Diversity and evolution of far-red light photoacclimation in cyanobacteria (#91)
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.
- Antonaru LA, Cardona T, Larkum AWD and Nürnberg DJ (2020) Global distribution of a chlorophyll f cyanobacterial marker. ISME J 14, 2275–2287.
- 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.
- 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
- 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.