@article {six_marine_2021,
	title = {Marine Synechococcus  picocyanobacteria: Light utilization across latitudes},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {118},
	number = {38},
	year = {2021},
	note = {Publisher: National Academy of Sciences Section: Biological Sciences},
	abstract = {<p>The most ubiquitous cyanobacteria, Synechococcus, have colonized different marine thermal niches through the evolutionary specialization of lineages adapted to different ranges of temperature seawater. We used the strains of Synechococcus temperature ecotypes to study how light utilization has evolved in the function of temperature. The tropical Synechococcus (clade II) was unable to grow under 16 {\textdegree}C but, at temperatures \&gt;25 {\textdegree}C, induced very high growth rates that relied on a strong synthesis of the components of the photosynthetic machinery, leading to a large increase in photosystem cross-section and electron flux. By contrast, the Synechococcus adapted to subpolar habitats (clade I) grew more slowly but was able to cope with temperatures \&lt;10 {\textdegree}C. We show that growth at such temperatures was accompanied by a large increase of the photoprotection capacities using the orange carotenoid protein (OCP). Metagenomic analyzes revealed that Synechococcus natural communities show the highest prevalence of the ocp genes in low-temperature niches, whereas most tropical clade II Synechococcus have lost the gene. Moreover, bioinformatic analyzes suggested that the OCP variants of the two cold-adapted Synechococcus clades I and IV have undergone evolutionary convergence through the adaptation of the molecular flexibility. Our study points to an important role of temperature in the evolution of the OCP. We, furthermore, discuss the implications of the different metabolic cost of these physiological strategies on the competitiveness of Synechococcus in a warming ocean. This study can help improve the current hypotheses and models aimed at predicting the changes in ocean carbon fluxes in response to global warming.</p>
},
	keywords = {?? Invalid DOI, RCC2035, rcc2382, RCC2385, RCC2421, RCC2527, RCC2535, RCC2553, RCC2570, RCC515, rcc539, rcc752, rcc791, to add},
	issn = {0027-8424, 1091-6490},
	doi = {10.1073/pnas.2111300118},
	url = {http://www.pnas.org/content/118/38/e2111300118},
	author = {Six, Christophe and Ratin, Morgane and Marie, Dominique and Corre, Erwan}
}
@article {grebert_molecular_2021,
	title = {Molecular bases of an alternative dual-enzyme system for light color acclimation of marine \textit{Synechococcus cyanobacteria},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {118},
	number = {9},
	year = {2021},
	pages = {e2019715118},
	abstract = {<p>Marine Synechococcus cyanobacteria owe their ubiquity in part to the wide pigment diversity of their light-harvesting complexes. In open ocean waters, cells predominantly possess sophisticated antennae with rods composed of phycocyanin and two types of phycoerythrins (PEI and PEII). Some strains are specialized for harvesting either green or blue light, while others can dynamically modify their light absorption spectrum to match the dominant ambient color. This process, called type IV chromatic acclimation (CA4), has been linked to the presence of a small genomic island occurring in two configurations (CA4-A and CA4-B). While the CA4-A process has been partially characterized, the CA4-B process has remained an enigma. Here we characterize the function of two members of the phycobilin lyase E/F clan, MpeW and MpeQ, in Synechococcus sp. strain A15-62 and demonstrate their critical role in CA4-B. While MpeW, encoded in the CA4-B island and up-regulated in green light, attaches the green light-absorbing chromophore phycoerythrobilin to cysteine-83 of the PEII α-subunit in green light, MpeQ binds phycoerythrobilin and isomerizes it into the blue light-absorbing phycourobilin at the same site in blue light, reversing the relationship of MpeZ and MpeY in the CA4-A strain RS9916. Our data thus reveal key molecular differences between the two types of chromatic acclimaters, both highly abundant but occupying distinct complementary ecological niches in the ocean. They also support an evolutionary scenario whereby CA4-B island acquisition allowed former blue light specialists to become chromatic acclimaters, while former green light specialists would have acquired this capacity by gaining a CA4-A island.</p>
},
	keywords = {RCC2374, to add},
	issn = {0027-8424, 1091-6490},
	doi = {10.1073/pnas.2019715118},
	url = {http://www.pnas.org/lookup/doi/10.1073/pnas.2019715118},
	author = {Gr{\'e}bert, Th{\'e}ophile and Nguyen, Adam A. and Pokhrel, Suman and Joseph, Kes Lynn and Ratin, Morgane and Dufour, Louison and Chen, Bo and Haney, Allissa M. and Karty, Jonathan A. and Trinidad, Jonathan C. and Garczarek, Laurence and Schluchter, Wendy M. and Kehoe, David M. and Partensky, Fr{\'e}d{\'e}ric}
}
