| Project/Area Number |
08836003
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
光生物学
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| Research Institution | Japan Advanced Institute of Science and Technology |
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Principal Investigator |
TAKAHASHI Tetsuo JAIST,School of Materials Sci., Associate Professor, 材料科学研究科, 助教授 (90133769)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Masakatsu National Institure for Basic Biology, Associate Professor, 基礎生物学研究所, 助教授 (40124226)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1997: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1996: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | phototexis / photophobic response / Euqlena / Chlamydomonas / archaeal rhodopsin / phoborhodopsin / PYP / retinal binding site / Halobacterium / Natronebacterium pharaonis / Ectothiorhodospira halophila / Chlamydomonas reinhardtii / Euglena / phototaxis / photophobic response / action spectrum / センサリ-ロドプシン / 高度好塩菌 / 光合成細菌 / イエロープロティン / オプシンシフト / トランスデューサー / メチル基受容タンパク |
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| Research Abstract |
During the period, the following new results were established as to various blue/blue-green photoreceptor-containing photomovement systems of microorganisms.
(1)The regulation system of the step-down and the step-up photophobic responses in the flagellate alga Euglena was for the first time revealed to be controlled by exogenous ammonium ion. Ammonium ion specifically increases the fraction of the step-down photophobically cells, whereas L-methionine-DL-sulfoximine, an inhibitor of ammonium assimilation, specifically increases the fraction of step-up photophobically responding cells in a cell suspension. This allowed us to measure independently the true action spectra for both step-up and step-down responses. The results suggested that the two responses are mediated by flavin-containing photoreceptors, having slightly different spectroscopic characters.
(2)Despite the reported fact that the receptors for photomovement responses of unicellular green alga Chlamydomonas has little homology
… More
to archaebacterial rhodopsins, our analog-reconstitution study has revealed a highly similar stereochemical architecture along the retinal binding site between the chlamydomons photoreceptor and halobacterial phoborhodopsin. Though this may suggest a possibility for unidentified photomovement receptor in Chlamydomonas having high homology to phoborhodopsin, we tentatively ascribed the result to a possible convergence in the evolution of blue-green sensitive photoreceptors, This is in accord with several lines of evidence that a wide variety of photoreceptor species mediates photomovement responses of various microorganisms to blue/blue-green light.
(3)PYP is one of the unique photoreceptors in eubacteria. We measured step-up photophobic response of Ectothiorhodospira halophila, containing PYP, and found that the action spectrum coincided with the absorption spectrum of PYP.
(4)A putative transducer-like protein mediating photophobic response of Ectothiorhodospira halophila has been cloned.
(5)A new member of phoborhodopsin was cloned from a halobacterial species from Australian salt lake.
(6)Phoborhodopsin from Natronobacteriurm pharaonis has been expressed in E.coil, and the recombinant protein is satisfactory purified by histidine tagging. Less
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