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Abstract EANA2025-108


Time-scaled proteome wide analysis of the desert cyanobacterium Chroococcidiopsis 010 under far-red light

Gabriele Rigano¹,², Giorgia Di Stefano¹, Joerg Doellinger³, Peter Lasch³, Andy Schneider³, Daniela Billi¹
¹Department of Biology, University of Rome Tor Vergata, Rome, Italy ²PhD programme in Space Science and Technology, University of Trento, Trento, Italy ³Robert Koch-Institute, Centre for Biological Threats and Special Pathogens,Proteomics and Spectroscopy (ZBS6), 13353 Berlin, Germany


Cyanobacteria are oxygenic photosynthetic prokaryotes that have adapted to most of the environmental niches present on Earth. Among the remarkable adaptations cyanobacteria are capable of, one stands out as Far-red light photoacclimation (FaRLiP), which is the capability to perform oxygenic photosynthesis using far-red light (wavelengths 700 - 780 nm) typically inaccessible to standard photosynthetic systems. This process involves a coordinated reorganization of the photosynthetic machinery, including the synthesis of chlorophyll f and the replacement of core subunits in photosystems I and II. From the astrobiological point of view, the study of these mechanisms is extremely valuable considering that the majority of the stars in our galaxy are M-stars that have a far-red and infrared peak light spectrum emission, employing that photosynthetic life could potentially inhabit planets in these systems. 

Chroococcidiopsis sp. CCMEE 010 is a particular member of this category of cyanobacteria, since it is the only one capable to date of Far-red light photoacclimation with a reduced gene cluster of ~15 genes instead of ~20. Characterizing the molecular mechanisms of FaRLiP is fundamental to progress our understanding of this phenomenon. For this reason, we investigated the comprehensive proteome of Chroococcidiopsis sp. CCMEE 010 grown under visible light and far-red light at different time points (2, 7 and 14 days) through Liquid-Chromatography and Tandem Mass Spectrometry (LC-MS/MS), differential expression analysis (DEA) and gene set enrichment analysis (GSEA).

Preliminary results show a common response in the comparison far-red light vs visible light across the different time points (FR vs VL 2 days, FR vs VL 7 days, FR vs VL 14 days) specifically characterized by the upregulation of “photosynthetic electron transport chain” enriched biological process (GO:0009767) and downregulation of “lipopolysaccharide biosynthetic process” and “peptidoglycan biosynthetic process” (GO:0009103, GO:0009252 respectively). Moreover, we observed a time-dependent upregulation of the proteins encoded by the FaRLiP cluster with increasing log2FC values in longer time exposures.                 

These results suggest a far-red light induced reorganization of the membrane/cell wall/lipopolysaccharide and of the photosynthetic apparatus in Chroococcidiopsis 010. This work will provide new insights in the process of far-red light photoacclimation in cyanobacteria and lay the foundations to future experiments in astrobiology as well as in space biotechnology.