Regulation of galactokinase gene expression in Tetrahymena thermophila. II. Identification of 3,4-dihydroxyphenylalanine as a primary effector of adrenergic control of galactokinase expression.
Intracellular concentrations of catecholamines were determined in wild-type and mutant Tetrahymena thermophila, using the highly sensitive techniques of high-performance liquid chromatography and electro-chemical detection. Catecholamines were determined in these cell strains grown under various steady-state conditions, including those which initiate and maintain repression of galactokinase gene expression. Wild-type cells grown in defined minimal medium supplemented with 1% glycerol, exhibiting derepressed galactokinase synthesis, were found to contain considerable quantities of dopa (3,4-dihydroxyphenylalanine) and dopamine, but no detectable levels of either norepinephrine or epinephrine. Analyses of wild-type cells revealed a strong positive correlation between the internal concentration of dopa and expression of the galactokinase gene, both of which are regulated by exogenous carbohydrates, catecholamine agonists, or dibutyryl-cAMP; an analogous relationship between intracellular dopamine concentrations and galactokinase activity was not found. In addition, a correlation between intracellular dopa content and the phenotypic expression of galactokinase in various mutants deficient in the catecholamine biosynthetic pathway or in glucokinase further confirms the role of dopa as a primary effector in the regulation of galactokinase gene expression.
Ness
J C
JC
Morse
D E
DE
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D004295:Dihydroxyphenylalanine / Q000378:metabolism / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism; D005686:Galactokinase / Q000235:genetics*; D005690:Galactose / Q000494:pharmacology; D005796:Genes; D005947:Glucose / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D009154:Mutation; D013045:Species Specificity; D013768:Tetrahymena / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D014439:Tyramine / Q000494:pharmacology; D014443:Tyrosine / Q000494:pharmacology
D014443:Tyrosine; D004295:Dihydroxyphenylalanine; D003994:Bucladesine; D005686:Galactokinase; D005947:Glucose; D007545:Isoproterenol; D004298:Dopamine; D005690:Galactose; D014439:Tyramine