Identification of the N-termini of NADPH : protochlorophyllide oxidoreductase A and B from barley etioplasts (Hordeum vulgare L.).
The N-termini of the NADPH : protochlorophyllide oxidoreductase (POR) proteins A and B from barley and POR from pea were determined by acetylation of the proteins and selective isolation of the N-terminal peptides for mass spectrometry de novo sequence analysis. We show that the cleavage sites between the transit peptides and the three mature POR proteins are homologous. The N-terminus in PORA is V48, that in PORB is A61, and that in POR from pea is E64. For the PORB protein, two additional N-termini were identified as A62 and A63, with decreased signal intensity of the corresponding N-terminal peptides. The results show that the transit peptide of PORA is considerably shorter than previously reported and predicted by ChloroP. A pentapeptide motif that has been characterized as responsible for binding of protochlorophyllide to the transit peptide of PORA [Reinbothe C, Pollmann S, Phetsarath-Faure P, Quigley F, Weisbeek P & Reinbothe S (2008) Plant Physiol148, 694-703] is shown here to be part of the mature PORA protein.
Plöscher
Matthias
M
Department of Biology I, Ludwig-Maximilians-University Munich, Germany.
Granvogl
Bernhard
B
Reisinger
Veronika
V
Eichacker
Lutz A
LA
D000107:Acetylation; D000595:Amino Acid Sequence; D001665:Binding Sites; D002736:Chloroplasts / Q000201:enzymology*; D001467:Hordeum / Q000201:enzymology*; D008969:Molecular Sequence Data; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry* / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D053719:Tandem Mass Spectrometry
D010940:Plant Proteins; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase