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541 results on '"Watanabe, Nobuhisa"'

15. Structures and mechanisms of actin ATP hydrolysis

Author

Kanematsu, Yusuke, primary, Narita, Akihiro, additional, Oda, Toshiro, additional, Koike, Ryotaro, additional, Ota, Motonori, additional, Takano, Yu, additional, Moritsugu, Kei, additional, Fujiwara, Ikuko, additional, Tanaka, Kotaro, additional, Komatsu, Hideyuki, additional, Nagae, Takayuki, additional, Watanabe, Nobuhisa, additional, Iwasa, Mitsusada, additional, Maéda, Yuichiro, additional, and Takeda, Shuichi, additional

Published
2022
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21. Structures and mechanisms of actin ATP hydrolysis

Author

Kanematsu, Yusuke, Narita, Akihiro, Oda, Toshiro, Koike, Ryotaro, Ota, Motonori, Takano, Yu, Moritsugu, Kei, Fujiwara, Ikuko, Tanaka, Kotaro, Komatsu, Hideyuki, Nagae, Takayuki, Watanabe, Nobuhisa, Iwasa, Mitsusada, Maéda, Yuichiro, Takeda, Shuichi, Kanematsu, Yusuke, Narita, Akihiro, Oda, Toshiro, Koike, Ryotaro, Ota, Motonori, Takano, Yu, Moritsugu, Kei, Fujiwara, Ikuko, Tanaka, Kotaro, Komatsu, Hideyuki, Nagae, Takayuki, Watanabe, Nobuhisa, Iwasa, Mitsusada, Maéda, Yuichiro, and Takeda, Shuichi

Abstract

The major cytoskeleton protein actin undergoes cyclic transitions between the monomeric G-form and the filamentous F-form, which drive organelle transport and cell motility. This mechanical work is driven by the ATPase activity at the catalytic site in the F-form. For deeper understanding of the actin cellular functions, the reaction mechanism must be elucidated. Here, we show that a single actin molecule is trapped in the F-form by fragmin domain-1 binding and present their crystal structures in the ATP analog-, ADP-Pi-, and ADP-bound forms, at 1.15-Å resolutions. The G-to-F conformational transition shifts the side chains of Gln137 and His161, which relocate four water molecules including W1 (attacking water) and W2 (helping water) to facilitate the hydrolysis. By applying quantum mechanics/molecular mechanics calculations to the structures, we have revealed a consistent and comprehensive reaction path of ATP hydrolysis by the F-form actin. The reaction path consists of four steps: 1) W1 and W2 rotations; 2) PG–O3B bond cleavage; 3) four concomitant events: W1–PO3− formation, OH− and proton cleavage, nucleophilic attack by the OH− against PG, and the abstracted proton transfer; and 4) proton relocation that stabilizes the ADP-Pi–bound F-form actin. The mechanism explains the slow rate of ATP hydrolysis by actin and the irreversibility of the hydrolysis reaction. While the catalytic strategy of actin ATP hydrolysis is essentially the same as those of motor proteins like myosin, the process after the hydrolysis is distinct and discussed in terms of Pi release, F-form destabilization, and global conformational changes.

Published
2022

25. Multi-Region and Multi-Component Thermal Fluid Analysis of Hydrothermal Oxidative Decomposition Reactor

Author

Kuramae, Hiroyuki, Sugimoto, Tokihiro, Matsumoro, Masahide, and Watanabe, Nobuhisa

Abstract

To elucidate the corrosion mechanism of a hydrothermal oxidation decomposition reactor for the treatment of polychlorinated biphenyls (PCBs), a coupled thermal fluid analysis of the heat transfer between two mixtures of fluids with different physical properties and the reactor body was executed using OpenFOAM. Based on the analysis results, we propose a method to evaluate the corrosion risk at the solid-liquid interface by focusing on three factors: (1) the corrosion temperature of reactor vessel, (2) the amount of fluid deposition that causes corrosion, and (3) the wall shear stress on the solid-liquid interface. Variation of corrosion risk with operating conditions of the reactor is discussed.

Published
2022
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42. Identification of multiple amyloidogenic sequences in laminin-1

Author

Kasai, Shingo, Urushibata, Shunsuke, Hozumi, Kentaro, Yokoyama, Fumiharu, Yamada, Yoshihiko, Nomizu, Motoyoshi, Ichikawa, Naoki, Kadoya, Yuichi, Nishi, Norio, and Watanabe, Nobuhisa

Subjects
Amyloidosis -- Research, Peptides -- Research, Amino acid sequence -- Research, Biological sciences, Chemistry
Abstract

Nearly 60 cell adhesive peptides derived from laminin-1 were screened for identification of additional amyloidogenic sequences. The results show that at least five laminin derived peptides can form amyloid-like fibrils, thus concluding that the laminin derived amyloidogenic peptides have the potential to form amyloid-like fibrils in vivo when laminin-1 is degraded.

Published
2007

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