Analysis of cDNA clones encoding the entire precursor-polypeptide for ferredoxin:NADP+ oxidoreductase from spinach

In this paper, we report the structural characterization of several spinach ferredoxin-NADP+ oxidoreductase (FNR) cDNAs ranging in size from 0.9 to 1.5 kilobases. A comparison of the deduced amino acid sequence with the known amino acid sequence determined for the spinach protein establishes that 1.4-1.5 kpb inserts span the full length of the mature protein (314 amino acid residues; Mr = 35,382). These also include an N-terminal 55 amino acid transit peptide as well as maximally 171 and 214 nucleotide 5' and 3' untranslated sequences, respectively. Evidence has been obtained that various forms of FNR arise from at least two similar genes. The FNR precursor (369 amino acid residues) has a calculated molecular mass of 41.2 kDa. Comparison of the transit peptide with transit peptides from two other stromal proteins shows little similarity at the level of primary sequence but some common features in secondary structure predictions.