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Updated: Jun 4, 2026

Single-Molecule Dwell-Time Analysis of Restriction Endonuclease-Mediated DNA Cleavage
Published on: February 7, 2021
An additional C-terminal loop in endonuclease IV, an apurinic/apyrimidinic endonuclease, controls binding affinity to
Ryuichi Asano1, Hirohito Ishikawa, Shuhei Nakane
1Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.
Abstract:
Endonuclease IV (EndoIV) is an endonuclease that acts at apurinic/apyrimidinic (AP) sites and is classified as either long-type or short-type. The crystal structures of representative types of EndoIV from Geobacillus kaustophilus and Thermus thermophilus HB8 were determined using X-ray crystallography. G. kaustophilus EndoIV (the long type) had a higher affinity for double-stranded DNA containing an AP-site analogue than T. thermophilus EndoIV (the short type). Structural analysis of the two different EndoIVs suggested that a C-terminal DNA-recognition loop that is only present in the long type contributes to its high affinity for AP sites. A mutation analysis showed that Lys267 in the C-terminal DNA-recognition loop plays an important role in DNA binding.
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