“…Cyanobacterial PSI trimers have been reported in many published works (Boekema et al, 1987(Boekema et al, , 2001Almog et al, 1991;Kruip et al, 1993Kruip et al, , 1994Kruip et al, , 1997Tsiotis et al, 1995;Garczarek et al, 1998;Tucker and Sherman, 2000;Mangels et al, 2002;Bibby et al, 2003;Brecht et al, 2012), and the only existing crystal structure of a cyanobacterial PSI, from Thermosynechococcus elongatus BP-1 (Jordan et al, 2001), suggests that cyanobacteria PSI preferentially forms a trimer. Although there have been reports of trimeric forms of PSI in plants (Heinemeyer et al, 2004;Kouril et al, 2005), it is now widely accepted that plant PSI forms only monomeric complexes (Kitmitto et al, 1998;Kouril et al, 2005). Furthermore, it is known that PSI is a monomer in green and red algae (Gardian et al, 2007) as well as in diatoms (Veith and Büchel, 2007).…”