title: Challenges to develop nitrogen-fixing cereals by direct nif-gene transfer.
abstract: Some regions of the developing world suffer low cereal production yields due to low fertilizer inputs, among other factors. Biological N2 fixation, catalyzed by the prokaryotic enzyme nitrogenase, is an alternative to the use of synthetic N fertilizers. The molybdenum nitrogenase is an O2-labile metalloenzyme composed of the NifDK and NifH proteins, which biosyntheses require a number of nif gene products. A challenging strategy to increase cereal crop productivity in a scenario of low N fertilization is the direct transfer of nif genes into cereals. The sensitivity of nitrogenase to O2 and the apparent complexity of nitrogenase biosynthesis are the main barriers identified so far. Expression of active NifH requires the products of nifM, nifH, and possibly nifU and nifS, whereas active NifDK requires the products of nifH, nifD, nifK, nifB, nifE, nifN, and possibly nifU, nifS, nifQ, nifV, nafY, nifW and nifZ. Plastids and mitochondria are potential subcellular locations for nitrogenase. Both could provide the ATP and electrons required for nitrogenase to function but they differ in their internal O2 levels and their ability to incorporate ammonium into amino acids.
authors.affiliation: Instituto de Investigaciones en Biodiversidad y Biotecnología - Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, Buenos Aires, Argentina; Fundación para Investigaciones Biológicas Aplicadas, Pozuelo de Alarcón, Madrid, Spain.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Curatti
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain. Electronic address: lm.rubio@upm.es.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Rubio
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D002523:Edible Grain / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D005810:Multigene Family; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation / Q000235:genetics*; D009591:Nitrogenase / Q000235:genetics* / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D030821:Plants, Genetically Modified
chemical_list: D001426:Bacterial Proteins; D010088:Oxidoreductases; D009591:Nitrogenase; C029130:nitrogenase reductase; D009584:Nitrogen
keywords: Cereals; Food security; Nif; Nitrogen fixation; Nitrogenase