Zinc dependent activation of cAMP-specific phosphodiesterase (PDE4A)

Biochem Biophys Res Commun. 1997 Dec 8;241(1):175-80. doi: 10.1006/bbrc.1997.7542.

Abstract

Cyclic nucleotide phosphodiesterases (PDE), including PDE4A, contain two consensus sequences (HX3HX24-26E) which have been associated with Zn2+ binding and activation with other proteins. This study shows that Zn2+ activates purified recombinant human PDE4A with an EC50 of <1 microM. The EC50 for Mg2+, the generally accepted activating metal ion, is approximately 100 microM. Zn2+ concentrations higher than 5 microM are inhibitory. Mn2+, Co2+ and Ni2+ also activate PDE4A with EC50 values of approximately 2, 3 and 10 microM, respectively. PDE4A binds 65Zn2+ with a Kd of 0.4 microM and approximately 1:1 stoichiometry. Titrations of PDE4A inhibition with Mg2+ and Zn2+ as activating metal ions showed that the competitive inhibitors R-Rolipram, CDP-840, RS-14203 and KF18280 are shifted at least 10-fold to lower potency in the presence of Zn2+. The effect is likely at the site of inhibitor binding as the Km for cAMP in the presence of Mg2+ and Zn2+ is similar (1-3 microM). The Kd of [3H]-R-Rolipram for PDE4A was increased at least 30-fold from 3 nM (with Mg2+) by the presence of Zn2+. The high affinity of Zn2+ for PDE4A indicates that this metal may play a role in the regulation of PDE4A activity.

MeSH terms

  • 3',5'-Cyclic-AMP Phosphodiesterases / isolation & purification
  • 3',5'-Cyclic-AMP Phosphodiesterases / metabolism*
  • Cations, Divalent / pharmacology
  • Chromatography, Gel
  • Chromatography, Ion Exchange
  • Enzyme Activation
  • Humans
  • Kinetics
  • Magnesium / pharmacology
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Zinc / metabolism
  • Zinc / pharmacology*

Substances

  • Cations, Divalent
  • Recombinant Proteins
  • 3',5'-Cyclic-AMP Phosphodiesterases
  • Magnesium
  • Zinc