Molecular mechanisms of acclimation to shaded environments via red-shifted chlorophyll-a-based light harvesting antennas in eukaryotic algae

Radek Litvína,b, David Bínaa,b, Miroslava Herbstováa,b, Zdenko Gardiana,b, František Váchaa,b
aInstitute of Plant Molecular Biology, Biology Centre CAS, Branišovská 31, 370 05 České Budějovice, Czech Reublic; bFaculty of Science, University of South Bohemia, Branišovská 1370, 370 05 České Budějovice, Czech Republic

Marine habitats with illumination spectrum influenced by heavy shading by chlorophyll-containing organisms are known to be frequently occupied by cyanobacteria with red-shifted chlorophylls such as Chl d or Chl f [1]. Here we summarize recent data from several eukaryotic algae which utilize Chl a-based light harvesting antennas of the LHC family to survive in shaded environments. Phylogenetically distant light-harvesting systems from diatom Phaeodactylum tricornutum [2], alveolate Chromera velia [3], and eustigmatophyte Trachydiscus minutus are presented. These data demonstrate convergent evolution of these intriguing systems in unrelated species.

While P. tricornutum and C. velia are marine organisms from cold and warm seas, T. minutus is a freshwater alga. The niche with red-enhanced illumination is therefore extended outside of the marine ecosystems also to land-based habitats. P. tricornutum and C. velia acclimate to red-enhanced illumination by synthesis of specific LHC-type proteins, presumably arranged in a trimeric form. T. minutus presents several oligomeric states of light-harvesting antennas, all of which are red-shifted. The building block appears to be a trimer with significant absorbance at ~ 695 nm. T. minutus is one of the few known heterokont (stramenopile) algae with complex oligomeric antenna arrangement.

References

[1] Y. Li and M. Chen, Functional Plant Biol. 2015, 42, 493.
[2] M. Herbstová, D. Bína, P. Koník, Z. Gardian, F. Vácha and R. Litvín, Biochim Biophys Acta  2015, 1847, 534-543.
[3] D. Bína, Z. Gardian, M. Herbstová, E. Kotabová, P. Koník, R. Litvín, O. Prášil, J. Tichý and F. Vácha, Biochim Biophys Acta 2014, 1837, 802-810.