Temperature-sensitive rubisco mutant of Chlamydomonas. [Chlamydomonas reinhardtii]
The Chlamydomonas reinhardtii mutant 68-4PP is a temperature-sensitive mutant that lacks photosynthetic ability at 35/sup 0/C, but is able to grow photosynthetically at 25/sup 0/C. Genetic analysis indicated that 68-4PP is a chloroplast mutant that is allelic with known Rubisco large-subunit structural-gene mutants, implying that 68-4PP also resulted from a mutation in the large-subunit gene. The 68-4PP mutant has about 35% of the wild-type level of Rubisco holoenzyme and carboxylase activity when grown at 25/sup 0/C, but it has less than 10% of normal holoenzyme and carboxylase activity when grown at 35/sup 0/C. However, (/sup 35/S)-sulfate pulse labeling showed that Rubisco subunits were synthesized at normal rates at both temperatures. More significantly, the ratio of carboxylase activity in the absence and presence of oxygen at a limiting CO/sub 2/ concentration (6.6 ..mu..M) was about 2.2 for the mutant enzyme, as compared to about 3.0 for the wild-type enzyme. The decreased ratio of the mutant enzyme is maternally inherited, indicating that this reduced oxygen sensitivity results from a mutation in chloroplast DNA. The authors have recently cloned the 68-4PP Rubisco large-subunit gene, and DNA sequencing is in progress.
- Research Organization:
- Univ. of Nebraska, Lincoln
- OSTI ID:
- 6072989
- Report Number(s):
- CONF-8707108-
- Journal Information:
- Plant Physiol., Suppl.; (United States), Journal Name: Plant Physiol., Suppl.; (United States) Vol. 83:4; ISSN PPYSA
- Country of Publication:
- United States
- Language:
- English
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560200 -- Thermal Effects
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALGAE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBON-CARBON LYASES
CARBOXY-LYASES
CELL CONSTITUENTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHLAMYDOMONAS
CHLOROPLASTS
DAYS LIVING RADIOISOTOPES
DNA
ELEMENTS
ENZYME ACTIVITY
ENZYMES
EVEN-ODD NUCLEI
GENETIC MAPPING
GENOME MUTATIONS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIGHT NUCLEI
LYASES
MAPPING
MICROORGANISMS
MUTANTS
MUTATIONS
NONMETALS
NUCLEI
NUCLEIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANTS
RADIOISOTOPES
REACTION KINETICS
RIBULOSE DIPHOSPHATE CARBOXYLASE
SULFUR 35
SULFUR ISOTOPES
SYNTHESIS
TEMPERATURE EFFECTS
TRACER TECHNIQUES
UNICELLULAR ALGAE