Oral Presentation 18th International Congress on Photobiology 2024

Diversity and evolution of far-red light photoacclimation in cyanobacteria (#91)

Dennis Nürnberg 1
  1. FU Berlin, Berlin, BERLIN, Germany

The discovery of cyanobacteria capable of harvesting far-red light has changed the paradigm that oxygenic photosynthesis is only driven by visible light and exclusively by chlorophyll a. There are two known types of far-red photosynthesis. Firstly, a constitutive adaptation that uses a majority of chlorophyll d, which is restricted to a single genus (Acaryochloris). Moreover, an acclimation response, known as Far-Red Light Photoacclimation (FaRLiP), which uses chlorophyll f and is present in phylogenetically diverse cyanobacteria (1). FaRLiP involves the extensive remodelling of the photosynthetic machinery, via a cluster of approximately 19 genes coding for paralogous subunits of Photosystem I, Photosystem II, phycobilisomes and master control elements. Here, I will highlight the similarities and differences of FaRLiP among cyanobacteria on a cell, membrane, protein and DNA level by using bioinformatics, biochemical and biophysical methods. Our study focuses on cyanobacteria of the genus “Chroococcidiopsis” (2), as well as the phylogenetically early-branching group of “Halomicronema/Nodosilineales”. The latter group is especially underrepresented. We could increase the number of FaRLiP cyanobacteria among them by using stringent far-red cultivation methods on samples from the hypersaline environment of the Sebkha Ooum Dba (Morocco). This data enabled high-resolution phylogenetic work and supports that FaRLiP appeared early in cyanobacterial evolution (3). Furthermore, strains were discovered that only contain a partial FaRLiP clusters, without genes for a far-red PSI variant, but with a normal growth behaviour under far-red light (4) and without genes for a far-red PSII. These “outliers” have been characterised by biophysical and biochemical methods, raising the question of the minimal requirements for FaRLiP.

  1. Antonaru LA, Cardona T, Larkum AWD and Nürnberg DJ (2020) Global distribution of a chlorophyll f cyanobacterial marker. ISME J 14, 2275–2287.
  2. Antonaru LA, Selinger VM, Jung P, Di Stefano G, Sanderson ND, Barker L, Wilson DJ, Büdel B, Canniffe DP, Billi D and Nürnberg DJ (2024) Common loss of far-red light photoacclimation in cyanobacteria from hot and cold deserts: a case study in the Chroococcidiopsidales. ISME Commun; 3(1):113.
  3. Antonaru LA, Rad-Menéndez C, Mbedi S, Sparmann S, Pope M, Oliver T, Wu S, Green D, Gugger M and Nürnberg DJ (2024) The ancient evolution of far-red light photoacclimation in cyanobacteria. bioRxiv, doi.org/10.1101/2024.05.15.594131
  4. Billi D, Napoli A, Mosca C, Fagliarone C, de Carolis R, Balbi A, Scanu M, Selinger VM, Antonaru LA and Nürnberg DJ (2022) Identification of far-red light acclimation in an endolithic Chroococcidiopsis strain and associated genomic features: Implications for oxygenic photosynthesis on exoplanets. Front Microbiol, 13:933404.