“…In the latter, Rubisco amount was decreased by one third, followed by a default in carboxysome formation, resulting in reduced cell growth in air (Huang et al, 2020). Interestingly, while both RAF1 and RBCX appear as non-essential in cyanobacteria and seem to be able to interact in vitro with LSU oligomers of the same order, their mode of action may be different: the resolution of LSU-containing crystals (Bracher et al, 2011;Hauser et al, 2015;Huang et al, 2020;Xia et al, 2020) indicates indeed that RBCX and RAF1 have different binding sites on LSU, and may work sequentially, as RAF1 is able to displace RBCX from LSU while the converse is not true (Kolesinski et al, 2017). Secondly, the respective knock-outs observed in cyanobacteria exhibit different phenotypes regarding Rubisco amount and carboxysome formation, casting doubts about their possible redundancy (Huang et al, 2019;Huang et al, 2020).…”