Abstract
Summary: Mitochondrial and chloroplast division controls the number and morphology of organelles, but how cells regulate organelle division remains to be clarified. Here, we show that each step of mitochondrial and chloroplast division is closely associated with the cell cycle in Cyanidioschyzon merolae. Electron microscopy revealed direct associations between the spindle pole bodies and mitochondria, suggesting that mitochondrial distribution is physically coupled with mitosis. Mitochondrial final severance was suppressed during S phase and once induced in M phase, when dynamin was specifically recruited. Although microtubule was not directly required for the organelles division, spatial interaction between microtubule and dynamin implied to be working on a possible checkpoint for spindle elongation. Chloroplast division was induced during S phase and suppressed during M phase, which was thought to be as a consequence of synthesis and degradation of dynamin and FtsZ. Molecular networks between cell cycle and the organelles division is discussed.
