Abstract
Through the evolution of eukaryote, division machineries of endosymbiont organelles plastid and mitochondria have been developed into amalgamation of bacterial division system and host eukaryotic controller. Despite differences in roles and morphology of the organelles, recent studies have revealed that these organelles have developed very similar division mechanisms, composed of three rings, in the early stage of evolution. A primitive red alga Cyanidioschyzon merolae has been established as a basic model of organelle division, whose organelles exhibit simplest morphology, synchronized division as well as observable division apparatuses; plastid dividing (PD) ring or mitochondrion dividing (MD) ring. In addition to the rings, the both organelles emplay two GTPases, FtsZ of bacterial remnant and eukaryotic dynamin as distinct dividing rings. Through detailed localizing studies of these proteins and apparatuses, roles of, FtsZ, PD or MD, and dynamin are thought to be placement, constriction and severance at division site, respectively.
