An Arabidopsis homolog of the bacterial cell division inhibitor SulA is involved in plastid division

Plastids have evolved from an endosymbiosis between a cyanobacterial symbiont and a eukaryotic host cell. Their division is mediated both by proteins of the host cell and conserved bacterial division proteins. Here, we identified a new component of the plastid division machinery, Arabidopsis thaliana SuIA. Disruption of its cyanobacterial homolog (SSWA) in Synechocystis and overexpression of an AtSuIA-green fluorescent protein fusion in Arabidopsis demonstrate that these genes are involved in cell and plastid division, respectively. Overexpression of AtSuIA inhibits plastid division in planta but rescues plastid division defects caused by overexpression of AtFtsZ1-1 and AtFtsZ2-1, demonstrating that its role in plastid division may involve an interaction with AtFtsZ1-1 and AtFtsZ2-1.