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1 0 0 0 OA Spectroscopic approach for exploring structure and function of photoreceptor proteins

著者
Masashi Unno Yuu Hirose Masaki Mishima Takashi Kikukawa Tomotsumi Fujisawa Tatsuya Iwata Jun Tamogami
出版者
The Biophysical Society of Japan
雑誌
Biophysics and Physicobiology (ISSN:21894779)
巻号頁・発行日
vol.18, pp.127-130, 2021 (Released:2021-06-18)
参考文献数
26
被引用文献数
2

1 0 0 0 OA Structural role of two histidines in the (6-4) photolyase reaction

著者
Daichi Yamada Tatsuya Iwata Junpei Yamamoto Kenichi Hitomi Takeshi Todo Shigenori Iwai Elizabeth D. Getzoff Hideki Kandori
出版者
一般社団法人 日本生物物理学会
雑誌
Biophysics and Physicobiology (ISSN:21894779)
巻号頁・発行日
vol.12, pp.139-144, 2015 (Released:2015-12-22)
参考文献数
34
被引用文献数
1 8
Photolyases (PHRs) are DNA repair enzymes that revert UV-induced photoproducts, either cyclobutane pyrimidine dimers (CPD) or (6-4) photoproducts (PPs), into normal bases to maintain genetic integrity. (6-4) PHR must catalyze not only covalent bond cleavage, but also hydroxyl or amino group transfer, yielding a more complex mechanism than that postulated for CPD PHR. Previous mutation analysis revealed the importance of two histidines in the active center, H354 and H358 for Xenopus (6-4) PHR, whose mutations significantly lowered the enzymatic activity. Based upon highly sensitive FTIR analysis of the repair function, here we report that both H354A and H358A mutants of Xenopus (6-4) PHR still maintain their repair activity, although the efficiency is much lower than that of the wild type. Similar difference FTIR spectra between the wild type and mutant proteins suggest a common mechanism of repair in which (6-4) PP binds to the active center of each mutant, and is released after repair, as occurs in the wild type. Similar FTIR spectra also suggest that a decrease in volume by the H-to-A mutation is possibly compensated by the addition of water molecule(s). Such a modified environment is sufficient for the repair function that is probably controlled by proton-coupled electron transfer between the enzyme and substrate. On the other hand, two histidines must work in a concerted manner in the active center of the wild-type enzyme, which significantly raises the repair efficiency.