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Functional Characterization and Expression of a Cytosolic Iron-Superoxide Dismutase from Cowpea Root Nodules

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dc.creator Morán, José F.
dc.creator James, Euan Kevin
dc.creator Rubio Luna, María Carmen
dc.creator Sarath, Gautam
dc.creator Klucas, R. V.
dc.creator Becana Ausejo, Manuel
dc.date 2008-06-11T10:18:13Z
dc.date 2008-06-11T10:18:13Z
dc.date 2003-09
dc.date.accessioned 2017-01-31T01:39:18Z
dc.date.available 2017-01-31T01:39:18Z
dc.identifier Plant Physiology 133:773-782 (2003)
dc.identifier 0032-0889
dc.identifier http://hdl.handle.net/10261/4988
dc.identifier 10.1104/pp.103.023010
dc.identifier.uri http://dspace.mediu.edu.my:8181/xmlui/handle/10261/4988
dc.description An iron-superoxide dismutase (FeSOD) with an unusual subcellular localization, VuFeSOD, has been purified from cowpea (Vigna unguiculata) nodules and leaves. The enzyme has two identical subunits of 27 kD that are not covalently bound. Comparison of its N-terminal sequence (NVAGINLL) with the cDNA-derived amino acid sequence showed that VuFeSOD is synthesized as a precursor with seven additional amino acids. The mature protein was overexpressed in Escherichia coli, and the recombinant enzyme was used to generate a polyclonal monospecific antibody. Phylogenetic and immunological data demonstrate that there are at least two types of FeSODs in plants. An enzyme homologous to VuFeSOD is present in soybean (Glycine max) and common bean (Phaseolus vulgaris) nodules but not in alfalfa (Medicago sativa) and pea (Pisum sativum) nodules. The latter two species also contain FeSODs in the leaves and nodules, but the enzymes are presumably localized to the chloroplasts and plastids. In contrast, immunoblots of the soluble nodule fraction and immunoelectron microscopy of cryo-processed nodule sections demonstrate that VuFeSOD is localized to the cytosol. Immunoblot analysis showed that the content of VuFeSOD protein increases in senescent nodules with active leghemoglobin degradation, suggesting a direct or indirect (free radical-mediated) role of the released Fe in enzyme induction. Therefore, contrary to the widely held view, FeSODs in plants are not restricted to the chloroplasts and may become an important defensive mechanism against the oxidative stress associated with senescence.
dc.description This work was supported by the Dirección General de Investigación (Ministerio de Ciencia y Tecnología, Spain; grant nos. PB98–0522 and AGL2002–02876). J.F.M. and M.C.R. were the recipients, respectively, of a postdoctoral contract and a postdoctoral fellowship funded by the Ministerio de Ciencia y Tecnología-European Union (I3P program).
dc.description Peer reviewed
dc.format 21359 bytes
dc.format application/pdf
dc.language eng
dc.publisher American Society of Plant Biologists
dc.rights closedAccess
dc.title Functional Characterization and Expression of a Cytosolic Iron-Superoxide Dismutase from Cowpea Root Nodules
dc.type Artículo

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