The cell division cycle must be strictly regulated during both development and adult maintenance, and efficient and well-controlled DNA replication is a key event in the cell cycle. DNA replication origins are prepared in G1 phase of the cell cycle in a process known as origin licensing which is essential for DNA replication initiation in the subsequent S phase. Appropriate origin licensing includes: (1) Licensing enough origins at adequate origin licensing speed to complete licensing before G1 phase ends; (2) Licensing origins such that they are well-distributed on all chromosomes. Both aspects of licensing are critical for replication efficiency and accuracy. In this minireview, we will discuss recent advances in defining how origin licensing speed and distribution are critical to ensure DNA replication completion and genome stability.
Long Terminal Repeat (LTR) retrotransposons replicate through “copy and paste” mechanisms mediated by reverse transcription in virus-like particles (VLPs) and integration in the nucleus (see article from Lee and Martienssen, pp. 2241–2251). VLP DNA-sequencing reveals complementary DNA (cDNA) replication intermediates from active retrotransposons. Instead of functional linear intermediates that integrate in the nucleus, the Arabidopsis retroelement SISYPHUS lacks features important for nuclear import, and instead accumulates circular cDNA from futile autointegration within the VLP. In Greek mythology, Sisyphus was condemned to the futile task of rolling a huge boulder uphill eternally. Image created and provided Seung Cho Lee, Evan Ernst, and Robert A. Martienssen.
Efficiency and equity in origin licensing to ensure complete DNA replication
Liu Mei, Jeanette Gowen Cook; Efficiency and equity in origin licensing to ensure complete DNA replication. Biochem Soc Trans 1 November 2021; 49 (5): 2133–2141. doi: https://doi.org/10.1042/BST20210161
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