Publication Information
Wu et al., 2014
No external accession available
Abstract
J Proteome Res. 2014 Jul 3;13(7):3397-409. doi: 10.1021/pr5003164. Epub 2014 Jun
20.
A kinase-phosphatase signaling module with BSK8 and BSL2 involved in regulation
of sucrose-phosphate synthase.
Wu X(1), Sklodowski K, Encke B, Schulze WX.
Author information:
(1)Max Planck Institute for Molecular Plant Physiology , Am Mühlenberg 1, 14476
Golm, Germany.
External supply of sucrose to carbon-starved Arabidopsis seedlings induced
changes in phosphorylation of Brassinosteroid Signaling Kinase 8 (BSK8) at two
different sites. Serine S(20) lies within a phosphorylation hotspot at the
N-terminal region of the protein, while S(213) is located within the kinase
domain of BSK8. Upon sucrose supply phosphorylation of BSK8(S20) and BSK8(S213)
showed opposite behavior with increasing phosphorylation of S(213) and decreased
phosphorylation of S(20) at 5 min after sucrose supply. Here we aim to
systematically analyze the effects of BSK8 mutations on downstream cellular
regulatory events and characterize molecular functions of BSK8 and its
phosphorylation. Comparative phosphoproteomic profiling of a bsk8 knockout
mutant and wild type revealed potential targets in sucrose metabolism. Activity
of sucrose-phosphate synthase (SPS) was decreased by phosphorylation at S(152),
and SPS phosphorylation inversely correlated with sucrose-induced BSK8 activity.
Furthermore, BSK8 was found to interact with BSL2, a Kelch-type phosphatase. On
the basis of a combination of kinase activity measurements, SPS activity assays,
and phosphorylation site mutations in BSK8 at S(20) and S(213), we conclude that
regulation of SPS by BSK8 occurs through activation of a phosphatase that in
turn may dephosphorylate SPS and thus activates the enzyme.
DOI: 10.1021/pr5003164
PMID: 24924143 [Indexed for MEDLINE]
