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Descripción
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| The generation of hydrogen (H2) as an obligate product of the reduction of atmospheric nitrogen (N2) is a source of inefficiency for the Rhizobium-legume symbiosis. Some diazotrophic bacteria, including some rhizobia, synthesize a H2 uptake system with a [NiFe] hydrogenase that catalyses the oxidation of this element, thus improving the energy efficiency of the biological nitrogen fixation and crop production. [NiFe]-hydrogenases are membrane-bound enzymes with two subunits. The large subunit (HupL) contains the catalytic site of the enzyme, a NiFe(CN-)2CO cofactor where nickel is coordinated by four conserved cysteinyl residues, two of which also coordinate the iron atom. The small subunit (HupS) harbours three FeS clusters through which electrons are transferred to their primary acceptor. A number of auxiliary proteins are involved in the biosynthesis and assembly of the [NiFe] cofactor into the large structural subunit. The final step in the maturation of this subunit involves a proteolytic processing by a nickel dependent protease (HupD) that removes a C-terminal peptide from HupL precursor (pre-HupL) (Böck et al, 2006). A structural model for pre-HupL has been built through computational modeling and molecular dynamics. In this model, the C-terminal tail of the protein behaves as an intrinsically disordered region. In addition, molecular dynamics simulations suggest that nickel might bind to the protein by two glutamate residues located in the N-terminal region (E27) and in the C-terminal tail (E589) in pre-HupL. Mutants affected in these residues were impaired in the processing of the structural subunit and, contrary to what it was observed in the wild type strain, the amount of processed form of HupL decreased in response to nickel addition to the medium. These results, together with structural modelling studies of HupL-HupD interaction, suggest that these two glutamates might be the initial site for nickel incorporation into the enzyme leading to an efficient processing by the protease (Albareda et al, 2019). | |
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Internacional
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Si |
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Nombre congreso
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VI Portuguese-Spanish Congress on Nitrogen Fixation XVII National Meeting of the Spanish Society of Nitrogen Fixation |
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Tipo de participación
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970 |
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Lugar del congreso
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Madrid |
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Revisores
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Si |
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ISBN o ISSN
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978-84-8344-705-5 |
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DOI
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Fecha inicio congreso
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10/06/2019 |
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Fecha fin congreso
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12/06/2019 |
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Desde la página
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72 |
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Hasta la página
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72 |
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Título de las actas
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Biological Nitrogen Fixation and Plant-Associated Microorganisms |