Project description:The transformation of endosymbiotic bacteria into genetically integrated organelles was central to eukaryote evolution. During organellogenesis, control over endosymbiont division, proteome composition, and physiology largely shifted from endosymbiont to nucleus. However, the order and timing of events underpinning this major evolutionary transition are poorly understood. Here, we identified by protein mass spectrometry seven nucleus-encoded proteins that are targeted to the endosymbiont.