TY  - JOUR
A1  - Liu, Qinsong
A1  - Vain, Thomas
A1  - Viotti, Corrado
A1  - Doyle, Siamsa M.
A1  - Tarkowska, Danuse
A1  - Novak, Ondrej
A1  - Zipfel, Cyril
A1  - Sitbon, Folke
A1  - Robert, Stephanie
A1  - Hofius, Daniel
T1  - Vacuole integrity maintained by DUF300 proteins is required for brassinosteroid signaling regulation
JF  - Molecular plant
N2  - Brassinosteroid (BR) hormone signaling controls multiple processes during plant growth and development and is initiated at the plasma membrane through the receptor kinase BRASSINOSTEROID INSENSITIVE1 (BRI1) together with co-receptors such as BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). BRI1 abundance is regulated by endosomal recycling and vacuolar targeting, but the role of vacuole-related proteins in BR receptor dynamics and BR responses remains elusive. Here, we show that the absence of two DUF300 domain-containing tonoplast proteins, LAZARUS1 (LAZ1) and LAZ1 HOMOLOG1 (LAZ1H1), causes vacuole morphology defects, growth inhibition, and constitutive activation of BR signaling. Intriguingly, tonoplast accumulation of BAK1 was substantially increased and appeared causally linked to enhanced BRI1 trafficking and degradation in laz1 laz1h1 plants. Since unrelated vacuole mutants exhibited normal BR responses, our findings indicate that DUF300 proteins play distinct roles in the regulation of BR signaling by maintaining vacuole integrity required to balance subcellular BAK1 pools and BR receptor distribution.
KW  - brassinosteroid signaling
KW  - vacuole integrity
KW  - DUF300 proteins
KW  - tonoplast
KW  - Arabidopsis
Y1  - 2018
U6  - https://doi.org/10.1016/j.molp.2017.12.015
SN  - 1674-2052
SN  - 1752-9867
VL  - 11
IS  - 4
SP  - 553
EP  - 567
PB  - Cell Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Rocchetti, Alessandra
A1  - Sharma, Tripti
A1  - Wulfetange, Camilla
A1  - Scholz-Starke, Joachim
A1  - Grippa, Alexandra
A1  - Carpaneto, Armando
A1  - Dreyer, Ingo
A1  - Vitale, Alessandro
A1  - Czempinski, Katrin
A1  - Pedrazzini, Emanuela
T1  - The putative K+ channel subunit AtKCO3 forms stable dimers in arabidopsis
JF  - Frontiers in plant science
N2  - The permeation pore of K+ channels is formed by four copies of the pore domain. AtKCO3 is the only putative voltage-independent K+ channel subunit of Arabidopsis thaliana with a single pore domain. KCO3-like proteins recently emerged in evolution and, to date, have been found only in the genus Arabidopsis (A. thaliana and A. lyrata). We show that the absence of KCO3 does not cause marked changes in growth under various conditions. Only under osmotic stress we observed reduced root growth of the kco3-1 null-allele line. This phenotype was complemented by expressing a KCO3 mutant with an inactive pore, indicating that the function of KCO3 under osmotic stress does not depend on its direct ability to transport ions. Constitutively overexpressed AtKCO3 or AtKCO3::G FP are efficiently sorted to the tonoplast indicating that the protein is approved by the endoplasmic reticulum quality control. However, vacuoles isolated from transgenic plants do not have significant alterations in current density. Consistently, both AtKCO3 and AtKCO3::GFP are detected as homodimers upon velocity gradient centrifugation, an assembly state that would not allow for activity. We conclude that if AtKCO3 ever functions as a K+ channel, active tetramers are held by particularly weak interactions, are formed only in unknown specific conditions and may require partner proteins.
KW  - Arabidopsis
KW  - membrane proteins
KW  - potassium channels
KW  - protein assembly
KW  - tonoplast
Y1  - 2012
U6  - https://doi.org/10.3389/fpls.2012.00251
SN  - 1664-462X
VL  - 3
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  -