title: The regulatory tandem domains of human phosphodiesterases 1 and 4 regulate a cyanobacterial adenylyl cyclase.
abstract: Human phosphodiesterase 1 is regulated by a tandem of N-terminal calmodulin/Ca(2+)-binding domains. We grafted the tandems from hPDE1A3 and -B1 onto the cyanobacterial adenylyl cyclase CyaB1 thus replacing an intrinsic tandem GAF-domain. Cyclase activity was stimulated by Ca(2+)/calmodulin 1.9 to 4.4-fold, i.e. similarly as reported for hPDE1 regulation. hPDE4 long isoforms are activated by phosphorylation of a serine located in a conserved RRESF motif in a tandem of N-terminal upstream-conserved regions (UCR). We grafted the UCR tandems from hPDE4A4, -B1, and -D3 onto the CyaB1 cyclase as a reporter enzyme. Activity was enhanced 1.4 to 4.5-fold by respective phosphomimetic (S/D) point mutations. Similarly, cyclase activity was increased 2.5-fold by phosphorylation of the chimera with the PDE4D3 UCR tandem by cAMP-dependent protein kinase. We propose a common mechanism of activation in mammalian phosphodiesterases containing N-terminal tandem regulatory domains. A downstream region is suggested to alternate between random and ordered conformations and to enable switching between inactive, the catalytic domain occluding PDE homodimers and active monomeric PDE catalytic domains.
authors.affiliation: Pharmazeutisches Institut, Universität Tübingen, Tübingen, Germany.
authors.forename: Ana
authors.initials: A
authors.lastname: Banjac
authors.forename: Ursula
authors.initials: U
authors.lastname: Kurz
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Schultz
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D055162:Biocatalysis; D000458:Cyanobacteria / Q000201:enzymology*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000378:metabolism*; D006801:Humans; D043264:Phosphodiesterase I / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary
chemical_list: D043264:Phosphodiesterase I; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D000262:Adenylyl Cyclases