Insight into the functions of the flexible N-terminal domain and the [4Fe-4S] cluster of human NTH1

Human endonuclease III or hNTH1, is an FeS containing enzyme, which recognizes and removes oxidized pyrimidines from DNA. Unlike its bacterial counterparts, hNTH1 possesses an additional N-terminal extension of 100 amino acids that has been proposed to function in nuclear and mitochondrial targeting and in regulation of its catalytic activity through protein-protein interactions. The crystal structure of a N-terminally truncated construct of hNTH1 was recently determined confirming the intrinsic flexibility of the N-terminal extension and revealing a new ‘open’ conformation for the catalytic region.

In this work, we have performed a comparative biophysical study of full-length and an N-terminally truncated hNTH1 containing only the catalytic domain, similar to bacterial EndoIII. Using a combination of vibrational spectroscopy, spectroelectrochemistry and small-angle X-ray scattering (SAXS) experiments, we reveal distinct properties of the two enzyme forms, and indicate that the N-terminal domain is important for DNA binding at the onset of damage recognition.

Moe E, Silveira CM, Zuccarello L, Rollo F, Stelter M, De Bonis S, Kulka-Peschke C, Katz S, Hildebrandt P, Zebger I, Timmins J & Todorovic S. Human Endonuclease III/NTH1 : Focusing on the [4Fe-4S] cluster and the N-terminal domain. Chem Comm (2022) 58 p. 12568-12571. DOI : 10.1039/D2CC03643F.