Association of the chloroplastic respiratory and photosynthetic electron transport chains of Chlamydomonas reinhardii with photoreduction and the oxyhydrogen reaction

Journal Article · Sat Feb 01 04:00:00 EST 1986 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.80.2.364· OSTI ID:5742480

Maione, T E; Gibbs, M

The hydrogenase-dependent processes, photoreduction and the dark oxyhydrogen reaction, both of which can support CO/sub 2/ assimilation, were compared with aerobic photosynthesis and respiration for their sensitivity to electron transport inhibitors in cells and intact chloroplasts of Chlamydomonas reinhardii 11-32/6. Photoreduction but no photosynthesis was inhibited in chloroplasts and the oxyhydrogen reaction detected only in cells was inhibited up to 75 and 90%, respectively, by 150 micromolar rotenone, indicating the involvement of a NAD(P)H-plastoquinone oxidoreductase in the hydrogen utilizing pathways. The oxyhydrogen reaction coupled to CO/sub 2/ fixation was inhibited more than 95% by 10 micromolar 2,5 - dibromo - 3 - methyl - 6 - isopropyl - p - benzoquinone (DBMIB), a concentration which did not affect respiratory activity. In cells, both photoreduction and the oxyhydrogen reaction exhibited a similar sensitivity to salicylhydroxamic acid (SHAM) showing approximately 90% inhibition by 7 millimolar concentration. Photosynthesis was inhibited only 30% by the same concentration of SHAM. Antimycin A (18 micromolar, 10 micrograms per milliliter) inhibited both photoreduction (80%) and the oxyhydrogen reaction (92%) in cells with the oxyhydrogen reaction being approximately 10 times more sensitive to lower concentrations of the inhibitor. Antimycin A at 18 micromolar concentration did not inhibit photosynthetic CO/sub 2/ fixation unless the cells were adapted to an atmosphere of N/sub 2/ and the reaction conducted anaerobically. Photosynthesis, photoreduction, and the oxyhydrogen reaction coupled to CO/sub 2/ fixation were all inhibited greater than 90% by 10 micromolar carbonylcyanide-p-trifluoromethoxyphenylhydrazone. ATP added to chloroplasts adapted to an atmosphere of H/sub 2/ could support CO/sub 2/ uptake in the dark.

• Research Organization: Brandeis Univ., Waltham, MA
• DOE Contract Number: AC02-76ER03231
• OSTI ID: 5742480
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 80:2; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550500* -- Metabolism
560303 -- Chemicals Metabolism & Toxicology-- Plants-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALGAE
AMINES
ANAEROBIC CONDITIONS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTIMYCIN
AROMATICS
ATP
BENZOQUINONES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL ADAPTATION
BIOLOGICAL PATHWAYS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON DIOXIDE FIXATION
CARBON OXIDES
CELL CONSTITUENTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHLAMYDOMONAS
CHLOROPLASTS
DATA
DRUGS
ELECTRON TRANSFER
ELEMENTS
ENZYMES
EXPERIMENTAL DATA
HYDRAZONES
HYDROGEN
HYDROGENASES
HYDROXAMIC ACIDS
HYDROXY COMPOUNDS
INFORMATION
INHIBITION
KINETICS
MICROORGANISMS
NITROGEN
NONMETALS
NUCLEOTIDE DEHYDROGENASES
NUCLEOTIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDES
OXIDOREDUCTASES
OXYGEN
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANT CELLS
PLANTS
PLASTOQUINONE
QUINONES
REACTION KINETICS
RESPIRATION
SENSITIVITY
SYNTHESIS
UNICELLULAR ALGAE
UPTAKE