2Institute of Basic Biological Problems, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
3Lomonosov Moscow State University, Faculty of Biology, 119991 Moscow, Russia
4Tokyo University of Science, Department of Biology, Faculty of Science, Kagurazaka 1-3, Shinjuku-ku, 162-8601 Tokyo, Japan
5PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, 332-0012 Saitama, Japan
6Okayama University, Faculty of Science, Photosynthesis Research Center, Graduate School of Natural Science and Technology, 700-8530 Okayama, Japan
* To whom correspondence should be addressed.
Received June 3, 2015; Revision received August 28, 2015
The finding of unique Chl d- and Chl f-containing cyanobacteria in the last decade was a discovery in the area of biology of oxygenic photosynthetic organisms. Chl b, Chl c, and Chl f are considered to be accessory pigments found in antennae systems of photosynthetic organisms. They absorb energy and transfer it to the photosynthetic reaction center (RC), but do not participate in electron transport by the photosynthetic electron transport chain. However, Chl d as well as Chl a can operate not only in the light-harvesting complex, but also in the photosynthetic RC. The long-wavelength (Qy) Chl d and Chl f absorption band is shifted to longer wavelength (to 750 nm) compared to Chl a, which suggests the possibility for oxygenic photosynthesis in this spectral range. Such expansion of the photosynthetically active light range is important for the survival of cyanobacteria when the intensity of light not exceeding 700 nm is attenuated due to absorption by Chl a and other pigments. At the same time, energy storage efficiency in photosystem 2 for cyanobacteria containing Chl d and Chl f is not lower than that of cyanobacteria containing Chl a. Despite great interest in these unique chlorophylls, many questions related to functioning of such pigments in primary photosynthetic processes are still not elucidated. This review describes the latest advances in the field of Chl d and Chl f research and their role in primary photosynthetic processes of cyanobacteria.
KEY WORDS: chlorophyll d, chlorophyll f, photosystem 1, photosystem 2, photosynthesis, energetics of photosystems, spectral properties, cyanobacteria