Expression of chloroplast protein genes during the cell cycle of Chlamydomonas reinhardtii: evidence for transcriptional and translocational control
Chlamydomonas reinhardtii cells, growing synchronously under a repeating 12 h light:12 h dark cycle, were used to investigate the synthesis and regulation of chloroplast proteins. The cells accumulate chlorophyll, the major thylakoid membrane proteins, and ribulose-1,5-bisphosphate carboxylase (RuBPCase) during the light (G1) period of the cell cycle. Pulse-labeling in vivo with (/sup 3/H)arginine, and analysis of the protein synthetic capacity of thylakoid-bound polysomes in vitro, shows that these proteins are synthesized de novo during the light. Specific antibody and cloned DNA probes were obtained and used to estimate translatable and/or steady-state mRNA levels for light-harvesting (LHCII) and reaction center (D-1 and D-2) polypeptides of photosystem II, a light-harvesting polypeptide of photosystem I (LHCI), and the large (LS) and small (SS) subunits of RuBPCase. Levels of mRNA for the nuclear-encoded LHCI, LHCII and SS correlated with the synthesis of these polypeptides in vivo; they were higher in the light period and several-folded lower or absent during the dark period. The results suggest that synthesis of nuclear-encoded chloroplast proteins are regulated primarily by the level of mRNA. In contrast, regulation of chloroplast-encoded genes is achieved by controlling the translation of mRNA that is constitutively present, and by transcriptional mechanisms during light induction.
- Research Organization:
- University of South Florida, Tampa (USA)
- OSTI ID:
- 6712707
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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CHLAMYDOMONAS
CELL CYCLE
CHLOROPHYLL
BIOSYNTHESIS
TRITIUM COMPOUNDS
CHLOROPLASTS
GENES
GENETICS
MESSENGER-RNA
PHOTOSYNTHESIS
PROTEINS
TRANSCRIPTION
VISIBLE RADIATION
ALGAE
BIOLOGY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
LABELLED COMPOUNDS
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHYTOCHROMES
PIGMENTS
PLANTS
PORPHYRINS
RADIATIONS
RNA
SYNTHESIS
UNICELLULAR ALGAE
550401* - Genetics- Tracer Techniques