is dependent on a multi-protein replication complex including pol α with the associated primase activity and two replicases, pol δ and pol ε. A replication complex bound to DNA forms a replication fork whose movement is sensitive to mutations in the template DNA generated by UV light [220]. Unrepaired DNA lesions including pyrimidine dimers may effectively block the synthesis of a new DNA strand throughout stalling of the replication fork [221].…”

“…DDT may occur by two distinct mechanisms [223,224]. Whereas the first is based on TLS [220], the other is dependent on template switching [225]. DDT studies on a yeast model have indicated that the choice between TLS and the template switching mechanism is controlled by ubiquitination of PCNA in response to encountered DNA damage during DNA replication [223].…”

“…Similarly to other eukaryotes, Arabidopsis has several TLS pols including AtREV1, AtPOLη, AtPOLλ, AtPOLκ, AtPOLθ and AtPOLζ composed of AtREV3 (DNA polymerase ζ catalytic subunit) and AtREV7 (DNA polymerase ζ processivity subunit) [220]. Studies of AtREV1, AtPOLη, AtPOLζ gene function deficient mutants have shown the involvement of these gene products in the Arabidopsis response to UV [232][233][234].…”

Plant Organellar DNA Polymerases Evolved Multifunctionality through the Acquisition of Novel Amino Acid Insertions

“…In most organisms, the main DNA polymerase in charge of BER-SP is DNA polymerase [ 72 ]. However, this polymerase is absent in plants [ 73 ]. On the other hand, BER-LP requires a specialized DNAP with strand-displacement activity, that incorporates several nucleotides (10–12 bases) after the processed AP site.…”