Transient inactivation of the thylakoid photosystem II light-harvesting protein kinase system and concomitant changes in intramembrane particle size during photoinhibition of Chlamydomonas reinhardtii

Journal Article · Tue Jul 01 04:00:00 EDT 1986 · J. Cell Biol.; (United States)

DOI:https://doi.org/10.1083/jcb.103.1.71· OSTI ID:5125818

Schuster, G; Dewit, M; Staehelin, L A; Ohad, I

Light-dependent reduction of the plastoquinone pool regulates the activity of the thylakoid-bound protein kinase which phosphorylates the light harvesting chlorophyll a,b-protein complex (LHC II) and regulates energy distribution between photosystems II (PS II) and I. Since reduction of plastoquinone by PS II is abolished in photoinhibited thylakoids due to loss of the secondary electron acceptor QB protein, it was of interest to examine the activity of the LHC II protein kinase system during photoinhibition and recovery of PS II activity. The kinase activity was assessed both in vivo and in vitro in Chlamydomonas cells exposed to high light intensity (photoinhibition) and recovery at low light intensity. The kinase activity was progressively reduced during photoinhibition and became undetectable after 90 min. The inactive LHC II-kinase system could not be reactivated in vitro either by light or by reduction of the plastoquinone pool following addition of reduced duroquinone (TMQH2). The LHC II polypeptides were dephosphorylated in vivo when cells, prelabeled with (32P)orthophosphate before exposure to high light intensity, were transferred to photoinhibiting light in the presence of (32P)orthophosphate. In vivo recovery of the LHC II-kinase activity, elicited by the addition of TMQH2 to the assay system, did not require restoration of QB-dependent electron flow or de novo protein synthesis, either in the cytoplasm or in the chloroplast. Mild sonication of thylakoids isolated from photoinhibited cells restored the ability of the LHC II protein kinase system to be activated in vitro by addition to TMQH2. Restoration of the light-activated LHC-II kinase required recovery of QB-dependent electron flow. At the structural level, photoinhibition did not affect the ratio of grana/stroma thylakoids.

• OSTI ID: 5125818
• Journal Information: J. Cell Biol.; (United States), Journal Name: J. Cell Biol.; (United States) Vol. 1; ISSN JCLBA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALGAE
AROMATICS
BENZOQUINONES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
CHLAMYDOMONAS
CHLOROPHYLL
CHLOROPLASTS
DAYS LIVING RADIOISOTOPES
ELECTRON TRANSFER
ENZYMES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INACTIVATION
INHIBITION
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MICROORGANISMS
MOLECULAR WEIGHT
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYTOCHROMES
PIGMENTS
PLANTS
PLASTOQUINONE
PORPHYRINS
PROTEINS
QUINONES
RADIOISOTOPES
SYNTHESIS
TRACER TECHNIQUES
TRANSFERASES
UNICELLULAR ALGAE