Red-shifted chlorophyll a bands allow uphill energy transfer to photosystem II reaction centers in an aerial green alga, Prasiola crispa, harvested in Antarctica

• Published in: Biochimica et biophysica acta. Bioenergetics Vol. 1861; no. 2; p. 148139
• Main Authors: Kosugi, Makiko, Ozawa, Shin-Ichiro, Takahashi, Yuichiro, Kamei, Yasuhiro, Itoh, Shigeru, Kudoh, Sakae, Kashino, Yasuhiro, Koike, Hiroyuki
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2020
• Subjects: Antarctic Regions; Antarctica; Chlorophyll A - metabolism; Chlorophyta - metabolism; Energy transfer; Green algae; Light; Light-Harvesting Protein Complexes - metabolism; Long-wavelength chlorophylls; Oxygen - metabolism; Photosynthesis; Photosystem I Protein Complex - metabolism; Photosystem II Protein Complex - metabolism; Prasiola crispa; Spectrometry, Fluorescence; Antarctic Regions; PAR; chl; LHC; MV; Green algae; LED; CET; OL and FL; PSI and PSII; Long-wavelength chlorophylls; Prasiola crispa; DCMU; LWC; LET; MES; Antarctica; Photosynthesis; Energy transfer
• ISSN: 0005-2728; 1879-2650
• DOI: 10.1016/j.bbabio.2019.148139

An aerial green alga, Prasiola crispa (Lightf.) Menegh, which is known to form large colonies in Antarctic habitats, is subject to severe environmental stresses due to low temperature, draught and strong sunlight in summer. A considerable light-absorption by long-wavelength chlorophylls (LWC) at around 710 nm, which seem to consist of chlorophyll a, was detected in thallus of P. crispa harvested at a terrestrial environment in Antarctica. Absorption level at 710 nm against that at 680 nm was correlated with fluorescence emission intensity at 713 nm at room temperature and the 77 K fluorescence emission band from LWC was found to be emitted at 735 nm. We demonstrated that the LWC efficiently transfer excitation energy to photosystem II (PSII) reaction center from measurements of action spectra of photosynthetic oxygen evolution and P700 photo-oxidation. The global quantum yield of PSII excitation in thallus by far-red light was shown to be as high as by orange light, and the excitation balance between PSII and PSI was almost same in the two light sources. It is thus proposed that the LWC increase the photosynthetic productivity in the lower parts of overlapping thalli and contribute to the predominance of alga in the severe environment. •A remarkable long-wavelength form of chlorophyll a was detected in P. crispa.•The long-wavelength chlorophylls efficiently transfer excitation energy to PSII.•P. crispa can photosynthesize with only far-red light by uphill energy transfer.•The primary electron donor of reaction center of PSI was ordinary P700.•The long-wavelength chlorophylls accompanying to PSII are independent from PSI.