Harvesting Far-Red Light by Chlorophyll f in Photosystems I and II of Unicellular Cyanobacterium strain KC1

Plant Cell Physiol. 2015 Oct;56(10):2024-34. doi: 10.1093/pcp/pcv122. Epub 2015 Aug 28.

Abstract

Cells of a unicellular cyanobacterium strain KC1, which were collected from Japanese fresh water Lake Biwa, formed chlorophyll (Chl) f at 6.7%, Chl a' at 2.0% and pheophytin a at 0.96% with respect to Chl a after growth under 740 nm light. The far-red-acclimated cells (Fr cells) formed extra absorption bands of Chl f at 715 nm in addition to the major Chl a band. Fluorescence lifetimes were measured. The 405-nm laser flash, which excites mainly Chl a in photosystem I (PSI), induced a fast energy transfer to multiple fluorescence bands at 720-760 and 805 nm of Chl f at 77 K in Fr cells with almost no PSI-red-Chl a band. The 630-nm laser flash, which mainly excited photosystem II (PSII) through phycocyanin, revealed fast energy transfer to another set of Chl f bands at 720-770 and 810 nm as well as to the 694-nm Chl a fluorescence band. The 694-nm band did not transfer excitation energy to Chl f. Therefore, Chl a in PSI, and phycocyanin in PSII of Fr cells transferred excitation energy to different sets of Chl f molecules. Multiple Chl f forms, thus, seem to work as the far-red antenna both in PSI and PSII. A variety of cyanobacterial species, phylogenically distant from each other, seems to use a Chl f antenna in far-red environments, such as under dense biomats, in colonies, or under far-red LED light.

Keywords: Chlorophyll f; Cyanobacteria; Far-red light; Light harvesting; PSI; PSII.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chlorophyll / analogs & derivatives*
  • Chlorophyll / metabolism
  • Cyanobacteria / metabolism*
  • Photosystem I Protein Complex / metabolism*
  • Photosystem II Protein Complex / metabolism*

Substances

  • Photosystem I Protein Complex
  • Photosystem II Protein Complex
  • chlorophyll f
  • Chlorophyll