A light-induced protease from barley plastids degrades NADPH:protochlorophyllide oxidoreductase complexed with chlorophyllide.
The NADPH:protochlorophyllide oxidoreductase precursor protein (pPorA) of barley (Hordeum vulgare L. cv. Carina), synthesized from a full-length cDNA clone by coupling in vitro transcription and translation, is a catalytically active protein. It converts protochlorophyllide to chlorophyllide in a light- and NADPH-dependent manner. At least the pigment product of catalysis remains tightly bound to the precursor protein. The chlorophyllide-pPorA complex differs markedly from the protochlorophyllide-pPorA complex with respect to sensitivity to attack by a light-induced, nucleus-encoded, and energy-dependent protease activity of barley plastids. The pPorA-chlorophyllide complex is rapidly degraded, in contrast to pPorA-protochlorophyllide complexes containing or lacking NADPH, which are both resistant to protease treatment. Unexpectedly, pPorA devoid of its substrates or products was less sensitive to proteolysis than the pPorA-chlorophyllide complex, suggesting that both substrate binding and product formation during catalysis had caused differential changes in protein conformation.
Reinbothe
C
C
Department of Genetics, Swiss Federal Institute of Technology, Zurich, Switzerland.
Apel
K
K
Reinbothe
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S
D000255:Adenosine Triphosphate / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology*; D010450:Endopeptidases / Q000096:biosynthesis / Q000378:metabolism*; D004790:Enzyme Induction / Q000528:radiation effects; D017343:Genes, Plant; D001467:Hordeum / Q000201:enzymology*; D008027:Light; D010088:Oxidoreductases / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010940:Plant Proteins / Q000378:metabolism*; D011521:Protochlorophyllide / Q000378:metabolism
D010940:Plant Proteins; D011521:Protochlorophyllide; D000255:Adenosine Triphosphate; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase; D010450:Endopeptidases