The Arabidopsis PILZ group genes encode tubulin-folding cofactor orthologs required for cell division but not cell growth.
Plant microtubules are organized into specific cell cycle-dependent arrays that have been implicated in diverse cellular processes, including cell division and organized cell expansion. Mutations in four Arabidopsis genes collectively called the PILZ group result in lethal embryos that consist of one or a few grossly enlarged cells. The mutant embryos lack microtubules but not actin filaments. Whereas the cytokinesis-specific syntaxin KNOLLE is not localized properly, trafficking of the putative auxin efflux carrier PIN1 to the plasma membrane is normal. The four PILZ group genes were isolated by map-based cloning and are shown to encode orthologs of mammalian tubulin-folding cofactors (TFCs) C, D, and E, and associated small G-protein Arl2 that mediate the formation of alpha/beta-tubulin heterodimers in vitro. The TFC C ortholog, PORCINO, was detected in cytosolic protein complexes and did not colocalize with microtubules. Another gene with a related, although weaker, embryo-lethal phenotype, KIESEL, was shown to encode a TFC A ortholog. Our genetic ablation of microtubules shows their requirement in cell division and vesicle trafficking during cytokinesis, whereas cell growth is mediated by microtubule-independent vesicle trafficking to the plasma membrane during interphase.
Steinborn
Katharina
K
ZMBP, Entwicklungsgenetik, Universität Tübingen, D-72076 Tübingen, Germany.
Maulbetsch
Christoph
C
Priester
Bianca
B
Trautmann
Susanne
S
Pacher
Tobias
T
Geiges
Bernd
B
Küttner
Frank
F
Lepiniec
Loic
L
Stierhof
York-Dieter
YD
Schwarz
Heinz
H
Jürgens
Gerd
G
Mayer
Ulrike
U
D017360:Arabidopsis / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D003001:Cloning, Molecular; D003599:Cytoskeleton / Q000378:metabolism; D005804:Genes, Lethal; D017343:Genes, Plant / Q000235:genetics*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins; D008869:Microtubule-Associated Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D017510:Protein Folding; D021381:Protein Transport; D050765:Qa-SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D012639:Seeds / Q000378:metabolism / Q000648:ultrastructure; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014404:Tubulin / Q000378:metabolism
D029681:Arabidopsis Proteins; C097724:KNOLLE protein, Arabidopsis; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D008869:Microtubule-Associated Proteins; C116363:PIN1 protein, Arabidopsis; D050765:Qa-SNARE Proteins; C443671:RBL2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014404:Tubulin