Identification of a regulatory phosphorylation site in the hinge 1 region of nitrate reductase from spinach (Spinacea oleracea) leaves.
Purified nitrate reductase (NR) from spinach leaves was phosphorylated in vitro by NR-inactivating kinase on Ser-543 which is located in the hinge 1 region between the molybdenum-cofactor and haem-binding domains. Phosphorylation of Ser-543 allowed NR to be inhibited by the inhibitor, NIP. Degraded NR preparations in which a proportion of the subunits had lost 45 amino acids from the N-terminus during purification could be phosphorylated by NR kinase on Ser-543, but could not subsequently be fully inhibited by NIP, suggesting a role for the N-terminal tail of NR in NIP binding.
Department of Biochemistry, University of Dundee, Scotland, UK.
P
P
Douglas
N
N
Morrice
C
C
MacKintosh
D000595:Amino Acid Sequence; D001665:Binding Sites; D008969:Molecular Sequence Data; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D018515:Plant Leaves / Q000201:enzymology; D011494:Protein Kinases / Q000378:metabolism; D018724:Spinacia oleracea / Q000201:enzymology*
D009565:Nitrate Reductases; D050901:Nitrate Reductase; D011494:Protein Kinases