A glycine to aspartic acid change in the MoCo domain of nitrate reductase reduces both activity and phosphorylation levels in Arabidopsis.

摘要: Nitrate reductase (NR), the first enzyme in nitrate assimilation pathway, is regulated post-transcriptionally response to light and CO2. In spinach, it has been shown that phosphorylation one mechanism mediates this regulation. paper, of NR Arabidopsis described both wild-type NR- mutant plants. A 110-kDa protein radiolabeled vivo with 32PO4 was immunoprecipitated anti-NR antibody from extracts plants but not which gene NIA2 had deleted. Phosphoamino acid phosphopeptide analysis showed that, as for phosphorylated on serine produces multiple phosphopeptides upon digestion CNBr or trypsin. Analysis three mutants lesions structural mutant, chl3-1, a reduced phenotype complemented by deletion mutant. Comparison sequences chl3-1 genes revealed single base mutation changing glycine codon an aspartic codon. This glycine, at position 308 MoCo domain NR, completely conserved all known eukaryotic sequences. Thus, required normal activity substitution residue disrupts processes, most likely altering conformation domain.