title: An atypical tubulin kinase mediates stress-induced microtubule depolymerization in Arabidopsis.
abstract: BACKGROUND
  As sessile organisms, plants adapt to adverse environmental conditions by quickly adjusting cell physiology and metabolism. Transient depolymerization of interphase microtubules is triggered by various acute stresses and biotic interactions with pathogenic organisms. Although rapid remodeling of plant microtubule arrays in response to external stresses is an intriguing phenomenon, the underlying molecular mechanisms and the advantages of this response to plant performance are poorly understood.
  
  
  RESULTS
  A domain with weak homology to the slime mold actin-fragmin kinase in the Arabidopsis mitogen-activated protein kinase phosphatase PROPYZAMIDE-HYPERSENSITIVE 1 (PHS1) is a Mn2+-dependent kinase. This atypical kinase domain phosphorylates Thr349 of α-tubulin at the longitudinal interdimer interface, thereby generating a polymerization-incompetent isoform, and effectively depolymerizes microtubule arrays when ectopically expressed in plant or animal cells. The intrinsic tubulin kinase activity is normally suppressed by the phosphatase activity of PHS1 but is unmasked immediately after osmotic stress. In the phs1 null mutant, stress-induced microtubule depolymerization does not occur.
  
  
  CONCLUSIONS
  The rapid and reversible modification of tubulin subunits by PHS1-mediated phosphorylation enables dynamic remodeling of the plant microtubule cytoskeleton in response to external stimuli. Suppression of the potent tubulin kinase activity by the juxtaposed phosphatase domain tightly controls this stress-activated microtubule regulator.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fujita
authors.forename: Jaromir
authors.initials: J
authors.lastname: Pytela
authors.forename: Takashi
authors.initials: T
authors.lastname: Hotta
authors.forename: Takehide
authors.initials: T
authors.lastname: Kato
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hamada
authors.forename: Rie
authors.initials: R
authors.lastname: Akamatsu
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Ishida
authors.forename: Natsumaro
authors.initials: N
authors.lastname: Kutsuna
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Hasezawa
authors.forename: Yuko
authors.initials: Y
authors.lastname: Nomura
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Nakagami
authors.forename: Takashi
authors.initials: T
authors.lastname: Hashimoto
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D054638:Dual Specificity Phosphatase 1 / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D009997:Osmotic Pressure; D010766:Phosphorylation; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D014404:Tubulin / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D014404:Tubulin; D010770:Phosphotransferases; D054638:Dual Specificity Phosphatase 1; C514675:PHS1 protein, Arabidopsis; D017027:Protein Tyrosine Phosphatases