Function of glutathione peroxidases in legume root nodules.
Glutathione peroxidases (Gpxs) are antioxidant enzymes not studied so far in legume nodules, despite the fact that reactive oxygen species are produced at different steps of the symbiosis. The function of two Gpxs that are highly expressed in nodules of the model legume Lotus japonicus was examined. Gene expression analysis, enzymatic and nitrosylation assays, yeast cell complementation, in situ mRNA hybridization, immunoelectron microscopy, and LjGpx-green fluorescent protein (GFP) fusions were used to characterize the enzymes and to localize each transcript and isoform in nodules. The LjGpx1 and LjGpx3 genes encode thioredoxin-dependent phospholipid hydroperoxidases and are differentially regulated in response to nitric oxide (NO) and hormones. LjGpx1 and LjGpx3 are nitrosylated in vitro or in plants treated with S-nitrosoglutathione (GSNO). Consistent with the modification of the peroxidatic cysteine of LjGpx3, in vitro assays demonstrated that this modification results in enzyme inhibition. The enzymes are highly expressed in the infected zone, but the LjGpx3 mRNA is also detected in the cortex and vascular bundles. LjGpx1 is localized to the plastids and nuclei, and LjGpx3 to the cytosol and endoplasmic reticulum. Based on yeast complementation experiments, both enzymes protect against oxidative stress, salt stress, and membrane damage. It is concluded that both LjGpxs perform major antioxidative functions in nodules, preventing lipid peroxidation and other oxidative processes at different subcellular sites of vascular and infected cells. The enzymes are probably involved in hormone and NO signalling, and may be regulated through nitrosylation of the peroxidatic cysteine essential for catalytic function.
Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), Apartado 13034, 50080 Zaragoza, Spain.
Manuel A
MA
Matamoros
Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), Apartado 13034, 50080 Zaragoza, Spain.
Ana
A
Saiz
Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), Apartado 13034, 50080 Zaragoza, Spain.
Maria
M
Peñuelas
Institut des Sciences du Végétal, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
Pilar
P
Bustos-Sanmamed
Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-CSIC, Camino de Vera, 46022 Valencia, Spain.
Jose M
JM
Mulet
Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-CSIC, Camino de Vera, 46022 Valencia, Spain.
Maria V
MV
Barja
Université de Lorraine, Interactions Arbres-Microorganismes, UMR1136, F-54500 Vandoeuvre-lès-Nancy, France INRA, Interactions Arbres-Microorganismes, UMR1136, F-54280 Champenoux, France.
Nicolas
N
Rouhier
Biochemistry and Physiology of Plants, W5-134, Bielefeld University, D-33501 Bielefeld, Germany.
Marten
M
Moore
The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK.
Euan K
EK
James
Biochemistry and Physiology of Plants, W5-134, Bielefeld University, D-33501 Bielefeld, Germany.
Karl-Josef
KJ
Dietz
Departamento de Nutrición Vegetal, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (CSIC), Apartado 13034, 50080 Zaragoza, Spain becana@eead.csic.es.
Manuel
M
Becana
D000975:Antioxidants / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005979:Glutathione Peroxidase / Q000235:genetics* / Q000378:metabolism; D000070116:Lotus / Q000235:genetics* / Q000378:metabolism; D030781:Organisms, Genetically Modified / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D053204:Root Nodules, Plant / Q000378:metabolism; D026422:S-Nitrosoglutathione / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism
D000975:Antioxidants; D010940:Plant Proteins; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D026422:S-Nitrosoglutathione; D005979:Glutathione Peroxidase
Antioxidants; Lotus japonicus; S-nitrosylation.; glutathione peroxidases; legume nodules; nitric oxide; reactive oxygen species