Different rates of synthesis and degradation of two chloroplastic ammonium-inducible NADP-specific glutamate dehydrogenase isoenzymes during induction and deinduction in Chlorella sorokiniana cells

Journal Article · Thu Jan 01 04:00:00 EST 1987 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.83.1.85· OSTI ID:6528169

Bascomb, N F; Prunkard, D E; Schmidt, R R

The kinetics of accumulation (per milliliter of culture) of the ..cap alpha..- and ..beta..-subunits, associated with chloroplast-localized ammonium inducible nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase (NADP-GDH) isoenzymes, were measured during a 3 hour induction of synchronized daughter cells of Chlorella sorokiniana in 29 millimolar ammonium medium under photoautotrophic conditions. The ..beta..-subunit holoenzyme(s) accumulated in a linear manner for 3 hours without an apparent induction lag. A 40 minute induction lag preceded the accumulation of the ..cap alpha..-subunit holoenzyme(s). After 120 minutes, the ..cap alpha..-subunit ceased accumulating and thereafter remained at a constant level. From pulse-chase experiments, using /sup 35/SO/sub 4/ and immunochemical procedures, the rate of synthesis of the ..cap alpha..-subunit was shown to be greater than the ..beta..-subunit during the first 80 minutes of induction. The ..cap alpha..- and ..beta..-subunits had different rates of degradation during the induction period (t/sub 1/2/ = 50 versus 150 minutes, respectively) and during the deinduction period (t/sub 1/2/ = 5 versus 13.5 minutes) after removal of ammonium from the culture. During deinduction, total NADP-GDH activity decreased with a half-time of 9 minutes. Cycloheximide completely inhibited the synthesis and degradation of both subunits. A model for regulation of expression of the NADP-GDH gene was proposed.

• Research Organization: Univ. of Florida, Gainesville
• OSTI ID: 6528169
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 83:1; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALGAE
AMMONIUM COMPOUNDS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
CELL CULTURES
CHLORELLA
COENZYMES
CYCLOHEXIMIDE
DAYS LIVING RADIOISOTOPES
DRUGS
EVEN-ODD NUCLEI
FUNGICIDES
GENE REGULATION
INHIBITION
ISOENZYMES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MATHEMATICAL MODELS
MICROORGANISMS
NADP
NUCLEI
NUCLEOTIDES
ORGANIC COMPOUNDS
PESTICIDES
PLANTS
RADIOISOTOPES
REACTION KINETICS
SULFUR 35
SULFUR ISOTOPES
SYNTHESIS
TRACER TECHNIQUES
UNICELLULAR ALGAE