Biomaterial Database

Elicitor modulation of the turnover of L-phenylalanine ammonia-lyase in French bean cell suspension cultures. 1980

M A Lawton, and R A Dixon, and C J Lamb

(1) The mechanisms underlying the transient increase in phenylalanine ammonia-lyase activity during phaseollin accumulation in cell suspension cultures of Dwarf French bean (Phaseolus volgaris) have been investigated using density labelling with 3H from 2H2O coupled with residual analysis of the equilibrium distribution of enzyme activity in high-resolution KBr density gradients. (2) The resolution achieved in this system is sufficient to allow quantitative analysis of the relative proportions of light, unlabelled, pre-existing enzyme and heavy, labelled, newly synthesised enzyme. (3) Elicitor released by heat treatment of cell walls of Colletotrichum lindemuthianum, the causal agent of anthracnose disease of French bean, caused a marked but transient increase in phenylalanine ammonia-lyase activity concomitant with the onset of phaseollin accumulation in the bean cultures. The induction of enzyme activity was highly dependent on elicitor concentration, with maximum induction occurring in two discrete concentration ranges; at an intermediate elicitor concentration, or at supra-optimal elicitor concentrations, no enzyme induction was observed. (4) At low concentrations of elicitor the induction of enzyme was entirely a result of elicitor stimulation of the rate of de novo enzyme production. In contrast, at higher elicitor concentrations the increase in enzyme activity was accompanied by a marked apparent stabilization of the enzyme in vivo, and the rapid but transient increase in enzyme activity was achieved by a programme of reciprocal changes in the rate constant for de novo enzyme production and the rate constant for removal of enzyme activity. Such reciprocal control of the rates of enzyme production and removal may be crucial in determining the magnitude and duration of the phytoalexin defense response. (5) Information on the specific activity of 2H label in the amino acid pools was obtained from analysis of the equilibrium distribution of residual, labelled activity. This showed directly that the turnover of the amino acid pools was fast relative to the turnover of phenylalanine ammonia-lyase and, hence, the rate of enzyme labelling was not limited by the rate of labelling of the amino acid pools. Elicitor treatment had no effect on the specific activity of label in the amino acid pools from which phenylalanine ammonia-lyase is synthesised.

UI	MeSH Term	Description	Entries
D010650	Phenylalanine Ammonia-Lyase	An enzyme that catalyzes the deamination of PHENYLALANINE to form trans-cinnamate and ammonia.	Phenylalanine-Tyrosine Ammonia-lyase,Ammonia-Lyase, Phenylalanine,Ammonia-lyase, Phenylalanine-Tyrosine,Phenylalanine Ammonia Lyase,Phenylalanine Tyrosine Ammonia lyase
D010944	Plants	Multicellular, eukaryotic life forms of kingdom Plantae. Plants acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations. It is a non-taxonomical term most often referring to LAND PLANTS. In broad sense it includes RHODOPHYTA and GLAUCOPHYTA along with VIRIDIPLANTAE.	Plant
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D002499	Centrifugation, Density Gradient	Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Centrifugations, Density Gradient,Density Gradient Centrifugation,Density Gradient Centrifugations,Gradient Centrifugation, Density,Gradient Centrifugations, Density
D003904	Mitosporic Fungi	A large and heterogenous group of fungi whose common characteristic is the absence of a sexual state. Many of the pathogenic fungi in humans belong to this group.	Deuteromycetes,Deuteromycota,Fungi imperfecti,Fungi, Mitosporic,Hyphomycetes,Deuteromycete,Deuteromycotas,Fungi imperfectus,Fungus, Mitosporic,Hyphomycete,Mitosporic Fungus,imperfectus, Fungi
D004790	Enzyme Induction	An increase in the rate of synthesis of an enzyme due to the presence of an inducer which acts to derepress the gene responsible for enzyme synthesis.	Induction, Enzyme
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D000642	Ammonia-Lyases	Enzymes that catalyze the formation of a carbon-carbon double bond by the elimination of AMMONIA. EC 4.3.1.	Ammonia Lyase,Ammonia-Lyase,Ammonia Lyases,Lyase, Ammonia