Expression of an active, monomeric catalytic domain of the cGMP-binding cGMP-specific phosphodiesterase (PDE5).
Phosphodiesterases (PDEs) comprise a superfamily of phosphohydrolases that degrade 3',5'-cyclic nucleotides. All known mammalian PDEs are dimeric, but the functional significance of dimerization is unknown. A deletion mutant of cGMP-binding cGMP-specific PDE (PDE5), encoding the 357 carboxyl-terminal amino acids including the catalytic domain, has been generated, expressed, and purified. The K(m) of the catalytic fragment for cGMP (5.5 +/- 0. 51 microM) compares well with those of the native bovine lung PDE5 (5.6 microM) and full-length wild type recombinant PDE5 (2 +/- 0.4 microM). The catalytic fragment and full-length PDE5 have similar IC(50) values for the inhibitors 3-isobutyl-1-methylxanthine (20 microM) and sildenafil (Viagra(TM))(4 nM). Based on measured values for Stokes radius (29 A) and sedimentation coefficient (2.9 S), the PDE5 catalytic fragment has a calculated molecular mass of 35 kDa, which agrees well with that predicted by amino acid content (43.3 kDa) and with that estimated using SDS-polyacrylamide gel electrophoresis (39 kDa). The combined data indicate that the recombinant PDE5 catalytic fragment is monomeric, and retains the essential catalytic features of the dimeric, full-length enzyme. Therefore, the catalytic activity of PDE5 holoenzyme requires neither interaction between the catalytic and regulatory domains nor interactions between subunits of the dimer.
Fink
T L
TL
Department of Molecular Physiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA.
Francis
S H
SH
Beasley
A
A
Grimes
K A
KA
Corbin
J D
JD
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D000818:Animals; D002417:Cattle; D002499:Centrifugation, Density Gradient; D006152:Cyclic GMP / Q000737:chemistry* / Q000235:genetics*; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic; D020128:Inhibitory Concentration 50; D007700:Kinetics; D016350:Leucine Zippers; D016296:Mutagenesis; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D010879:Piperazines / Q000494:pharmacology; D011687:Purines; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D000068677:Sildenafil Citrate; D013450:Sulfones
D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D011994:Recombinant Proteins; D013450:Sulfones; D000068677:Sildenafil Citrate; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine