Binding of cyclic nucleotides to phosphodiesterase 10A and 11A GAF domains does not stimulate catalytic activity

Karina Matthiesen , Jacob Nielsen (1)

1 Molecular Neurobiology

To date, 11 human cyclic nucleotide phosphodiesterase (PDE) families have been identified. Of these, five families contain non-catalytic tandem GAF domains (GAFa and GAFb) in the N-terminal part of the enzyme. For PDE2A, PDE5A and PDE6, the GAF domains have been shown to bind cyclic GMP with high affinity. For PDE2A and PDE5A, the ligand binding has been shown to stimulate the catalytic activity of the enzyme. For the most recently described PDEs, PDE10A and PDE11A, the GAF domains have previously been suggested to bind cAMP and cGMP, respectively. We have developed scintillation proximity based assays for cyclic nucleotide binding to PDE2A, PDE10A and PDE11A GAF domains. We directly demonstrate binding of cyclic nucleotides to the PDE10A and PDE11A GAF domains and show that these non-catalytic sites bind cAMP and cGMP, respectively, with much higher affinity than has previously been suggested from indirect assessment of the interaction with cyclic nucleotides. The GAFb domain of PDE10A binds cAMP with a KD of 48nM. For PDE11A, the GAFa domain binds cGMP with a KD of 110nM. The effect of binding of ligand to the GAF domains on enzyme activity was investigated through the use of modified cyclic nucleotides. In contrast to the other GAF domain containing PDEs and to what has previously been predicted, ligand binding to the GAF domains of PDE10A and PDE11A does not stimulate catalytic activity.

Mots clés: Life Sciences

Karina Matthiesen, Jacob Nielsen. Binding of cyclic nucleotides to phosphodiesterase 10A and 11A GAF domains does not stimulate catalytic activity. Biochemical Journal, 2009, 423 (3), pp.401-409. ⟨10.1042/BJ20090982⟩. ⟨hal-00479215⟩