Yasunori Inoue

Tokyo University of Science, Edo, Tōkyō, Japan

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Publications (24)75.6 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes the construction of a photogenerated electron transfer system based on photosystem I (PSI) and modified molecular wires. Gold electrode surfaces were functionalized with sodium 3-mercapto-1-propanesulfonate and the 2,2′-dimethyl-4,4′-bipyridine cation to form a self-assembled monolayer, which enabled the subsequent immobilization of PSI. A higher photocurrent was observed in the presence of sodium ascorbate as an electron donor under irradiation at 680 nm.
    Thin Solid Films 06/2012; 520(16):5123–5127. · 1.87 Impact Factor
  • Megumi Narukawa, Keiji Watanabe, Yasunori Inoue
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    ABSTRACT: Previously, we reported that chlorogenic acid (CGA) facilitated root hair formation at pH 4.0 in lettuce (Lactuca sativa L. cv. Grand Rapids). Light was essential for this process. In the present study, we determined relationships between CGA, light, and sugar during root hair formation in lettuce seedlings. The amount of CGA increased with white light in intact seedlings. Exogenously applied CGA restored root hair formation in dark-grown intact seedlings at pH 4.0. However, no root hair formation was induced in decapitated seedlings regardless of light exposure and CGA application. Application of sucrose or glucose induced both root hair formation and CGA synthesis in light-grown decapitated seedlings at pH 4.0. Blue light was the most effective for both root hair formation and CGA synthesis when supplied with sucrose to decapitated seedlings. Addition of sucrose and CGA together induced root hair formation at pH 4.0 in dark-grown decapitated seedlings. Results suggest that light induced CGA synthesis from sugar in the roots. Sugar was also required for root hair formation other than starting material of CGA synthesis. In addition, an unknown low pH-induced factor was essential for lettuce root hair formation.
    Journal of Plant Research 05/2010; 123(6):789-99. · 2.06 Impact Factor
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    ABSTRACT: Photosensing performance of a system composed of photosystem I (PSI), vitamin K(1) (VK(1))-like molecular wire, and gold nanoparticles (AuNPs) in an aqueous solution was increased considerably by the addition of double surfactants, hexylamine and dodecylbenzenesulfonate.
    Chemical Communications 04/2010; 46(15):2557-9. · 6.38 Impact Factor
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    ABSTRACT: PsbK is a small membrane protein of the PSII core complex and is highly conserved from cyanobacteria to plants. Here, we studied its role in the thermophilic cyanobacterium, Thermosynechococcus elongatus BP-1, by focusing on a psbK disruptant with hexahistidine-tagged CP47. The psbK disruptant showed photoautotrophic growth comparable with that of the wild type under a wide range of light conditions. The mutant PSII complex retained the oxygen-evolving activity with a unique modification of the acceptor Q(B) site. N-terminal sequencing revealed that Ycf12 and PsbZ proteins were lost in the PSII complex prepared from the mutant. Immunoblotting detected reduced accumulation of PsbZ in the mutant thylakoid. These results suggest that PsbK is required not only for association of PsbZ and Ycf12 with the isolated PSII complex but also for the stabilization of PsbZ in the thylakoid membrane.
    Plant and Cell Physiology 03/2010; 51(4):554-60. · 4.13 Impact Factor
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    ABSTRACT: A new bio-imaging sensor with photosystem I (PSI) of Thermosynechococcus elongatus and complementary metal-oxide-semiconductor (CMOS) circuits is demonstrated. Photons are converted into electrons by PSI, and electrons are detected as an electric signal by a CMOS integrated circuit. For a sensor circuit, a 4 × 4 sensor array with a CMOS source-drain follower is designed and fabricated by a standard CMOS process. An extended-gate electrode and an SU-8 passivation layer are formed on a CMOS chip by a post-CMOS process, and PSI is electrostatically fixed on the electrode. A 3× 4 image of the pattern of light illuminated on a chip is taken with the sensor array, where four cells are used as reference cells.
    Japanese Journal of Applied Physics 01/2010; 49(4). · 1.07 Impact Factor
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    ABSTRACT: Root hair formation is induced in lettuce seedlings when the seedlings are transferred from a liquid medium at pH 6.0 to one at pH 4.0. Auxin, ethylene, and light are also required for the induction of root hair formation. To investigate the mechanism by which ethylene production is regulated during root hair formation, we isolated three 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase genes (Ls-ACO1, 2, and 3) from lettuce, each of which exists as a single copy in the genome. Analysis of the deduced amino acid sequences of the three ACO proteins as well as a phylogenetic analysis revealed that Ls-ACO3 was the most divergent among the ACO family. Northern hybridization analyses revealed that the mRNA levels of Ls-ACO2, but not Ls-ACO1 and Ls-ACO3, increased in the primary root after the transfer to a pH 4.0 medium. Addition of ACC or indole-3-acetic acid (IAA) to the pH 6.0 medium induced root hair formation, and a concomitant accumulation of Ls-ACO2 mRNA was observed. In contrast, the mRNA levels of Ls-ACO1 and Ls-ACO3 were unaffected by either ACC or IAA treatment. Furthermore, white light irradiation of dark-grown seedlings following the transfer to pH 4.0 medium induced the accumulation of all three ACO mRNAs. However, accumulation of Ls-ACO2 mRNA was also observed in non-irradiated seedlings, suggesting that the expression of Ls-ACO2 was induced not by light but by low pH. These results suggest that among the differentially regulated ACO genes, Ls-ACO2 plays a key role in ethylene production during low-pH-induced root hair formation in lettuce. KeywordsACC oxidase-Ethylene-Gene expression- Lactuca sativa L.-Low pH-Root hair
    Plant Growth Regulation 01/2010; 62(2):137-149. · 1.67 Impact Factor
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    ABSTRACT: A new bio-photosensor where photons are converted to electrons by photosystem I (PSI) of Thermosynechococcus elongatus is described; in this bio-photosensor, the converted electronic charge is sensed by a complementary metal-oxide-semiconductor (CMOS) source-drain follower circuit fabricated by the 1.2 mum standard CMOS process. Thin Au/Ti films are deposited and patterned with a 4.255× 4.255 mum2 extended-gate electrode, and an SU-8 layer is formed, with the exception of the electrode, to reduce the light-induced drift of silicon nitride. As a result, only the Au electrode and the SU-8 layer come into contact with the electrolyte. The PSI is immobilized on the electrode, and the photoresponse due to the photovoltaic effect of PSI is measured as the output voltage of the CMOS source-drain follower. The action spectrum from the light source is consistent with the PSI absorption spectrum. In addition, the selectivity of the photoresponse between two adjacent sensor cells is confirmed, which is promising for ultrasensitive bioimage sensing.
    Japanese Journal of Applied Physics 01/2010; 49(1). · 1.07 Impact Factor
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    ABSTRACT: We have investigated a photosensor that consists of a field emission transistor (FET) utilizing the biocomponent of the photosystem I (PSI) protein complex for use in an imaging device. The PSI was immobilized on a gold electrode via the self-assembling monolayer (SAM) of 3-mercapto-1-propanesulfonic acid sodium salt to obtain a PSI-modified gold electrode. As for the PSI-modified gold electrode, the basic photoresponses originating from the excitation of PSI, including the photocurrent (106 nA) and the photoresponse of the open-circuit voltage (photo-Voc: 28.6 mV), were characterized. Then, the PSI-modified gold electrode was linked to the gate of the FET using a lead line, and the device was successfully driven by the photoelectric signals from the PSI like a voltage follower circuit. Further, we successfully demonstrated that the PSI-based FET acts as a photosensor in imaging devices.
    Langmuir 10/2009; 25(19):11969-74. · 4.38 Impact Factor
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    ABSTRACT: We present a bio-photoelectrode made of photosystem I complex (PSI) of cyanobacteria, Thermosynechococcus elongatus, and molecular wires. The newly designed and synthesized molecular wire similar to vitamin K1 (VK1) has a naphthoquinone moiety that can connect to PSI, and a terpyridine moiety for connection to a Co(II) ion. Surface immobilization of PSI and molecular wires was performed by a self-assembled monolayer (SAM) formation process at indium tin oxide (ITO) followed by stepwise coordination reactions. The PSI-immobilized ITO showed a photocurrent action spectrum, whose profile was consistent with that of PSI. We have demonstrated a new method for the immobilization of PSI on the electrode surface, useful in the construction of phovoltaic cells or photon-sensing devices.
    Journal of Nanoscience and Nanotechnology 04/2009; 9(3):1722-6. · 1.15 Impact Factor
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    ABSTRACT: Root hairs, which arise from root epidermal cells, are tubular structures that increase the efficiency of water absorption and nutrient uptake. A low pH (pH 4) medium induced root hair formation in lettuce (Lactuca sativa L.) seedlings, and the decapitation of shoots inhibited root hair formation. The addition of shoot extract to the medium restored root hair formation in the decapitated lettuce seedlings. These results suggest that factors essential to the formation of root hairs may be present in the shoot. We purified one factor from the shoot that facilitates root hair formation. This factor was identified as chlorogenic acid (CGA), a common polyphenol in higher plants. The presence of exogenous CGA in the medium induced root hair formation in decapitated lettuce seedlings at pH 4.0 and in intact lettuce seedlings at pH 6.0. The optimum concentration of CGA for root hair formation was identified as 10(-5) M. Decapitation of the shoots reduced the CGA content in the roots to approximately one-third that in intact plants. Application of the CGA biosynthesis inhibitor L-alpha-aminooxy-beta-phenylpropionic acid (AOPP, 10(-6) M) to intact seedlings grown at pH 4.0 reduced both the CGA content of the roots and the total amount of root hairs. The addition of exogenous CGA restored root hair formation in intact seedlings treated with AOPP. These results suggest that CGA is essential for root hair formation in lettuce seedlings.
    Plant and Cell Physiology 02/2009; 50(3):504-14. · 4.13 Impact Factor
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    ABSTRACT: Plug and play: Photoinduced electron transfer occurs from photoexcited P700 in photosystem I (PSI) to a gold surface (see picture). A novel molecular connector system is used, in which an artificial molecular wire, which is assembled on the gold surface, was plugged into PSI by reconstitution. Analysis of the photoelectron transfer kinetics proved both the output of electrons from PSI and the effectiveness of the molecular wire.
    Angewandte Chemie International Edition 02/2009; 48(9):1585-7. · 11.34 Impact Factor
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    ABSTRACT: PsbZ (Ycf9) is a membrane protein of PSII complexes and is highly conserved from cyanobacteria to plants. We deleted the psbZ gene in the thermophilic cyanobacterium, Thermosynechococcus elongatus. The mutant cells showed photoautotrophic growth indistinguishable from that of the wild type under low and standard light conditions, while they showed even better growth than the wild type under high light. The mutant accumulated less carotenoids and more phycobiliproteins than the wild type under high light, suggestive of tolerance to photoinhibition. The mutant cells evolved oxygen at a rate comparable with the wild type, while the PSII complex isolated from the mutant retained much lower activity than the wild type. N-terminal sequencing revealed that Ycf12 and PsbK proteins were almost lost in the PSII complex. These results indicate that PsbZ is involved in functional integrity of the PSII complex by stabilizing PsbK and Ycf12. We suggest that Ycf12 is an unidentified membrane-spanning polypeptide that is placed near PsbZ and PsbK in the crystal structure of PSII.
    Plant and Cell Physiology 01/2008; 48(12):1758-63. · 4.13 Impact Factor
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    ABSTRACT: Bio-components from living body are very attractive nano-materials, because they have already achieved ultra-high and ultimate performance as the result of many cycles of natural selection and mutation. We first succeeded in obtaining the electron from the electron relay system in the inside of PSI by use of molecular wire as a connector, which was designed for facile electron transfer, and also demonstrated FET-operation using the electrons from PSI via. the molecular wire. This study has confirmed the validity of the novel approach and strategy to utilize bio-components as the core parts in an artificial system, which can be applied to many kinds of bio-functions.
    Shinku 01/2008; 50(12):745-751.
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    ABSTRACT: It is well known that photosystem II (PSII) can produce electrons, oxygen, and protons simultaneously via a water-splitting photoreaction. These photochemical properties are expected to exhibit photoconductive function for PSII. In the present study, we have first observed a stable photocurrent due to the photoexcitation of PSII and the subsequent water-splitting reaction, by successfully immobilizing PSII on the self-assembled monolayer (SAM) of a nickel-nitrilotriacetic acid complex (Ni-NTA) prepared on a gold surface via a polyhistidine tag (Histag) as a linker molecule. We have further succeeded in the fabrication of PSII-gold nanoparticle multistructures on the surface of gold electrode, and significant enhancement of photocurrents was achieved due to increased number of immobilized PSII.
    Thin Solid Films 01/2008; 516(9):2553-2557. · 1.87 Impact Factor
  • Source
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    ABSTRACT: We report on the first successful output of electrons directly from photosystem I (PSI) of thermophilic cyanobacteria to the gate of a field-effect transistor (FET) by bypassing electron flow via a newly designed molecular wire, i.e., artificial vitamin K(1), and a gold nanoparticle; in short, this newly manufactured photosensor employs a bio-functional unit as the core of the device. Photo-electrons generated by the irradiation of molecular complexes composed of reconstituted PSI on the gate were found to control the FET. This PSI-bio-photosensor can be used to interpret gradation in images. This PSI-FET system is moreover sufficiently stable for use exceeding a period of 1 year.
    Biochimica et Biophysica Acta 07/2007; 1767(6):653-9. · 4.66 Impact Factor
  • Masae Konno, Machiko Ooishi, Yasunori Inoue
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    ABSTRACT: We investigated whether low-pH-induced manganese (Mn) deficiency causes low-pH-induced root hair formation in lettuce seedlings. Both the number and length of root hairs increased in 0 microM Mn (Mn-free) at pH 6 and decreased in 3 mM Mn (excess Mn) at pH 4 compared with the values in 10 microM Mn (normal Mn). These results indicate an inhibitory effect of Mn on both root hair initiation and elongation. The time dependency of root hair induction caused by Mn deficiency corresponded to that caused by low pH. Within 1 h after the pH of the culture medium was reduced from pH 6 to pH 4, the Mn uptake by roots decreased to 43% of that at pH 6. These results suggest that low-pH-induced Mn deficiency promotes root hair formation. At low pH, the rate of Mn uptake was reduced in areas >2 mm from the root tip. Roots with low-pH-induced root hairs still showed low Mn uptake during 3 h of incubation at pH 6. Therefore, the additional root hairs induced by low pH did not compensate for the low-pH-induced decrease in Mn uptake.
    Journal of Plant Research 09/2006; 119(5):439-47. · 2.06 Impact Factor
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    ABSTRACT: We have first prepared a novel bio-nanohybrid electrode consisting of a photosynthetic protein complex, photosystem I (PSI), and gold nanoparticles, and have measured their photocurrent generation properties. The hybrid electrode was fabricated by three steps: sedimentation of gold nanoparticles on a planar gold substrate, followed by modification with 3-mercapto-1-propanesulfonic acid by gold–sulfur self-assembling, and finally modification with PSI by electrostatic adsorption. Even though PSI is one of the proteins and is much larger than usual organic dyes for photocurrent generation, we have. succeeded in constructing PSI–gold nanoparticle hybrid electrodes, and in obtaining substantially greater photocurrent responses from PSI as compared with the corresponding planar electrode system.
    Thin Solid Films 01/2006; 499:153-156. · 1.87 Impact Factor
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    ABSTRACT: To elucidate the domains on the extrinsic 23 kDa protein involved in electrostatic interaction with the extrinsic 33 kDa protein in spinach photosystem II, we modified amino or carboxyl groups of the 23 kDa protein to uncharged methyl ester groups with N-succinimidyl propionate or glycine methyl ester in the presence of a water-soluble carbodiimide, respectively. The N-succinimidyl propionate-modified 23 kDa protein did not bind to the 33 kDa protein associated with PSII membranes, whereas the glycine methyl ester-modified 23 kDa protein completely bound. This indicates that positive charges on the 23 kDa protein are important for electrostatic interaction with the 33 kDa protein associated with the PSII membranes. Mapping of the N-succinimidyl propionate-modified sites of the 23 kDa protein was performed using Staphylococcus V8 protease digestion of the modified protein followed by determination of the mass of the resultant peptide fragments with MALDI-TOF MS. The results showed that six domains (Lys11-Lys14, Lys27-Lys38, Lys40, Lys90-Lys96, Lys143-Lys152, Lys166-Lys174) were modified with N-succinimidyl propionate. In these domains, Lys11, Lys13, Lys33, Lys38, Lys143, Lys166, Lys170 and Lys174 were wholly conserved in the 23 kDa protein from 12 species of higher plants. These positively charged lysyl residues on the 23 kDa protein may be involved in electrostatic interactions with the negatively charged carboxyl groups on the 33 kDa protein, the latter has been suggested to be important for the 23 kDa binding [Bricker, T.M. & Frankel, L.K. (2003) Biochemistry42, 2056-2061].
    European Journal of Biochemistry 04/2004; 271(5):962-71. · 3.58 Impact Factor
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    ABSTRACT: Transverse cortical microtubule (CMT) arrays in lettuce root epidermal cells randomize soon after a shift from pH 6.0 to pH 4.0, and this randomization is essential for root hair initiation. We investigated the hormonal regulation of CMT randomization. At pH 4.0, 1 micro M of the auxin competitive inhibitor 2-(p-chlorophenoxy)-2-methylpropionic acid (PCIB), 0.1 micro M of the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) or 0.1 micro M of the ethylene action inhibitor Ag(+) suppressed CMT randomization and root hair initiation. At pH 6.0, addition of 0.1 micro M indole-3-acetic acid (IAA) or 1 micro M of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) induced CMT randomization and root hair initiation. Culturing with 0.1 micro M IAA plus 0.1 micro M AVG, or 1 micro M ACC plus 1 micro M PCIB also induced these phenomena. ACC (1 micro M) plus 100 micro M PCIB inhibited CMT randomization and root hair initiation, but 1 micro M AVG with 0.1 micro M Ag(+) and 0.1 micro M IAA induced them. These results suggest that auxin is essential for CMT randomization. As a higher concentration of PCIB was required to suppress CMT randomization when ACC was added, the greater amount of ethylene produced at pH 4.0 may promote the induction by auxin of CMT randomization in hair-forming cells.
    Plant and Cell Physiology 10/2003; 44(9):932-40. · 4.13 Impact Factor
  • Masae Konno, Machiko Ooishi, Yasunori Inoue
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    ABSTRACT: Root hair formation is induced by low pH in lettuce ( Lactuca sativa L. cv. Grand Rapids) seedlings cultured in mineral medium. The role of mineral concentrations in this phenomenon was investigated, especially for manganese. When lettuce seedlings were cultured in media that were deficient in calcium (Ca), manganese (Mn), boron (B) or molybdenum (Mo), morphological changes were induced in roots. Deficiency of other nutrients had little effect on root hair formation. Ca or B deficiency inhibited the growth of the main root and the formation of root hairs, regardless of pH. Mn or Mo deficiency increased root hair formation at pH 6 and suppressed main root growth slightly. In contrast, increasing the Mn concentration suppressed low-pH-induced root hair formation. The Mn content of roots grown at pH 4 was only about 15% of that at pH 6. In contrast, the Mo content of roots grown at low pH was about six times that of roots grown at neutral pH. These results suggest that root hair formation induced by low pH is at least partly mediated by decreased Mn uptake in root cells.
    Journal of Plant Research 09/2003; 116(4):301-7. · 2.06 Impact Factor