Nsp1 stalls DNA Polymerase α at DNA hairpins.

The human primosome, a four-subunit complex of DNA primase and DNA polymerase alpha (Polα), plays a critical role in DNA replication by initiating RNA and DNA synthesis on both chromosome strands. A recent study has shown that a major virulence factor in the SARS-CoV-2 infection, Nsp1 (non-structural protein 1), forms a stable complex with Polα but does not affect the primosome activity. Here we show that Nsp1 inhibits DNA synthesis across inverted repeats prone to hairpin formation.

Human primosome requires replication protein A when copying DNA with inverted repeats.

The human primosome, a four-subunit complex of primase and DNA polymerase alpha (Polα), initiates DNA synthesis on both chromosome strands by generating chimeric RNA-DNA primers for loading DNA polymerases delta and epsilon (Polε). Replication protein A (RPA) tightly binds to single-stranded DNA strands, protecting them from nucleolytic digestion and unauthorized transactions. We report here that RPA plays a critical role for the human primosome during DNA synthesis across inverted repeats prone to hairpin formation.

EPR investigation of gamma-irradiated FAMOSER drug for DOSIMETRIC purposes.

Exposure to ionizing radiation can also lead to the formation of stable or unstable radicals in the structures of drugs, as in many materials. The concentrations of these radicals may show a linear dependence on the radiation dose exposed. Since drugs are materials that can be found next to or on radiation victims during a possible nuclear or radiological accident, it is very meaningful to determine the Electron Paramagnetic Resonance (EPR) dosimetric properties of stable radicals in their structures.

Structures of human primosome elongation complexes.

The synthesis of RNA-DNA primer by primosome requires coordination between primase and DNA polymerase α subunits, which is accompanied by unknown architectural rearrangements of multiple domains. Using cryogenic electron microscopy, we solved a 3.6 Å human primosome structure caught at an early stage of RNA primer elongation with deoxynucleotides.

Human DNA polymerase α has a strong mutagenic potential at the initial steps of DNA synthesis.

DNA polymerase α (Polα) is essential for DNA replication initiation and makes a notable contribution to genome mutagenesis. The activity and fidelity of Polα during the early steps of DNA replication have not been well studied. Here we show that at the beginning of DNA synthesis, when extending the RNA primer received from primase, Polα is more mutagenic than during the later DNA elongation steps.