The role of tryptophan 1072 in human PDE3B inhibitor binding.
The catalytic domain of recombinant human PDE3B was expressed in Escherichia coli as inclusion bodies and refolded to form active enzyme. A mutation at tryptophan 1072 in PDE3B disrupts inhibitor binding, but has minimal effect on cAMP hydrolysis. The W1072A mutation caused a 158-fold decrease in affinity for cilostamide, a 740-fold decrease for cGMP, and a 15-fold decrease in affinity for IBMX. The corresponding tyrosine mutation had a smaller effect. However, the K(m) of cAMP for the W1072A mutation was only increased by about 7-fold. The data indicate that the inhibitor binding region is not completely coincident with the substrate binding region. The homologous residue in PDE4B is located on helix 16 within 7A of the predicted bound substrate. A model of PDE3B was constructed based on the X-ray crystal structure of PDE4B.
Chung
Christine
C
Department of Metabolic Disorders, Merck Research Laboratories, P.O. Box 2000, Mailstop: RY80M-213, Rahway, NJ 07065, USA.
Varnerin
Jeffrey P
JP
Morin
Nancy R
NR
MacNeil
Douglas J
DJ
Singh
Suresh B
SB
Patel
Sangita
S
Scapin
Giovanna
G
Van der Ploeg
Lex H T
LH
Tota
Michael R
MR
D015056:1-Methyl-3-isobutylxanthine / Q000378:metabolism / Q000494:pharmacology; D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D020134:Catalytic Domain; D006152:Cyclic GMP / Q000378:metabolism / Q000494:pharmacology; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010726:Phosphodiesterase Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D015363:Quinolones / Q000378:metabolism / Q000494:pharmacology; D016415:Sequence Alignment; D014364:Tryptophan / Q000235:genetics / Q000502:physiology*
D010726:Phosphodiesterase Inhibitors; D015363:Quinolones; C021294:cilostamide; D014364:Tryptophan; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517291:PDE3B protein, human; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine