Interaction of carbonyl cyanide m-chlorophenylhydrazone with the photosystem II acceptor side

• Published in: FEBS letters 1993-04, Vol.320 (2), p.118-120
• Main Authors: Samuilov, Vitaly D., Barsky, Eugene L.
• Format: Article
• Language: English
• Subjects: (Mn)4, the tetranuclear Mn cluster of water-splitting complex Y; ADRY agent; ADRY, acceleration of the deactivation reactions of the water-splitting enzyme system Y; Carbonyl Cyanide m-Chlorophenyl Hydrazone - metabolism; Carbonyl Cyanide m-Chlorophenyl Hydrazone - pharmacology; CCCP; CCCP, carbonyl cyanide m-chlorophenylhydrazone; Chloroplast; Chloroplasts - drug effects; Chloroplasts - metabolism; Cytochrome b Group - metabolism; DBMIB, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone; DCMU, 3-(3,4-dichlorophenyl)-1,1-dimethylurea; Dibromothymoquinone - pharmacology; Diuron - pharmacology; DNP-INT, 2-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenyl ether; Electron transport; Electron Transport - drug effects; Fabaceae; FeCy, potassium ferricyanide; Ferricyanides - metabolism; HQNO, 2-n-heptyl-4-hydroxyquinoline N-oxide; Hydroxyquinolines - pharmacology; Light-Harvesting Protein Complexes; Molybdenum - metabolism; Oxidation-Reduction; P680, the reaction center of photosystem II; Pheo, the intermediate electron acceptor of photosystem II (pheophytin a); Photosynthetic Reaction Center Complex Proteins - metabolism; Photosystem II; Photosystem II Protein Complex; Plants, Medicinal; Qa and qb, primary and secondary plastoquinones of photosystem II; Qc and Qz, plastoquinone binding sites in the cytochrome blf complex; Qp, membrane pool of plastoquinone; Silicon - metabolism; Silicon Compounds; SiMo, sodium silicomolybdate; Tetramethylphenylenediamine - metabolism; TMPD, N,N,N',N'-tetiamettiyl-p-pheaylenediamme; Trinitrobenzenes - pharmacology; Yz, tyrosine-161 of the photosystem II Dl polypeptide
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(93)80074-5

We show that CCCP, known as an uncoupler of photophosphorylation and an ADRY agent, inhibits FeCy photoreduction and coupled O 2 evolution by isolated chloroplasts equally (1 50 ∼ 2μM), but is practically without effect on the O 2 evolution coupled with SiMo reduction within the 0.2–10μM concentration range. CCCP has no effect on the nanosecond chlorophyll fluorescence in chloroplasts incubated at low light intensity, but decreases it at high light intensity. The electron transfer from reduced TMPD or duroquinol to methylviologen is resistant to CCCP. The efficiency of the CCCP inhibitory action on the FeCy photoreduction depends on the rate of electron flow, which is controlled by the light intensity. The data obtained show that CCCP is oxidized by the photosystem II donor side and is reduced by Q p, competing for electrons with FeCy and the cytochrome blf complex.