The regulatory tandem domains of human phosphodiesterases 1 and 4 regulate a cyanobacterial adenylyl cyclase

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• 作者：Ana Banjac ; Ursula Kurz ; Joachim E. Schultz ; ^{joachim.schultz@uni-tuebingen.de}
• 关键词：hPDE ; human phosphodiesterase ; CyaB1 AC ; cyanobacterial adenylyl cyclase from Anabaena sp. ; PKA ; cAMP-dependent protein kinase
• 刊名：Cellular Signalling
• 出版年：2012
• 期刊代码：42_08986568
• 类别：bio
• 出版时间：August, 2012
• 卷：24
• 期：8
• 页码：1479-1484
• 文件大小：1000 K

摘要

Human phosphodiesterase 1 is regulated by a tandem of N-terminal calmodulin/Ca²⁺-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 Ca²⁺/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.