N-Terminal domain of phosphodiesterase-11A4 (PDE11A4) decreases affinity of the catalytic site for substrates and tadalafil, and is involved in oligomerization.
The phosphodiesterase-11A (PDE11) family consists of four splice variants (PDE11A1-PDE11A4) that contain a conserved carboxyl-terminal (C-terminal) catalytic domain that hydrolyzes cAMP and cGMP; the amino-termini (N-termini) vary in length and amino acid sequence. PDE11A2, PDE11A3, and PDE11A4 contain one or more GAF (cGMP-binding phosphodiesterase, Anabaena adenylyl cyclase, and Escherichia coli FhlA) subdomains. In the present study, PDE11A1 and PDE11A2 demonstrated higher affinity for cAMP and cGMP when directly compared to that of the longest isoform, PDE11A4. Moreover, PDE11A3, PDE11A2, and PDE11A1, which contain progressively shorter N-termini, were more sensitive than PDE11A4 to inhibition by two structurally unrelated inhibitors, tadalafil (Cialis) and vardenafil (Levitra). The substrate and inhibitor affinity differences among the PDE11 isozymes could not be ascribed to differences in their quaternary structure since PDE11A4, PDE11A3, and PDE11A2 were determined to be dimers, and PDE11A1 was a tetramer. These data also demonstrate that PDE11 isozymes containing at least 123 C-terminal amino acids of the GAF-B domain are stable oligomers and that GAF-A is not required for oligomerization. The isolated PDE11 catalytic domain (Met-563-Asn-934) displayed both monomeric and dimeric forms, and upon dilution, this domain was primarily monomeric, indicating that the main oligomerization contacts are within the N-termini of PDE isozymes. This report is the first to describe an inhibitory effect of the N-terminal region of PDE11A4 on the affinity of the catalytic domain for both substrates and inhibitors and the first to define the quaternary structure and the regions that contribute to this structure within the human PDE11A family.
Weeks
James L
JL
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, Tennessee 37232-0615, USA.
Zoraghi
Roya
R
Francis
Sharron H
SH
Corbin
Jackie D
JD
D015106:3',5'-Cyclic-GMP Phosphodiesterases; D002243:Carbolines / Q000378:metabolism* / Q000494:pharmacology; D020134:Catalytic Domain; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000378:metabolism / Q000494:pharmacology; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D010879:Piperazines / Q000378:metabolism / Q000494:pharmacology; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D013379:Substrate Specificity / Q000187:drug effects; D013450:Sulfones / Q000378:metabolism / Q000494:pharmacology; D000068581:Tadalafil; D014227:Triazines / Q000378:metabolism / Q000494:pharmacology; D000069058:Vardenafil Dihydrochloride
D002243:Carbolines; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007527:Isoenzymes; D010879:Piperazines; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride; D000068581:Tadalafil; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; C406737:PDE11A protein, human