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Proc Natl Acad Sci U S A. 2016 Aug 2;113(31):E4567-76. doi: 10.1073/pnas.1604936113. Epub 2016 Jul 18.

Sensing and signaling of oxidative stress in chloroplasts by inactivation of the SAL1 phosphoadenosine phosphatase.

Author information

1
Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Acton, ACT 2601, Australia;
2
Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia;
3
Institute of Metabolism and Systems Research, University of Birmingham, Birmingham B15 2TT, United Kingdom; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham B15 2TH, United Kingdom;
4
Botanical Institute, Cluster of Excellence on Plant Sciences, University of Cologne, 50674 Cologne, Germany;
5
Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley, WA 6009, Australia.
6
Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Acton, ACT 2601, Australia; barry.pogson@anu.edu.au.

Abstract

Intracellular signaling during oxidative stress is complex, with organelle-to-nucleus retrograde communication pathways ill-defined or incomplete. Here we identify the 3'-phosphoadenosine 5'-phosphate (PAP) phosphatase SAL1 as a previously unidentified and conserved oxidative stress sensor in plant chloroplasts. Arabidopsis thaliana SAL1 (AtSAL1) senses changes in photosynthetic redox poise, hydrogen peroxide, and superoxide concentrations in chloroplasts via redox regulatory mechanisms. AtSAL1 phosphatase activity is suppressed by dimerization, intramolecular disulfide formation, and glutathionylation, allowing accumulation of its substrate, PAP, a chloroplast stress retrograde signal that regulates expression of plastid redox associated nuclear genes (PRANGs). This redox regulation of SAL1 for activation of chloroplast signaling is conserved in the plant kingdom, and the plant protein has evolved enhanced redox sensitivity compared with its yeast ortholog. Our results indicate that in addition to sulfur metabolism, SAL1 orthologs have evolved secondary functions in oxidative stress sensing in the plant kingdom.

KEYWORDS:

chloroplast; drought stress; redox regulation; retrograde signaling; stress sensing

PMID:
27432987
PMCID:
PMC4978270
DOI:
10.1073/pnas.1604936113
[Indexed for MEDLINE]
Free PMC Article

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