MinD, a membrane-bound ATPase, recruits MinC to inhibit FtsZ polymerization at the non-division selleck screening library site [4, 5]. MinE forms a dynamic ring that undergoes a repetitive cycle of movement first to one pole and then to the opposite pole in the cell [6], and induces conformational

changes in membrane-bound MinD [7], which results in Ganetespib price release of MinC and conversion of membrane-bound MinD (MinD:ATP) to cytoplasmic MinD (MinD:ADP) [7]. This highly dynamic localization cycle of Min proteins inhibits FtsZ ring formation near cell ends and forces FtsZ and many other cell division proteins to assembly at the center of the cell [8]. FtsZ and Min proteins are conserved in a wide variety of bacteria, including cyanobacteria [9]. As endosymbionts in plant cells, chloroplasts have inherited many characters from their ancestor, cyanobacteria [10]. For example, FtsZ, MinD, MinE and ARC6 are chloroplast division proteins evolved from cyanobacteria cell division proteins [9]. Besides the similarity shared with their ancestors, some new characters were gained in these proteins during evolution. The FtsZ family in Arabidopsis includes AtFtsZ1, which lacks the conserved SHP099 C-terminal domain [11]; AtFtsZ2-1 and AtFtsZ2-2 [12], which are more similar to the FtsZ in cyanobacteria than other members [13]; and ARC3, which has a much less conserved GTPase domain of FtsZ and a later acquired C-terminal MORN repeat

domain [14]. All these FtsZ homologues can form a ring at the chloroplast division site [15, Lepirudin 16]. Similar to their homologues in bacteria, MinD and MinE in Arabidopsis have been shown to be involved in the positioning of the division site in chloroplasts [17–19]. Antisense suppression of AtMinD or a single mutation in AtMinD cause misplacement of the chloroplast division site in Arabidopsis [17, 20]. AtMinE antagonizes the function of AtMinD [19]. Overexpression of AtMinE

in Arabidopsis results in a phenotype similar to that caused by antisense suppression of AtMinD [19]. However, AtMinD has been shown to be localized to puncta in chloroplasts [20] and never been reported to oscillate. This is quite different from that of EcMinD in E. coli. To study the function of AtMinD, we expressed it in E. coli HL1 mutant which has a deletion of EcMinD and EcMinE and a minicell phenotype [21]. Surprisingly, the mutant phenotype was complemented. Similar to the localization in chloroplasts [20], AtMinD was localized to puncta at the poles in E. coli HL1 mutant without oscillation in the absence of EcMinE. We also confirmed that AtMinD can interact with EcMinC. AtMinD may function through EcMinC by prevent FtsZ polymerization at the polar regions of the cell. Our data suggest that the cell division of E. coli can occur at the midcell with a non-oscillating Min system which includes AtMinD and EcMinC and the working mechanism of AtMinD in chloroplasts may be different from that of EcMinD in E.