Multiple pathways of excitation energy flow in the photosynthetic pigment system of a cryptophyte, cryptomonas sp. (CR-1)

Mamoru Mimuro, Naoto Tamai, Akio Murakami, Masakatsu Watanabe, Mayumi Erata, Makoto M. Watanabe, Mitsue Tokutomi, Iwao Yamazaki

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Energy transfer pathways in a cryptophyte, Cryptomonas sp. (CR-1 strain) were investigated mainly by the steady state fluorescence spectroscopy and the time-resolved spectrum. Cryptomonas sp. (CR-1) contains chlorophyll (Chl) a, Chl c2, carotenoids and cryptomonad phycoerythrin (Cr-PE565), the last of which is known to be located in the lumenal side of the thylakoid membranes. The spectral heterogeneity of pigments was resolved by fluorescence spectra; there were at least five emission bands of Chl a at -196°C. Chlorophyll c2 and carotenoids transferred independently to the common Chl a form (Chl a663), and Cr-PE565, to the different form (Chl a682). Chlorophyll c2 was not an intermediary component of energy transfer from carotenoid to Chl a; this is a common phenomenon to green algae and brown algae. The Chl a663 and Chl a682 are postulated to be located in the light-harvesting chlorophyll protein (LHC) II; thus, the energy is accumulated on Chl a682 in LHC II. The energy transfer step in Cr-PE565 was short, which was shown by a small, time-dependent red-shift of the emission. In the photosystem (PS) II core, two fluorescence components were resolved at 688 and 696 nm. The former was the trap at cryogenic temperatures. A large red-shift induced by the low temperature was explained by an equilibrium between Chl a682 in LHC II and Chl a688 in PS II core. The presence of Chl a682 emission at physiological temperature is a unique feature of this alga. This was also reported in dinophyceae, which contain peridinin-Chl a-protein in the lumenal side of the thylakoid membrane. Thus, this modification might be common in systems where the antenna complexes bind to the LHC II on the lumenal side. Based on the spectral data, we proposed a model for the molecular organization of PS II and the energy transfer pathways in cryptophyceae.

Original languageEnglish
Pages (from-to)155-164
Number of pages10
JournalPhycological Research
Volume46
Issue number3
DOIs
Publication statusPublished - 1998 Sep
Externally publishedYes

Keywords

  • Carotenoid
  • Cryptomonas sp.
  • Energy transfer
  • Photosynthesis
  • Phycobilin
  • Ultra-fast spectroscopy

ASJC Scopus subject areas

  • Aquatic Science
  • Agricultural and Biological Sciences (miscellaneous)
  • Plant Science

Fingerprint Dive into the research topics of 'Multiple pathways of excitation energy flow in the photosynthetic pigment system of a cryptophyte, cryptomonas sp. (CR-1)'. Together they form a unique fingerprint.

Cite this