Acaryochloris marina
| Acaryochloris marina | ||||||||||
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| Systematics | ||||||||||
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| Scientific name of the family | ||||||||||
| Acaryochloridaceae | ||||||||||
| J.Komárek, J.Kastovsky, J.Mares & JRJohansen | ||||||||||
| Scientific name of the genus | ||||||||||
| Acaryochloris | ||||||||||
| H.Miyashita & M.Chihara | ||||||||||
| Scientific name of the species | ||||||||||
| Acaryochloris marina | ||||||||||
| H. Miyashita & M. Chihara |
Acaryochloris marina is a cyanobacterium (a "blue alga ") and the only known photosynthetic life form with chlorophyll d as the main pigment .
Acaryochloris marina was isolated in 1993 from sea squirts caught near Palau and described as a new species in 2003 (according to other sources it was not discovered until 1996). It shows a so far unique molecular composition of the light-collecting antenna system ( light-collecting complex ).
All photosynthetic organisms have light-collecting complexes of proteins and pigments (chlorophyll) within the thylakoid membrane . These antenna systems absorb light and pass the absorbed light energy on to the photochemical reaction center. Cyanobacteria also have antenna complexes outside the membrane, which usually do not contain chlorophyll, but so-called phycobilin dyes in protein complexes, which also absorb green light.
While higher plants and other cyanobacteria predominantly contain chlorophyll a and b as the main pigments of the membrane-internal light harvesting complex (LHC), the LHC of A. marina contains almost exclusively chlorophyll d. In the case of chlorophyll d, the long-wave absorption band is red-shifted by more than 30 nm compared to chlorophyll a and chlorophyll b. This enables A. marina to use the near infrared range of sunlight for photosynthesis and to live together in a small space in symbiosis with other cyanobacteria. The phycobiliprotein antenna (PBP antenna) outside the membrane in A. marina also has a different structure than that of typical cyanobacteria.
Acaryochloris marina shares an ascidia as symbiont with Prochloron didemni in the Great Barrier Reef off the coast of Australia . The optical properties of each of the three organisms play an important role. While the heterotrophic (not photosynthetic) ascidia absorbs UV radiation and thereby the sensitive photosynthetic systems of the cyanobacteria are protected, prochloron with chlorophyll-a antennas primarily uses light in the wavelength range around 674 nm. The chlorophyll d of A. marina , on the other hand, pre-absorbs all light between 700 nm and 730 nm. The available light below 650 nm, which is also only weakly absorbed by prochloron , can stimulate the phycobiliprotein antenna of A. marina . Thus, the electromagnetic spectrum between 600 and 730 nm is optimally used through this symbiosis.
literature
- H. Miyashita, H. Ikemoto, N. Kurano, K. Adachi, M. Chihara, S. Miyachi: Chlorophyll d as a major pigment , Nature (London), 383, 402 (1996)
- J. Marquardt, H. Senger, H. Miyashita, S. Miyachi, E. Mörschel: Isolation and Characterization of phycobiliprotein aggregates from Acaryochloris marina, a prochloron like prokaryote containing mainly chlorophyll d . FEBS Lett 410, 428-432 (1997)
- Q. Hu, H. Miyashita, I. Iwasaki, N. Kurano, S. Miyachi, M. Iwaki, S. Itoh: A Photosystem I reaction center driven by chlorophyll d in oxygenic photosynthesis , Proc. Natl. Acad. Sci. Plant Biology, Vol 95, 13319-13323 (1998)
- Z. Petrášek, F.-J. Schmitt, Ch. Theiss, J. Huyer, M. Chen. A. Larkum, HJ Eichler, K. Kemnitz, H.-J. Eckert: Excitation energy transfer from Phycobiliprotein to Chlorophyll d in intact cells of "Acaryochloris marina" studied by time and wavelength resolved fluorescence spectroscopy , Photochem. Photobiol. Sci., 4, 1016-1022 (2005)
- F.-J. Schmitt, C. Theiss, K. Wache, J. Fuesers, S. Andree, A. Handojo, A. Karradt, D. Kiekebusch, HJ Eichler, H.-J Eckert: Investigation of the excited states dynamics in the Chl d- containing cyanobacterium "Acaryochloris marina" by time- and wavelength correlated single-photon counting , Proc. SPIE Vol. 6386, 638607 (2006)
Individual evidence
- ↑ Algaebase entry Acaryochloris marina H. Miyashita & M. Chihara