The outer plastid envelope protein Oep16: role as precursor translocase in import of protochlorophyllide oxidoreductase A.
A 16-kDa plastid envelope protein was identified by chemical crosslinking that interacts with the precursor of NADPH:protochlorophyllide oxdidoreductase A (pPORA) during its posttranslational import into isolated barley chloroplasts. Protein purification and subsequent protein sequencing showed that the 16-kDa protein is an ortholog of a previously identified outer plastid envelope protein, Oep16. A protein of identical size was present in barley etioplasts and interacted with pPORA. Similar 16-kDa protein-dependent crosslink products of pPORA were detected in wheat, pea, and Arabidopsis chloroplasts. Database analyses revealed that the 16-kDa protein belongs to a family of preprotein and amino acid transporters found in free-living bacteria and endosymbiotic mitochondria and chloroplasts. Antibodies raised against the 16-kDa protein inhibited import of pPORA, highlighting its role in protein import.
Reinbothe
Steffen
S
Université Joseph Fourier et Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5575, BP53, F-38041 Grenoble Cedex 9, France. steffen.reinbothe@ujf-grenoble.fr
Quigley
Françoise
F
Springer
Armin
A
Schemenewitz
Andreas
A
Reinbothe
Christiane
C
D000595:Amino Acid Sequence; D060365:Chloroplast Proteins; D003432:Cross-Linking Reagents; D019143:Evolution, Molecular; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism*; D007473:Ion Channels / Q000737:chemistry / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism*; D059828:Plant Cells; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D010944:Plants / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D018087:Plastids / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport
D060365:Chloroplast Proteins; D003432:Cross-Linking Reagents; D007473:Ion Channels; D026901:Membrane Transport Proteins; D010940:Plant Proteins; D011498:Protein Precursors; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase