Selective activation of calcineurin by dipicolinic acid.
Calcineurin was activated at 30 degrees C by incubation with dipicolinic acid, a metal chelator, in the absence of activating, exogenous Mn2+. The activation reached a plateau after 90 min with 8- to 12-fold higher activity. Inclusion of the activating metal Mn2+ (1.0 mM) in the incubation mixture slightly lessened the activation induced by dipicolinic acid. The chelator 1,10-phenanthroline had no effect on the activity of calcineurin in concurrent experiments. Activation by dipicolinic acid was reversed by the addition of Zn2+ or Fe3+. The reversal occurred within 30 min after the addition of either metal and returned the activity of calcineurin to its initial level. Atomic absorption spectrometry analysis showed no loss of iron or zinc from calcineurin after activation (2 h) by dipicolinic acid. Because there seemed to be no interaction between dipicolinic acid and exogenous metal, the effect of dipicolinic acid was concluded to result from masking of at least one intrinsic metal. Calcineurin incubated with 1.0 mM Mn2+ (saturating levels) also did not show any loss of intrinsic metal by atomic absorption analysis. The consequences of these data concerning the role(s) of intrinsic metals in calcineurin catalysis are discussed.
Martin
B L
BL
Department of Biochemistry, University of Tennessee, Memphis 38163, USA. bmartin@utmem1.utmem.edu
D000818:Animals; D019703:Calcineurin; D002148:Calmodulin-Binding Proteins / Q000187:drug effects*; D002417:Cattle; D002614:Chelating Agents / Q000494:pharmacology*; D002712:Chlorides / Q000494:pharmacology; D004789:Enzyme Activation; D005290:Ferric Compounds / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D010618:Phenanthrolines / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000187:drug effects*; D010848:Picolinic Acids / Q000494:pharmacology*; D013054:Spectrophotometry, Atomic; D017967:Zinc Compounds / Q000494:pharmacology
D002148:Calmodulin-Binding Proteins; D002614:Chelating Agents; D002712:Chlorides; D005290:Ferric Compounds; D010618:Phenanthrolines; D010848:Picolinic Acids; D017967:Zinc Compounds; D008345:Manganese; C016837:zinc chloride; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; C024555:ferric chloride; C004860:dipicolinic acid; C025205:1,10-phenanthroline