title: A mechanism for reorientation of cortical microtubule arrays driven by microtubule severing.
abstract: Environmental and hormonal signals cause reorganization of microtubule arrays in higher plants, but the mechanisms driving these transitions have remained elusive. The organization of these arrays is required to direct morphogenesis. We discovered that microtubule severing by the protein katanin plays a crucial and unexpected role in the reorientation of cortical arrays, as triggered by blue light. Imaging and genetic experiments revealed that phototropin photoreceptors stimulate katanin-mediated severing specifically at microtubule intersections, leading to the generation of new microtubules at these locations. We show how this activity serves as the basis for a mechanism that amplifies microtubules orthogonal to the initial array, thereby driving array reorientation. Our observations show how severing is used constructively to build a new microtubule array.
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA.
authors.forename: Jelmer J
authors.initials: JJ
authors.lastname: Lindeboom
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nakamura
authors.forename: Anneke
authors.initials: A
authors.lastname: Hibbel
authors.forename: Kostya
authors.initials: K
authors.lastname: Shundyak
authors.forename: Ryan
authors.initials: R
authors.lastname: Gutierrez
authors.forename: Tijs
authors.initials: T
authors.lastname: Ketelaar
authors.forename: Anne Mie C
authors.initials: AM
authors.lastname: Emons
authors.forename: Bela M
authors.initials: BM
authors.lastname: Mulder
authors.forename: Viktor
authors.initials: V
authors.lastname: Kirik
authors.forename: David W
authors.initials: DW
authors.lastname: Ehrhardt
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018546:Hypocotyl / Q000378:metabolism / Q000648:ultrastructure; D000074201:Katanin; D008027:Light; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D010750:Phosphoproteins / Q000378:metabolism; D018524:Phototropism; D017346:Protein Serine-Threonine Kinases; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; C423903:PHOT2 protein, Arabidopsis; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; C103646:NPH1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D000251:Adenosine Triphosphatases; C436244:KTN1 protein, Arabidopsis; D000074201:Katanin