Possible Stimulation of Retinal Rod Recovery to Dark State by cGMP Release from a cGMP Phosphodiesterase Noncatalytic Site

Yamazaki, Akio; Бондаренко, В. А.; Dua, Salil; Yamazaki, Matsuyo; Usukura, Jiro; Hayashi, Fumio

doi:10.1074/jbc.271.51.32495

Cited by 37 publications

(57 citation statements)

References 19 publications

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“…Recent evidence has supported the idea that binding of cGMP to noncatalytic sites on amphibian rod PDE enhances the affinity of the inhibitory ␥ subunits for binding to the catalytic subunits (10). Conversely, displacement or removal of the ␥ subunits from PDE by G-protein activation causes a marked decrease in the binding affinity of cGMP with these binding sites (11,12). These results suggest that the noncatalytic cGMP binding sites may be the locus for an additional type of regulation of PDE during visual transduction.…”

mentioning

confidence: 69%

“…Since PDE which lacks P␥ subunits cannot bind 2 B. Jastorff, unpublished results. cGMP at detectable levels (11,12), we infer that Ն90% of the PDE molecules must have bound P␥ subunits. 2) Measurements of the PDE hydrolytic activity of frog ROS homogenates (12 nM PDE) show Ͻ3% of the activity of fully activated PDE (induced by either transducin activation or limited trypsin proteolysis of the P␥ subunit).…”

Section: Methodsmentioning

confidence: 99%

“…For the case of three comparisons of short versus longer chain length substituents at the C-2 position (24 versus 15, 17 versus 11, and 20 versus 16), the longer alkyl group demonstrated a statistically significant higher binding affinity than the shorter alkyl chain. The moderate binding of N 2 -phenyl-cGMP (12), N 2 -biphenyl-cGMP (13), and N 2 -benzyl-cGMP (18) demonstrates that overall bulkiness is not the limiting factor for tight binding at the C-2 position; these three compounds are bulky but still retain their capacity for H bonding. The fact that methyl, ethyl, phenyl, biphenyl, and hexyl substituents at position 2 all bound with moderate affinity indicates that this region of the binding pocket is not spatially constrained, at least in one of the directions occupied by the two N 2 hydrogen atoms in the cGMP molecule.…”

Section: Table II Substitutions In the C-2/n-3 Region Of The Purine Ringmentioning

confidence: 99%

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Structural Features of the Noncatalytic cGMP Binding Sites of Frog Photoreceptor Phosphodiesterase Using cGMP Analogs

Hebert¹,

Schwede²,

Jastorff³

et al. 1998

Journal of Biological Chemistry

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The cGMP-specific phosphodiesterase (PDE) of retinal photoreceptors is a central regulatory enzyme in the visual transduction pathway of vertebrate vision. Although the mechanism of activation of PDE by transducin is well understood, the role of the noncatalytic cGMP binding sites located on the catalytic subunits of PDE remains obscure. We report here for the first time the molecular basis of the noncovalent interactions between cGMP and the high affinity, noncatalytic cGMP binding sites of frog photoreceptor PDE.None of the tested cGMP analogs were able to bind with greater affinity than cGMP itself, and the noncatalytic sites were unable to bind cAMP. The major determinant for discrimination of cGMP over cAMP is in the N-1/C-6 region of the purine ring of cGMP where hydrogen bonding probably stabilizes the selective binding of cGMP. Substitutions at the C-2 position demonstrate that this region of the molecule plays a secondary but significant role in stabilizing cGMP binding to PDE through hydrogen bond interactions. The unaltered hydrogen at the C-8 position is also important for high affinity binding. A significant interaction between the binding pocket and the ribose ring of cGMP occurs at the 2-hydroxyl position. Steric constraints were greatest in the C-8 and possibly the C-6/N-1 regions, whereas the C-2/N-3 and C-2 regions tolerated bulky substituents better. Several lines of evidence indicate that the noncatalytic site binds cGMP in the anti-conformation. The numerous noncovalent interactions between cGMP and the noncatalytic binding pocket of the photoreceptor PDE described in this study account for both the high affinity for cGMP and the high level of discrimination of cGMP from other cyclic nucleotides at the noncatalytic site.Visual excitation of vertebrate retinal photoreceptors begins with the absorption of light by the visual pigment (opsin) which is followed by activation of a G-protein, transducin. This results in activation of a photoreceptor-specific cGMP phosphodiesterase (PDE).1 Increased cGMP hydrolysis lowers the cytoplasmic cGMP concentration which is believed to cause closure of the cGMP-gated ion channel in the plasma membrane and the generation of an electrical response (for reviews, see Refs. 1-5).The rod photoreceptor PDE holoenzyme is a heterotetramer consisting of two non-identical catalytic subunits (␣ and ␤) and two small subunits (␥) that serve to inhibit catalytic activity. Cone photoreceptors have a highly homologous PDE that consists of two identical catalytic subunits (␣Ј) and two conespecific ␥Ј subunits. In addition to containing the active site for cGMP hydrolysis, the catalytic subunits of rod and cone PDEs also possess noncatalytic cGMP binding sites (6). Two other classes of PDEs, namely the cGMP-stimulated PDE (PDE2) and the cGMP-specific PDE (PDE5), are also known to contain noncatalytic binding sites for cGMP. In the case of PDE2, binding of cGMP at the noncatalytic site allosterically activates cyclic nucleotide hydrolysis at the active site (7,8). For PDE5, the...

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mentioning

confidence: 69%

Section: Methodsmentioning

confidence: 99%

Section: Table II Substitutions In the C-2/n-3 Region Of The Purine Ringmentioning

confidence: 99%

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Structural Features of the Noncatalytic cGMP Binding Sites of Frog Photoreceptor Phosphodiesterase Using cGMP Analogs

Hebert¹,

Schwede²,

Jastorff³

et al. 1998

Journal of Biological Chemistry

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“…However, in most of the other PDEs cGMP binding to the GAF domains acts as a means for regulation of the enzyme. For example, the phosphorylation state of PDE5 (35,36) and the interaction between the catalytic subunits and the inhibitory ␥-subunits and transducin in PDE6 (33,37) are regulated by cGMP binding. Binding of cGMP to the noncatalytic GAF domain in PDE2 acts as a direct allosteric activator of catalytic activity (38).…”

Section: Discussionmentioning

confidence: 99%

Cloning and characterization of a cAMP-specific phosphodiesterase (TbPDE2B) from Trypanosoma brucei

Rascón

Soderling

Schaefer

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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Here we report the cloning, expression, and characterization of a cAMP-specific phosphodiesterase (PDE) from Trypanosoma brucei (TbPDE2B). Using a bioinformatic approach, two different expressed sequence tag clones were identified and used to isolate the complete sequence of two identical PDE genes arranged in tandem. Each gene consists of 2,793 bases that predict a protein of 930 aa with a molecular mass of 103.2 kDa. Two GAF (for cGMP binding and stimulated PDEs, Anabaena adenylyl cyclases, and Escherichia coli FhlA) domains, similar to those contained in many signaling molecules including mammalian PDE2, PDE5, PDE6, PDE10, and PDE11, were located N-terminal to a consensus PDE catalytic domain. The catalytic domain is homologous to the catalytic domain of all 11 mammalian PDEs, the Dictyostelium discoideum RegA, and a probable PDE from Caenorhabditis elegans. It is most similar to the T. brucei PDE2A (89% identity). TbPDE2B has substrate specificity for cAMP with a K m of 2.4 M. cGMP is not hydrolyzed by TbPDE2B nor does this cyclic nucleotide modulate cAMP PDE activity. The nonselective PDE inhibitors 3-isobutyl-1-methylxanthine, papaverine and pentoxifyline are poor inhibitors of TbPDE2B. Similarly, PDE inhibitors selective for the mammalian PDE families 2, 3, 5, and 6 (erythro-9-[3-(2-hydroxynonyl)]-adenine, enoximone, zaprinast, and sildenafil) were also unable to inhibit this enzyme. However, dipyridamole was a reasonably good inhibitor of this enzyme with an IC50 of 27 M. cAMP plays key roles in cell growth and differentiation in this parasite, and PDEs are responsible for the hydrolysis of this important second messenger. Therefore, parasite PDEs, including this one, have the potential to be attractive targets for selective drug design.inhibitors ͉ GAF domain

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“…In PDE5 cGMP binding is proposed to modulate enzyme activation by means of phosphorylation of the enzyme (31,32). The analogous site in PDE2 functions as an allosteric activator of cAMP and probably cGMP hydrolysis (33), whereas in PDE6 cGMP binding is thought to regulate the interaction between the catalytic and inhibitory ␥-subunits and transducin (34,35). In PDE11A1 the homologous domain has a deletion as compared with PDE5 that coincides with the respective tandem NKX n D motifs such that the result is a single putative cGMP-binding NKX n D motif (amino acids 88-99, Fig.…”

Section: Discussionmentioning

confidence: 99%

Molecular cloning and characterization of a distinct human phosphodiesterase gene family: PDE11A

Fawcett¹

2000

Proceedings of the National Academy of Sciences

173

140

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We report here the cloning, expression, and characterization of human PDE11A1, a member of a distinct cyclic nucleotide phosphodiesterase (PDE) family. PDE11A exhibits <50% amino acid identity with the catalytic domains of all other PDEs, being most similar to PDE5, and has distinct biochemical properties. The human PDE11A1 cDNA isolated contains a complete open reading frame encoding a 490-amino acid enzyme with a predicted molecular mass of 55,786 Da. At the N terminus PDE11A1 has a single GAF domain homologous to that found in other signaling molecules, including PDE2, PDE5, PDE6, and PDE10, which constitutes a potential allosteric binding site for cGMP or another small ligand. Tissue distribution studies indicate that PDE11A mRNA occurs at highest levels in skeletal muscle, prostate, kidney, liver, pituitary, and salivary glands and testis. PDE11A is expressed as at least three major transcripts of Ϸ10.5, Ϸ8.5, and Ϸ6.0 kb, thus suggesting the existence of multiple subtypes. This possibility is further supported by the detection of three distinct proteins of Ϸ78, Ϸ65, and Ϸ56 kDa by Western blotting of human tissues for PDE11A isoforms. Recombinant human PDE11A1 hydrolyzes both cGMP and cAMP with K m values of 0.52 M and 1.04 M, respectively, and similar V max values. Therefore, PDE11A represents a dual-substrate PDE that may regulate both cGMP and cAMP under physiological conditions. PDE11A is sensitive to the nonselective PDE inhibitor 3-isobutyl-1-methylxanthine (IBMX) as well as zaprinast and dipyridamole, inhibitors that are generally considered relatively specific for the cGMP-selective PDEs, with IC50 values of 49.8 M, 12.0 M, and 0.37 M, respectively.

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Possible Stimulation of Retinal Rod Recovery to Dark State by cGMP Release from a cGMP Phosphodiesterase Noncatalytic Site

Cited by 37 publications

References 19 publications

Structural Features of the Noncatalytic cGMP Binding Sites of Frog Photoreceptor Phosphodiesterase Using cGMP Analogs

Structural Features of the Noncatalytic cGMP Binding Sites of Frog Photoreceptor Phosphodiesterase Using cGMP Analogs

Cloning and characterization of a cAMP-specific phosphodiesterase (TbPDE2B) from Trypanosoma brucei

Molecular cloning and characterization of a distinct human phosphodiesterase gene family: PDE11A

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