Complex cells likely arose from the merger of an archaeal host cell with a bacterial cell some two billion years ago. As a consequence, many of the most conserved features of eukaryotic cell biology have their origins in archaea. It is not yet clear whether this includes cell cycle control machinery, since the close archaeal relatives of eukaryotes that possess an orderly cell cycle, lack CDK-cyclins. Similarly, while the recent discovery of the Asgard archaea as the closest living archaeal relatives of eukaryotes has promised to shed new light on the path of eukaryogenesis, it is not yet clear whether Asgard archaea have an ordered cell cycle, nor whether they express conserved cell cycle regulators.
To explore this question afresh, we will study the coupling between cell shape, DNA segregation and cell division in different Asgard archaeal lineages — following up on work we recently completed in Sulfolobus in which we discovered roles for cycic transcription, cyclic protein degradation, along with a division ring assembly checkpoint in cell cycle control. By employing a wide variety of methods, including anaerobic cell cultivation, live cell imaging, biochemistry along with phylogenetic methods, this work should reveal unique features of cell cycle control in the Asgard archaea, homologies between archaeal and eukaryotic cell cycle machinery, as well as core principles that underpin cell cycle control across systems.