title: Phosphoprotein SAK1 is a regulator of acclimation to singlet oxygen in Chlamydomonas reinhardtii.
abstract: Singlet oxygen is a highly toxic and inevitable byproduct of oxygenic photosynthesis. The unicellular green alga Chlamydomonas reinhardtii is capable of acclimating specifically to singlet oxygen stress, but the retrograde signaling pathway from the chloroplast to the nucleus mediating this response is unknown. Here we describe a mutant, singlet oxygen acclimation knocked-out 1 (sak1), that lacks the acclimation response to singlet oxygen. Analysis of genome-wide changes in RNA abundance during acclimation to singlet oxygen revealed that SAK1 is a key regulator of the gene expression response during acclimation. The SAK1 gene encodes an uncharacterized protein with a domain conserved among chlorophytes and present in some bZIP transcription factors. The SAK1 protein is located in the cytosol, and it is induced and phosphorylated upon exposure to singlet oxygen, suggesting that it is a critical intermediate component of the retrograde signal transduction pathway leading to singlet oxygen acclimation.DOI: http://dx.doi.org/10.7554/eLife.02286.001.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States.
authors.forename: Setsuko
authors.initials: S
authors.lastname: Wakao
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Chin
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States.
authors.forename: Heidi K
authors.initials: HK
authors.lastname: Ledford
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Dent
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States.
authors.forename: David
authors.initials: D
authors.lastname: Casero
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, United States.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pellegrini
authors.affiliation: Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, United States Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, United States.
authors.forename: Sabeeha S
authors.initials: SS
authors.lastname: Merchant
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States niyogi@berkeley.edu.
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Niyogi
mesh_terms: D000222:Adaptation, Physiological; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D010750:Phosphoproteins / Q000378:metabolism*; D015398:Signal Transduction; D026082:Singlet Oxygen / Q000378:metabolism*
chemical_list: D010750:Phosphoproteins; D026082:Singlet Oxygen
keywords: chlamydomonas; photo-oxidative stress; photosynthesis; retrograde signaling; singlet oxygen