title: Identification of the N-termini of NADPH : protochlorophyllide oxidoreductase A and B from barley etioplasts (Hordeum vulgare L.).
abstract: 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.
authors.affiliation: Department of Biology I, Ludwig-Maximilians-University Munich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Plöscher
authors.forename: Bernhard
authors.initials: B
authors.lastname: Granvogl
authors.forename: Veronika
authors.initials: V
authors.lastname: Reisinger
authors.forename: Lutz A
authors.initials: LA
authors.lastname: Eichacker
mesh_terms: 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
chemical_list: D010940:Plant Proteins; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase