Light-induced degradation of D2 protein in isolated photosystem II reaction center complex.
When isolated photosystem II reaction centers from spinach are exposed to photoinhibitory light in the presence of an electron acceptor, breakdown products of the D2 protein at 28, 25, 23, 18, 9, 5 and 4.5 kDa are detected by immunoblotting with a monospecific anti-D2 polyclonal antibody. In a time-course experiment the 23 and 4.5 kDa fragments show a transient appearance, whilst the others are photoaccumulated. The regions of the D2 protein containing the cleavage sites for the 28 and 18 kDa photoinduced fragments have been identified. Significant degradation of D2 takes place only in the presence of an electron acceptor, and breakdown of the protein is partially prevented by serine-type protease inhibitors.
Barbato
R
R
Dipartimento di Biologia dell'Università di Padova, Italy.
Friso
G
G
de Laureto
P P
PP
Frizzo
A
A
Rigoni
F
F
Giacometti
G M
GM
D000595:Amino Acid Sequence; D015153:Blotting, Western; D010450:Endopeptidases / Q000187:drug effects / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism*; D010775:Photic Stimulation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000302:isolation & purification / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D010944:Plants / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology
D010446:Peptide Fragments; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D015842:Serine Proteinase Inhibitors; D010450:Endopeptidases