Publication Information
Wu et al., 2013
No external accession available
Abstract
Mol Cell Proteomics. 2013 Oct;12(10):2856-73. doi: 10.1074/mcp.M113.029579. Epub
2013 Jul 2.
Sucrose-induced receptor kinase SIRK1 regulates a plasma membrane aquaporin in
Arabidopsis.
Wu XN(1), Sanchez Rodriguez C, Pertl-Obermeyer H, Obermeyer G, Schulze WX.
Author information:
(1)Max Planck Institute for Molecular Plant Physiology, Am Mühlenberg 1, 14476
Golm, Germany;
The transmembrane receptor kinase family is the largest protein kinase family in
Arabidopsis, and it contains the highest fraction of proteins with yet
uncharacterized functions. Here, we present functions of SIRK1, a receptor
kinase that was previously identified with rapid transient phosphorylation after
sucrose resupply to sucrose-starved seedlings. SIRK1 was found to be an active
kinase with increasing activity in the presence of an external sucrose supply.
In sirk1 T-DNA insertional mutants, the sucrose-induced phosphorylation patterns
of several membrane proteins were strongly reduced; in particular, pore-gating
phosphorylation sites in aquaporins were affected. SIRK1-GFP fusions were found
to directly interact with aquaporins in affinity pull-down experiments on
microsomal membrane vesicles. Furthermore, protoplast swelling assays of sirk1
mutants and SIRK1-GFP expressing lines confirmed a direct functional interaction
of receptor kinase SIRK1 and aquaporins as substrates for phosphorylation. A
lack of SIRK1 expression resulted in the failure of mutant protoplasts to
control water channel activity upon changes in external sucrose concentrations.
We propose that SIRK1 is involved in the regulation of sucrose-specific osmotic
responses through direct interaction with and activation of an aquaporin via
phosphorylation and that the duration of this response is controlled by
phosphorylation-dependent receptor internalization.
DOI: 10.1074/mcp.M113.029579
PMCID: PMC3790296
PMID: 23820729 [Indexed for MEDLINE]
