title: The plastid division proteins, FtsZ1 and FtsZ2, differ in their biochemical properties and sub-plastidial localization.
abstract: Plastid division in higher plants is morphologically similar to bacterial cell division, with a process termed binary fission involving constriction of the envelope membranes. FtsZ proteins involved in bacterial division are also present in higher plants, in which the ftsZ genes belong to two distinct families: ftsZ1 and ftsZ2. However, the roles of the corresponding proteins FtsZ1 and FtsZ2 in plastid division have not been determined. Here we show that the expression of plant FtsZ1 and FtsZ2 in bacteria has different effects on cell division, and that distinct protein domains are involved in the process. We have studied the assembly of purified FtsZ1 and FtsZ2 using a chemical cross-linking approach followed by PAGE and electron microscopy analyses of the resulting polymers. This has revealed that FtsZ1 is capable of forming long rod-shaped polymers and rings similar to the bacterial FtsZ structures, whereas FtsZ2 does not form any organized polymer. Moreover, using purified sub-plastidial fractions, we show that both proteins are present in the stroma, and that a subset of FtsZ2 is tightly bound to the purified envelope membranes. These results indicate that FtsZ2 has a localization pattern distinct from that of FtsZ1, which can be related to distinct properties of the proteins. From the results presented here, we propose a model for the sequential topological localization and functions of green plant FtsZ1 and FtsZ2 in chloroplast division.
authors.affiliation: Laboratoire de Génétique Moléculaire des Plantes, UMR 5575, CNRS-Université Joseph Fourier, BP 53, 38041 Grenoble, Cedex, France.
authors.forename: El-Sayed
authors.initials: el-S
authors.lastname: El-Kafafi
authors.forename: Sunil
authors.initials: S
authors.lastname: Mukherjee
authors.forename: Mahmoud
authors.initials: M
authors.lastname: El-Shami
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Putaux
authors.forename: Maryse A
authors.initials: MA
authors.lastname: Block
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pignot-Paintrand
authors.forename: Silva
authors.initials: S
authors.lastname: Lerbs-Mache
authors.forename: Denis
authors.initials: D
authors.lastname: Falconet
mesh_terms: D029681:Arabidopsis Proteins; D002455:Cell Division / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology; D002736:Chloroplasts / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D030781:Organisms, Genetically Modified; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C095113:FTSZ protein, Arabidopsis; D010940:Plant Proteins