Arabidopsis thaliana plastidial methionine sulfoxide reductases B, MSRBs, account for most leaf peptide MSR activity and are essential for growth under environmental constraints through a role in the preservation of photosystem antennae

• Published in: The Plant journal : for cell and molecular biology Vol. 61; no. 2; pp. 271 - 282
• Main Authors: Laugier, Edith, Tarrago, Lionel, Vieira Dos Santos, Christina, Eymery, Françoise, Havaux, Michel, Rey, Pascal
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 2010; Blackwell Publishing Ltd; Blackwell; Wiley
• Subjects: Adaptation, Physiological - radiation effects; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biochemistry, Molecular Biology; Biological and medical sciences; Blotting, Western; Chlorophyll; Chlorophyll - metabolism; chloroplast; Chloroplasts; Chloroplasts - enzymology; environmental constraint; Fundamental and applied biological sciences. Psychology; Gene expression; Genotype; growth; Isoenzymes - genetics; Isoenzymes - metabolism; Leaves; Life Sciences; Light; Methionine - analogs & derivatives; Methionine - metabolism; methionine sulfoxide; methionine sulfoxide reductase; Methionine Sulfoxide Reductases - genetics; Methionine Sulfoxide Reductases - metabolism; Mutation; Peptides; Phenotype; Photosynthesis - radiation effects; Plant biology; Plant growth; Plant Leaves - enzymology; Plant Leaves - genetics; Plant Leaves - growth & development; Plant physiology and development; Plants, Genetically Modified; Plastids; Proteins; Substrate Specificity; Temperature; Vegetal Biology; methionine sulfoxide reductase; Peptides; Enzyme; Growth; Methionine; Plant leaf; methionine sulfoxide; Arabidopsis thaliana; Photosystem; Cruciferae; environmental constraint; Dicotyledones; Angiospermae; Sulfoxide; Environment; Spermatophyta; Oxidoreductases; Chloroplast; Reductase
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2009.04053.x

Methionine oxidation to methionine sulfoxide (MetSO) is reversed by two types of methionine sulfoxide reductases (MSRs), A and B, specific to MetSO S- and R-diastereomers, respectively. Two MSRB isoforms, MSRB1 and MSRB2, are present in chloroplasts of Arabidopsis thaliana. To assess their physiological role, we characterized Arabidopsis mutants knockout for the expression of MSRB1, MSRB2 or both genes. Measurements of MSR activity in leaf extracts revealed that the two plastidial MSRB enzymes account for the major part of leaf peptide MSR capacity. Under standard conditions of light and temperature, plants lacking one or both plastidial MSRBs do not exhibit any phenotype, regarding growth and development. In contrast, we observed that the concomitant absence of both proteins results in a reduced growth for plants cultivated under high light or low temperature. In contrast, double mutant lines restored for MSRB2 expression display no phenotype. Under environmental constraints, the MetSO level in leaf proteins is higher in plants lacking both plastidial MSRBs than in Wt plants. The absence of plastidial MSRBs is associated with an increased chlorophyll a/b ratio, a reduced content of Lhca1 and Lhcb1 proteins and an impaired photosynthetic performance. Finally, we show that MSRBs are able to use as substrates, oxidized cpSRP43 and cpSRP54, the two main components involved in the targeting of Lhc proteins to the thylakoids. We propose that plastidial MSRBs fulfil an essential function in maintaining vegetative growth of plants during environmental constraints, through a role in the preservation of photosynthetic antennae.