Building the GreenCut2 suite of proteins to unmask photosynthetic function and regulation

The suite of GreenCut proteins, initially assembled in 2007 and updated in 2011 (GreenCut2), comprises 597 Chlamydomonas reinhardtii proteins; these proteins, identified as putative orthologues in all green lineage organisms examined, but not (or poorly conserved) in non-photosynthetic organisms, are potentially enriched for proteins affiliated with photosynthesis. The annotation of GreenCut2 proteins and the characterization of mutants with lesions in genes encoding those proteins identified catalytic components of the photosynthetic apparatus that were previously uncharacterized, as well as polypeptides likely associated with chloroplast biogenesis and potential regulatory factors and activities that link environmental conditions to dynamic control of photosynthetic activities. Analyses of strains devoid of specific GreenCut2 proteins are being aided by a genome-wide library of mutants for which the lesions are mapped, indexed and readily available to the community (https://www.chlamylibrary.org/). In this review we briefly include some milestones in the history of photosynthesis, explain the way in which the GreenCut protein assemblage was generated and describe potential functions of individual member proteins, especially those linked to photosynthesis.