Acclimation process of the chlorophyll d-bearing cyanobacterium Acaryochloris marina to an orange light environment revealed by transcriptomic analysis and electron microscopic observation

Tomonori Kashimoto, Keita Miyake, Mayuko Sato, Kaisei Maeda, Chikahiro Matsumoto, Masahiko Ikeuchi, Kiminori Toyooka, Satoru Watanabe, Yu Kanesaki, Rei Narikawa
2020 Journal of General and Applied Microbiology  
The cyanobacterium Acaryochloris marina MBIC 11017 (A. marina 11017) possesses chlorophyll d (Chl. d) peaking at 698 nm as photosystem reaction center pigments, instead of chlorophyll a (Chl. a) peaking at 665 nm. About 95% of the total chlorophylls is Chl. d in A. marina 11017. In addition, A. marina 11017 possesses phycobilisome (PBS) supercomplex to harvest orange light and to transfer the absorbing energy to the photosystems. In this context, A. marina 11017 utilizes both far-red and orange
more » ... light as the photosynthetic energy source. In the present study, we incubated A. marina 11017 cells under monochromatic orange and far-red light conditions and performed transcriptional and morphological studies by RNA-seq analysis and electron microscopy. Cellular absorption spectra, transcriptomic profiles, and microscopic observations demonstrated that PBS was highly accumulated under an orange light condition relative to a far-red light condition. Notably, transcription of one cpcBA operon encoding the phycobiliprotein of the phycocyanin was up-regulated under the orange light condition, but another operon was constitutively expressed under both conditions, indicating functional diversification of these two operons for light harvesting. Taking the other observations into consideration, we could illustrate the photoacclimation processes of A. marina 11017 in response to orange and far-red light conditions in detail.
doi:10.2323/jgam.2019.11.008 pmid:32147625 fatcat:ds5g2hfwvfcopkccpagawfhehu