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Descripción
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| One ambitious goal in plant biotechnology is the generation of cereals varieties that require little or no nitrogen input to achieve higher yields in a sustainable agricultural system. This goal could be achieved by engineering plants to fix their own nitrogen, i.e. by functional expression of bacterial nitrogen fixation (nif) genes in the plant (1,2). The most immediate obstacles this approach must overcome are the sensitivity of nitrogenase components towards O2 and the complexity of nitrogenase, which requires a large number of genetic parts to function optimally (3). We hypothesized that the mitochondrial matrix could provide a low O2 environment appropriate for the assembly and the activity of nitrogenase components. To test this hypothesis Saccharomyces cerevisiae was chosen as model eukaryotic cell for the following reasons: (i) the possibility to set different O2 levels during expression of nif proteins; (ii) its genetic amenability; and (iii) its well understood mitochondrially-located bacterial-like Fe-S cluster assembly machinery (4). Here, we show that aerobically grown S. cerevisiae expresses active nitrogenase Fe protein when the NifH polypeptide was targeted to the mitochondrial matrix together with the NifM maturase (5). Co-expression of NifH and NifM with Nif-specific Fe-S cluster biosynthetic proteins NifU and NifS was not required for Fe protein activity, demonstrating NifH ability to incorporate endogenous mitochondrial Fe-S clusters. In contrast, expression of active Fe protein in the cytosol required both anoxic growth conditions and co-expression of NifH and NifM with NifU and NifS. These results show the convenience of using mitochondria to host nitrogenase components, thus providing instrumental technology for the grand challenge of engineering N2-fixing cereals. | |
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Internacional
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Si |
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ISSN o ISBN
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00000000000000000 |
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Entidad relacionada
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Nacionalidad Entidad
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Sin nacionalidad |
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Lugar del congreso
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Budapest |