Plant nitrate reductase

H. Yamasaki and Y. Sakihama, Simultaneous production of nitric oxide and peroxynitrite by plant nitrate reductase in vitro evidence for the NR-dependent formation of active nitrogen species. FEBS Lett. 468, 89-92 (2000). 

Enzymes of the sulfite oxidase family, such as human sulfite oxidase, plant nitrate reductase, or the E. coli YedY protein (sulfite oxidase homologue) bind the MPT form of Moco (54) without further modification. So far, YedY represents the only molybdoenzyme isolated from E. coli that is characterized by the presence of the MPT... 

Notton B. A., and Hewitt, E. J. (1979). Structure and properties of higher plant nitrate reductase especially Spinacea oleracia. In Nitrogen Assimilation of Plants, ed. E. J. Hewitt and C. V. Cutting, pp. 227-44. London Academic Press. 

The sulfite oxidase enzymes are widespread in Nature, and are found in plants, bacteria (the sulfite dehydrogenases) and in birds and mammals. In addition, this family also includes the assimilatory plant nitrate reductases, which have essentially similar molybdenum coordination and differ structurally in lacking an active site arginine that is present in sulfite oxidase, and in showing somewhat different active site structures on turnover. We will focus here on the animal sulfite oxidase enzymes, of which chicken and human are the best studied. In animals the enzyme is responsible for the physiologically essential oxidation of sulfite to sulfate. It is a dimer of 52 kDa subunits and resides in the mitochondrial inner-membrane space. Each monomer contains Mo associated with one molybdopterin, plus a cytochrome heme. The enzymes catalyze the following reaction, which occurs at the Mo site which is reduced from Mo(vi) to Mo(iv) in the process ... 

Properties of Chlorella vulgaris and Some Higher Plant Nitrate Reductases (NRs)... 

It is not clear why some organisms have two 14-3-3 isoforms while others have up to 12. Binding 14-3-3 inhibits the plant enzyme nitrate reductase and there appears to be no selectivity between plant 14-3-3 isoforms in fact yeast and human isoforms appear to work equally as well in vitro. The best example where selectivity has been demonstrated is human 14-3-3o. 14-3-3o Preferential homodimerizes with itself and crystallization revealed a structural basis for this isoform s dimerization properties as well as for its specific selectivity for target binding proteins. Here partner specificity is the result of amino acid differences outside of the phosphopeptide-binding cleft. 

Mariotti, A., Mariotti, F., Champigny, M.L., Amarger, N. and Moyse, A. 1982 Nitrogen isotope fractionation associated with nitrate reductase activity and uptake of NO3by pearl millet. Plant Physiology 69 880-884. 

L. P. Solomonson and M. J. Barber, Assiinilatory nitrate reductase functional properties and regulation. Aimu. Rev. Plant Physiol. Mol. Biol. 41 225 (1990). 

M. A. Adams and P. M. Attiwill, Nitrate reductase activity and growth response of forest species to ammonium and nitrate sources of nitrogen. Plant Soil 66 373 (1982). 

Y. Sakihama, S. Nakamura, and H. Yamasaki, Nitric oxide production mediated by nitrate reductase in the green alga Chlamydomonas reinhardtii an alternative NO production pathway in photosynthetic organisms. Plant Cell Physiol. 43, 290-297 (2002). 

The method was extended from plants to include soils and waters by Milham ef al. (1970). They point out that nitrate reductase activity in fresh plant samples often causes a rapid decline in nitrate content, so samples collected from remote sites should be frozen in dry ice. A trace of chloroform was used to protect soil and water samples before freezing. We are now more aware of the harmful effects of chloroform inhalation and suggest immediate freezing without preservative and analysis within a few days as a safer alternative - especially with student projects. 

In plant leaves, nitrate reduction requires NADH produced by glycolytic activity (13), The ozone-induced depression of glycolytic metabolism in soybean leaves was also reflected in a depressed rate of nitrate reduction ( ), A single ozone exposure depressed the vivo nitrate reductase (NR) activity about 60% (Table III), To determine if ozone affected the NR protein directly, the in vitro NR activity was determined in leaf extracts from plants exposed to 0 and 980 pg/m ozone. 

The assimilatory nitrate reductase (Eq. 16-61) of fungi and green plants (Chapter 24) also belongs to the sulfite oxidase family. 

The opposite sequence, reduction of nitrate and nitrite ions, provides a major route of acquisition of ammonia for incorporation into cells by bacteria, fungi, and green plants (Fig. 24-1). Assimilatory (biosynthetic) nitrate reductases catalyze the two-electron reduction of nitrate to nitrite (Eq. 16-61). This is thought to occur at the molybdenum atom of the large 900-residue highly regulated793 molybdopterin-dependent enzyme. In green plants the reductant is... 

Nitrate reductases have been isolated from bacteria, plants and fungi and always contain molybdenum. Two types may be distinguished (a) the assimilatory nitrate reductases which catalyze the reduction of nitrate to nitrite, which ultimately is reduced to ammonia and used by... 

Fig. 1. The nitrate assimilation pathway in higher plants. The pathway of nitrate assimilation in the tobacco leaf is illustrated. In some other species an additional cytosolic GS is found in the leaf. The pathway in plant roots is more poorly documented and more variable GS in roots is mostly cytosolic, and some enzymes such as GOGAT are found as isoforms utilising alternate reducing substrates. T, expected nitrate carrier NR, nitrate reductase NiR, nitrite reductase GS, glutamine synthetase GOGAT, glutamate synthase Fd, ferredoxin Gin, glutamine Glu, glutamate.

Askerlund, P., Laurent, P., Nakagawa, H. Kader, J.-C. (1991). NADH-ferricyanide reductase of leaf plasma membranes. Partial purification and immunological relation to potato tuber microsomal NADH-ferricyanide reductase and spinach leaf NADH-nitrate reductase. Plant Physiology 95, 6-13. 

Caboche, M. Rouze, P. (1990). Nitrate reductase a target for molecular and cellular studies in higher plants. Trends in Genetics 6,187-92. 

Campbell, W.H. (1988). Nitrate reductase and its role in nitrate assimilation in plants. Physiologia Plantarum 74, 214-19. 

Campbell, W.H. Redinbaugh, M.G. (1984). Ferric-citrate reductase activity of nitrate reductase and its role in iron assimilation by plants. Journal of Plant Nutrition 7, 799-806. 

Cheng, C.-L., Acedo, G.N., Dewdney, J., Goodman, H.M. Con-kling, M.A. (1991). Differential expression of the two Arabidopsis nitrate reductase genes. Plant Physiology 96, 275-9. 

Ch6rel, I., Gonneau, M., Meyer, C., Pelsy, F. Caboche, M. (1990). Biochemical and immunological characterization of nitrate reductase-deficient nia mutants of Nicotiana plumbaginifolia. Plant Physiology 92, 659-65. 

Choi, H.K., Kleinhofs, A. An, G. (1989). Nucleotide sequence of rice nitrate reductase genes. Plant Molecular Biology 13, 731-3. 

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