著者

Yu Nakajima Takashi Tsukamoto Yohei Kumagai Yoshitoshi Ogura Tetsuya Hayashi Jaeho Song Takashi Kikukawa Makoto Demura Kazuhiro Kogure Yuki Sudo Susumu Yoshizawa

出版者

Japanese Society of Microbial Ecology · The Japanese Society of Soil Microbiology

雑誌

Microbes and Environments (ISSN:13426311)

巻号頁・発行日

vol.33, no.1, pp.89-97, 2018 (Released:2018-03-29)

参考文献数

43

被引用文献数

17

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Light-driven ion-pumping rhodopsins are widely distributed among bacteria, archaea, and eukaryotes in the euphotic zone of the aquatic environment. H+-pumping rhodopsin (proteorhodopsin: PR), Na+-pumping rhodopsin (NaR), and Cl−-pumping rhodopsin (ClR) have been found in marine bacteria, which suggests that these genes evolved independently in the ocean. Putative microbial rhodopsin genes were identified in the genome sequences of marine Cytophagia. In the present study, one of these genes was heterologously expressed in Escherichia coli cells and the rhodopsin protein named Rubricoccus marinus halorhodopsin (RmHR) was identified as a light-driven inward Cl− pump. Spectroscopic assays showed that the estimated dissociation constant (Kd,int.) of this rhodopsin was similar to that of haloarchaeal halorhodopsin (HR), while the Cl−-transporting photoreaction mechanism of this rhodopsin was similar to that of HR, but different to that of the already-known marine bacterial ClR. This amino acid sequence similarity also suggested that this rhodopsin is similar to haloarchaeal HR and cyanobacterial HRs (e.g., SyHR and MrHR). Additionally, a phylogenetic analysis revealed that retinal biosynthesis pathway genes (blh and crtY) belong to a phylogenetic lineage of haloarchaea, indicating that these marine Cytophagia acquired rhodopsin-related genes from haloarchaea by lateral gene transfer. Based on these results, we concluded that inward Cl−-pumping rhodopsin is present in genera of the class Cytophagia and may have the same evolutionary origins as haloarchaeal HR.

著者

Yu Nakajima Keiichi Kojima Yuichiro Kashiyama Satoko Doi Ryosuke Nakai Yuki Sudo Kazuhiro Kogure Susumu Yoshizawa

出版者

Japanese Society of Microbial Ecology / Japanese Society of Soil Microbiology / Taiwan Society of Microbial Ecology / Japanese Society of Plant Microbe Interactions / Japanese Society for Extremophiles

雑誌

Microbes and Environments (ISSN:13426311)

巻号頁・発行日

vol.35, no.4, pp.ME20085, 2020 (Released:2020-12-05)

参考文献数

36

被引用文献数

15

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Microbial rhodopsins, comprising a protein moiety (rhodopsin apoprotein) bound to the light-absorbing chromophore retinal, function as ion pumps, ion channels, or light sensors. However, recent genomic and metagenomic surveys showed that some rhodopsin-possessing prokaryotes lack the known genes for retinal biosynthesis. Since rhodopsin apoproteins cannot absorb light energy, rhodopsins produced by prokaryotic strains lacking genes for retinal biosynthesis are hypothesized to be non-functional in cells. In the present study, we investigated whether Aurantimicrobium minutum KNCT, which is widely distributed in terrestrial environments and lacks any previously identified retinal biosynthesis genes, possesses functional rhodopsin. We initially measured ion transport activity in cultured cells. A light-induced pH change in a cell suspension of rhodopsin-possessing bacteria was detected in the absence of exogenous retinal. Furthermore, spectroscopic analyses of the cell lysate and HPLC-MS/MS analyses revealed that this strain contained an endogenous retinal. These results confirmed that A. minutum KNCT possesses functional rhodopsin and, hence, produces retinal via an unknown biosynthetic pathway. These results suggest that rhodopsin-possessing prokaryotes lacking known retinal biosynthesis genes also have functional rhodopsins.

著者

Yu Nakajima Takashi Tsukamoto Yohei Kumagai Yoshitoshi Ogura Tetsuya Hayashi Jaeho Song Takashi Kikukawa Makoto Demura Kazuhiro Kogure Yuki Sudo Susumu Yoshizawa

出版者

Japanese Society of Microbial Ecology · The Japanese Society of Soil Microbiology

雑誌

Microbes and Environments (ISSN:13426311)

巻号頁・発行日

pp.ME17197, (Released:2018-03-16)

被引用文献数

17

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Light-driven ion-pumping rhodopsins are widely distributed among bacteria, archaea, and eukaryotes in the euphotic zone of the aquatic environment. H+-pumping rhodopsin (proteorhodopsin: PR), Na+-pumping rhodopsin (NaR), and Cl–-pumping rhodopsin (ClR) have been found in marine bacteria, which suggests that these genes evolved independently in the ocean. Putative microbial rhodopsin genes were identified in the genome sequences of marine Cytophagia. In the present study, one of these genes was heterologously expressed in Escherichia coli cells and the rhodopsin protein named Rubricoccus marinus halorhodopsin (RmHR) was identified as a light-driven inward Cl– pump. Spectroscopic assays showed that the estimated dissociation constant (Kd,int.) of this rhodopsin was similar to that of haloarchaeal halorhodopsin (HR), while the Cl–-transporting photoreaction mechanism of this rhodopsin was similar to that of HR, but different to that of the already-known marine bacterial ClR. This amino acid sequence similarity also suggested that this rhodopsin is similar to haloarchaeal HR and cyanobacterial HRs (e.g., SyHR and MrHR). Additionally, a phylogenetic analysis revealed that retinal biosynthesis pathway genes (blh and crtY) belong to a phylogenetic lineage of haloarchaea, indicating that these marine Cytophagia acquired rhodopsin-related genes from haloarchaea by lateral gene transfer. Based on these results, we concluded that inward Cl–-pumping rhodopsin is present in genera of the class Cytophagia and may have the same evolutionary origins as haloarchaeal HR.

著者

Takahiro SASAKI Hiroyuki OKAMOTO Yu NAKAJIMA Ryo NAKAMURA Toru YAMAMOTO

出版者

International Symposium on Space Technology and Science

雑誌

Journal of Evolving Space Activities (ISSN:27581802)

巻号頁・発行日

vol.1, pp.52, 2023 (Released:2023-06-30)

参考文献数

17

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Considerable research is being directed toward active debris removal (ADR) in space, especially by small, cost-effective satellites. In the descent phase, thrust vector control (TVC) is often utilized to maintain the satellite’s trajectory and thrust vector by gimbaling the thrust vector. A common challenge in performing TVC is that its effectiveness depends on the mass, moment of inertia and location of the thrusting point with respect to the center of mass. Since these properties change with fuel consumed during a mission, a designer needs to consider such parameters as they strongly affect the resulting dynamics. This paper introduces spacecraft dynamics with a gimbaled thruster and proposes an adaptive controller for TVC with model uncertainties. Through numerical examples, the effectiveness of the proposed controller is demonstrated for improved control performance.

著者

Takahiro SASAKI Yu NAKAJIMA Toru YAMAMOTO

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.64, no.3, pp.136-146, 2021 (Released:2021-05-04)

参考文献数

25

被引用文献数

1

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As the amount of debris in orbit increases, so does the risk of collisions and their seriousness. All nations involved with space operations acknowledge this growing threat. One solution receiving increased attention is active debris removal. The first step in a debris removal mission would be to approach the debris. In this phase, it is important to ensure passive abort safety and to guarantee the robustness against collisions in the case of off-nominal thruster burns, that may be caused by spacecraft anomalies such as navigation sensor or actuator failures. This paper compares two types of passive abort safe trajectories –the V-bar hopping and spiral approaches– considering the ΔV budget, the duration of operations, and variation in the line-of-sight vector to the target. This paper also proposes design strategies for determining the parameters in the two candidate trajectories, considering passive abort safety. The robustness of the trajectories against collisions due to off-nominal thruster burns is also demonstrated through Monte Carlo simulations. The paper investigates which trajectories are suitable for an active debris removal mission to a non-cooperative target.