title: Arabidopsis AUGMIN subunit8 is a microtubule plus-end binding protein that promotes microtubule reorientation in hypocotyls.
abstract: In plant cells, cortical microtubules provide tracks for cellulose-synthesizing enzymes and regulate cell division, growth, and morphogenesis. The role of microtubules in these essential cellular processes depends on the spatial arrangement of the microtubules. Cortical microtubules are reoriented in response to changes in cell growth status and cell shape. Therefore, an understanding of the mechanism that underlies the change in microtubule orientation will provide insight into plant cell growth and morphogenesis. This study demonstrated that AUGMIN subunit8 (AUG8) in Arabidopsis thaliana is a novel microtubule plus-end binding protein that participates in the reorientation of microtubules in hypocotyls when cell elongation slows down. AUG8 bound to the plus ends of microtubules and promoted tubulin polymerization in vitro. In vivo, AUG8 was recruited to the microtubule branch site immediately before nascent microtubules branched out. It specifically associated with the plus ends of growing cortical microtubules and regulated microtubule dynamics, which facilitated microtubule reorientation when microtubules changed their growth trajectory or encountered obstacle microtubules during microtubule reorientation. This study thus reveals a novel mechanism underlying microtubule reorientation that is critical for modulating cell elongation in Arabidopsis.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Lingyan
authors.initials: L
authors.lastname: Cao
authors.forename: Linhai
authors.initials: L
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Zheng
authors.forename: Hong
authors.initials: H
authors.lastname: Cao
authors.forename: Lian
authors.initials: L
authors.lastname: Ding
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Fu
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D009154:Mutation; D030821:Plants, Genetically Modified; D058105:Polymerization; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C586770:AUG8 protein, Arabidopsis; D029681:Arabidopsis Proteins; D008869:Microtubule-Associated Proteins; D049452:Green Fluorescent Proteins