# An Insight into the Mechanism of DNA Cleavage by DNA Endonuclease from the Hyperthermophilic Archaeon Pyrococcus furiosus

## TL;DR

This study explores how a DNA-cutting enzyme from a heat-loving archaeon interacts with different DNA substrates and causes structural changes.

## Contribution

The study reveals that the enzyme induces multiple DNA conformational changes through dissimilar kinetic pathways.

## Key findings

- EndoQ induces multiple conformational changes in DNA during binding.
- Different DNA substrates lead to distinct kinetic pathways in enzyme-substrate complex formation.
- These conformational changes likely enable the enzyme to function at extreme temperatures.

## Abstract

Hyperthermophilic archaea such as Pyrococcus furiosus survive under very aggressive environmental conditions by occupying niches inaccessible to representatives of other domains of life. The ability to survive such severe living conditions must be ensured by extraordinarily efficient mechanisms of DNA processing, including repair. Therefore, in this study, we compared kinetics of conformational changes of DNA Endonuclease Q from P. furiosus during its interaction with various DNA substrates containing an analog of an apurinic/apyrimidinic site (F-site), hypoxanthine, uracil, 5,6-dihydrouracil, the α-anomer of adenosine, or 1,N6-ethenoadenosine. Our examination of DNA cleavage activity and fluorescence time courses characterizing conformational changes of the dye-labeled DNA substrates during the interaction with EndoQ revealed that the enzyme induces multiple conformational changes of DNA in the course of binding. Moreover, the obtained data suggested that the formation of the enzyme–substrate complex can proceed through dissimilar kinetic pathways, resulting in different types of DNA conformational changes, which probably allow the enzyme to perform its biological function at an extreme temperature.