Journal Article

Unique Fluorescence Properties of a Cyanobacterium <i>Gloeobacter violaceus</i> PCC 7421: Reasons for Absence of the Long-Wavelength PSI Chl <i>a</i> Fluorescence at –196°C

Mamoru Mimuro, Takahiro Ookubo, Daisuke Takahashi, Takahiro Sakawa, Seiji Akimoto, Iwao Yamazaki and Hideaki Miyashita

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 6, pages 587-594
Published in print June 2002 | ISSN: 0032-0781
Published online June 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf070
Unique Fluorescence Properties of a Cyanobacterium Gloeobacter violaceus PCC 7421: Reasons for Absence of the Long-Wavelength PSI Chl a Fluorescence at –196°C

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We investigated the reason for the absence of the long-wavelength PSI Chl a fluorescence at –196°C in the cyanobacterium Gloeobacter violaceus using two methods: p-nitrothiophenol (p-NTP) treatment and time-resolved fluorescence spectra. The p-NTP treatment showed that PSII Chl a fluorescence was specifically affected in a manner similar to that for Synechocystis sp. PCC 6803 and spinach chloroplasts, although there were no components modified by the p-NTP treatment, indicating an absence of the long-wavelength PSI Chl a fluorescence. The time-resolved fluorescence spectra with a time resolution of 1.3 ps and spectral resolution of 1.0 nm gave no indication of the presence of the long-wavelength PSI fluorescence in the wavelength region between 700 nm and 760 nm, indicating that a very fast energy transfer among Chl a molecules could not account for the absence of the long-wavelength PSI fluorescence. From these data, it seems that the absence of the long-wavelength PSI fluorescence is due to a lack of the formation of a component responsible for the fluorescence at –196°C, which may originate from a difference in the amino acid sequence. We discuss the significance of this phenomenon and interpret our findings in terms of the evolution of cyanobacteria.

Keywords: Keywords: Antenna — Energy transfer — Evolution — Fluorescence — Gloeobacter violaceus — Photosynthesis.; Abbreviations: APC, allophycocyanin; p-NTP, p-nitrothiophenol; P700, the primary electron donor in PSI; PC, phycocyanin; PE, phycoerythrin; PS, photosystem, TAC, time-to-amplitude converter; TRFS, time-resolved fluorescence spectra.

Journal Article.  5896 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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