Phosphosite charge rather than shootward localization determines OCTOPUS activity in root protophloem.

Détails

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Etat: Public
Version: de l'auteur
ID Serval
serval:BIB_9FFB648750A2
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Phosphosite charge rather than shootward localization determines OCTOPUS activity in root protophloem.
Périodique
Proceedings of the National Academy of Sciences of the United States of America
Auteur(s)
Breda A.S., Hazak O., Hardtke C.S.
ISSN
1091-6490 (Electronic)
ISSN-L
0027-8424
Statut éditorial
Publié
Date de publication
11/07/2017
Peer-reviewed
Oui
Volume
114
Numéro
28
Pages
E5721-E5730
Langue
anglais
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't
Publication Status: ppublish
Résumé
Polar cellular localization of proteins is often associated with their function and activity. In plants, relatively few polar-localized factors have been described. Among them, the plasma membrane-associated <i>Arabidopsis</i> proteins OCTOPUS (OPS) and BREVIS RADIX (BRX) display shootward and rootward polar localization, respectively, in developing root protophloem cells. Both <i>ops</i> and <i>brx</i> null mutants exhibit defects in protophloem differentiation. Here we show that <i>OPS</i> and <i>BRX</i> act genetically in parallel in this process, although <i>OPS</i> dosage increase mends defects caused by <i>brx</i> loss-of-function. OPS protein function is ancient and conserved in the most basal angiosperms; however, many highly conserved structural OPS features are not strictly required for OPS function. They include a BRASSINOSTEROID INSENSITIVE 2 (BIN2) interaction domain, which supposedly mediates gain-of-function effects obtained through ectopic OPS overexpression. However, engineering an increasingly positive charge in a critical phosphorylation site, S318, progressively amplifies OPS activity. Such hyperactive OPS versions can even complement the severe phenotype of <i>brx ops</i> double mutants, and the most active variants eventually trigger gain-of-function phenotypes. Finally, BRX-OPS as well as OPS-BRX fusion proteins localize to the rootward end of developing protophloem cells, but complement <i>ops</i> mutants as efficiently as shootward localized OPS. Thus, our results suggest that S318 phosphorylation status, rather than a predominantly shootward polar localization, is a primary determinant of OPS activity.
Mots-clé
Arabidopsis/metabolism, Arabidopsis Proteins/metabolism, Brassinosteroids/metabolism, Cell Membrane/metabolism, Gene Expression Regulation, Plant, Glucuronidase/metabolism, Glycogen Synthase Kinase 3/metabolism, Magnoliopsida/metabolism, Membrane Proteins/metabolism, Methylation, Mutation, Phenotype, Phloem/metabolism, Phosphopeptides/metabolism, Phosphorylation, Plant Roots/metabolism, Plant Shoots/metabolism, Transgenes, Amborella, BREVIS RADIX, GSK3, OCTOPUS, sieve element
Pubmed
Web of science
Open Access
Oui
Création de la notice
06/07/2017 16:44
Dernière modification de la notice
20/08/2019 15:06
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