32 research outputs found
Structures and mechanisms of actin ATP hydrolysis
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
Milnacipran treatment and potential biomarkers in depressed patients following an initial SSRI treatment failure: a prospective, open-label, 24-week study
Automatic Evacuation Guiding Scheme Based on Implicit Interactions Between Evacuees and Their Mobile Nodes
ヒナンシャ モバイル タンマツカン ノ アンモクテキ ナ レンケイ ニ モトズク ジドウテキ ナ ヒナン ユウドウ ホウシキ
修士(Master)工学(Engineering)奈良先端科学技術大学院大学修第6629
On Information Sharing Scheme for Automatic Evacuation Guiding System Using Evacuees’ Mobile Nodes
Automatic Evacuation Guiding Scheme Using Trajectories of Mobile Nodes
MobiWis 2015 : The 12th International Conference on Mobile Web and Intelligent Information Systems , Aug 24-26, 2015 , Rome, ItalyWhen large-scale disasters occur, evacuees have to evacuate to safe places quickly. In this paper, we propose an automatic evacuation guiding scheme using mobile nodes of evacuees. Each node tries to navigate its evacuee by presenting an evacuation route. It can also trace the actual evacuation route of the evacuee as the trajectory by measuring his/her positions periodically. The proposed scheme automatically estimates blocked road segments from the difference between the presented evacuation route and the actual evacuation route, and then recalculates the alternative evacuation route. In addition, evacuees also share such information among them through direct wireless communication with other mobile nodes and that with a server via remaining communication infrastructures. Through simulation experiments, we show that 1) the effectiveness of the proposed scheme becomes high with the increase of degree of damage and 2) the effect of information sharing through communication infrastructures is higher than that through direct wireless communication
Automatic evacuation guiding scheme based on implicit interactions between evacuees and their mobile nodes
When large-scale disasters occur, evacuees have to evacuate to safe places quickly. They, however, may not be able to afford to obtain sufficient information for their evacuations under such emergent situations. In this paper, we propose an automatic evacuation guiding scheme using evacuees’ mobile nodes, e.g., smart phones. The key idea to achieve automatic evacuation guiding is implicit interactions between evacuees and their mobile nodes. Each mobile node tries to navigate its evacuee by presenting an evacuation route. At the same time, it can also trace the actual evacuation route of the evacuee as the trajectory by measuring his/her positions periodically. The proposed scheme automatically estimates blocked road segments from the difference between the presented evacuation route and the actual evacuation route, and then recalculates the alternative evacuation route. In addition, evacuees also share such information among them through direct wireless communication with other mobile nodes and that with a server via remaining communication infrastructures. Through simulation experiments, we show that 1) the proposed scheme works well when the degree of damage is high and/or road segments are continuously blocked, 2) the average evacuation time can be improved even in small penetration ratio of the proposed system, and 3) the direct wireless communication can support many evacuations at almost the same level as the communication infrastructure when the number of evacuees becomes large