title: Effects of mutations in Arabidopsis FtsZ1 on plastid division, FtsZ ring formation and positioning, and FtsZ filament morphology in vivo.
abstract: In plants, chloroplast division FtsZ proteins have diverged into two families, FtsZ1 and FtsZ2. FtsZ1 is more divergent from its bacterial counterparts and lacks a C-terminal motif conserved in most other FtsZs. To begin investigating FtsZ1 structure-function relationships, we first identified a T-DNA insertion mutation in the single FtsZ1 gene in Arabidopsis thaliana, AtFtsZ1-1. Homozygotes null for FtsZ1, though impaired in chloroplast division, could be isolated and set seed normally, indicating that FtsZ1 is not essential for viability. We then mapped five additional atftsZ1-1 alleles onto an FtsZ1 structural model and characterized chloroplast morphologies, FtsZ protein levels and FtsZ filament morphologies in young and mature leaves of the corresponding mutants. atftsZ1-1(G267R), atftsZ1-1(R298Q) and atftsZ1-1(Delta404-433) exhibit reduced FtsZ1 accumulation but wild-type FtsZ2 levels. The semi-dominant atftsZ1-1(G267R) mutation caused the most severe phenotype, altering a conserved residue in the predicted T7 loop. atftsZ1-1(G267R) protein accumulates normally in young leaves but is not detected in rings or filaments. atftsZ1-1(R298Q) has midplastid FtsZ1-containing rings in young leaves, indicating that R298 is not critical for ring formation or positioning despite its conservation. atftsZ1-1(D159N) and atftsZ1-1(G366A) both have overly long, sometimes spiral-like FtsZ filaments, suggesting that FtsZ dynamics are altered in these mutants. However, atftsZ1-1(D159N) exhibits loss of proper midplastid FtsZ positioning while atftsZ1-1(G366A) does not. Finally, truncation of the FtsZ1 C-terminus in atftsZ1-1(Delta404-433) impairs chloroplast division somewhat but does not prevent midplastid Z ring formation. These alleles will facilitate understanding of how the in vitro biochemical properties of FtsZ1 are related to its in vivo function.
authors.affiliation: Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Yoder
authors.forename: Deena
authors.initials: D
authors.lastname: Kadirjan-Kalbach
authors.forename: Bradley J S C
authors.initials: BJ
authors.lastname: Olson
authors.forename: Shin-Ya
authors.initials: SY
authors.lastname: Miyagishima
authors.forename: Stacy L
authors.initials: SL
authors.lastname: Deblasio
authors.forename: Roger P
authors.initials: RP
authors.lastname: Hangarter
authors.forename: Katherine W
authors.initials: KW
authors.lastname: Osteryoung
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D018515:Plant Leaves / Q000378:metabolism; D018087:Plastids / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D029681:Arabidopsis Proteins; C523306:FtsZ1 protein, Arabidopsis