title: Conformation changes, N-terminal involvement, and cGMP signal relay in the phosphodiesterase-5 GAF domain.
abstract: The activity of phosphodiesterase-5 (PDE5) is specific for cGMP and is regulated by cGMP binding to GAF-A in its regulatory domain. To better understand the regulatory mechanism, x-ray crystallographic and biochemical studies were performed on constructs of human PDE5A1 containing the N-terminal phosphorylation segment, GAF-A, and GAF-B. Superposition of this unliganded GAF-A with the previously reported NMR structure of cGMP-bound PDE5 revealed dramatic conformational differences and suggested that helix H4 and strand B3 probably serve as two lids to gate the cGMP-binding pocket in GAF-A. The structure also identified an interfacial region among GAF-A, GAF-B, and the N-terminal loop, which may serve as a relay of the cGMP signal from GAF-A to GAF-B. N-terminal loop 98-147 was physically associated with GAF-B domains of the dimer. Biochemical analyses showed an inhibitory effect of this loop on cGMP binding and its involvement in the cGMP-induced conformation changes.
authors.affiliation: Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7260, USA.
authors.forename: Huanchen
authors.initials: H
authors.lastname: Wang
authors.forename: Howard
authors.initials: H
authors.lastname: Robinson
authors.forename: Hengming
authors.initials: H
authors.lastname: Ke
mesh_terms: D006152:Cyclic GMP / Q000737:chemistry* / Q000378:metabolism; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation / Q000502:physiology; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000502:physiology*; D013329:Structure-Activity Relationship
chemical_list: D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human; D006152:Cyclic GMP