Publication Information
Reiland et al., 2011
Abstract
Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):12955-60. doi:
10.1073/pnas.1104734108. Epub 2011 Jul 18.
Comparative phosphoproteome profiling reveals a function of the STN8 kinase in
fine-tuning of cyclic electron flow (CEF).
Reiland S(1), Finazzi G, Endler A, Willig A, Baerenfaller K, Grossmann J,
Gerrits B, Rutishauser D, Gruissem W, Rochaix JD, Baginsky S.
Author information:
(1)Department of Biology, Eidgenössische Technische Hochschule Zurich, 8092
Zurich, Switzerland.
Important aspects of photosynthetic electron transport efficiency in
chloroplasts are controlled by protein phosphorylation. Two thylakoid-associated
kinases, STN7 and STN8, have distinct roles in short- and long-term
photosynthetic acclimation to changes in light quality and quantity. Although
some substrates of STN7 and STN8 are known, the complexity of this regulatory
kinase system implies that currently unknown substrates connect photosynthetic
performance with the regulation of metabolic and regulatory functions. We
performed an unbiased phosphoproteome-wide screen with Arabidopsis WT and stn8
mutant plants to identify unique STN8 targets. The phosphorylation status of
STN7 was not affected in stn8, indicating that kinases other than STN8
phosphorylate STN7 under standard growth conditions. Among several putative STN8
substrates, PGRL1-A is of particular importance because of its possible role in
the modulation of cyclic electron transfer. The STN8 phosphorylation site on
PGRL1-A is absent in both monocotyledonous plants and algae. In dicots,
spectroscopic measurements with Arabidopsis WT, stn7, stn8, and stn7/stn8
double-mutant plants indicate a STN8-mediated slowing down of the transition
from cyclic to linear electron flow at the onset of illumination. This finding
suggests a possible link between protein phosphorylation by STN8 and fine-tuning
of cyclic electron flow during this critical step of photosynthesis, when the
carbon assimilation is not commensurate to the electron flow capacity of the
chloroplast.
DOI: 10.1073/pnas.1104734108
PMCID: PMC3150903
PMID: 21768351 [Indexed for MEDLINE]
Conflict of interest statement: The authors declare no conflict of interest.
