Activation by autophosphorylation or cGMP binding produces a similar apparent conformational change in cGMP-dependent protein kinase.
Binding of cyclic nucleotide to or autophosphorylation of cGMP-dependent protein kinase (PKG) activates this kinase, but the molecular mechanism of activation for either process is unknown. Activation of PKG by cGMP binding produces a conformational change in the enzyme (Chu, D.-M., Corbin, J. D., Grimes, K. A., and Francis, S. H. (1997) J. Biol. Chem. 272, 31922-31928; Zhao, J., Trewhella, J., Corbin, J., Francis, S., Mitchell, R., Brushia, R., and Walsh, D. (1997) J. Biol. Chem. 272, 39129-31936). In the present studies, activation of type Ibeta PKG by either autophosphorylation or cGMP-binding alone causes (i) an electronegative charge shift on ion exchange chromatography, (ii) a similar increase ( approximately 3.5 A) in the Stokes radius as determined by gel filtration chromatography, and (iii) a similar decrease in the mobility of the enzyme on native gel electrophoresis. Consistent with these results, cGMP binding increases the rate of phosphoprotein phosphatase-1 catalyzed dephosphorylation of PKG which is autophosphorylated only at Ser-63 (not activated); however, dephosphorylation of PKG that is highly autophosphorylated (activated) is not stimulated by cGMP. The combined results suggest that activation of PKG by either autophosphorylation or cGMP binding alone produces a similar apparent elongation of the enzyme, implying that either process activates the enzyme by a similar molecular mechanism.
Chu
D M
DM
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA.
Francis
S H
SH
Thomas
J W
JW
Maksymovitch
E A
EA
Fosler
M
M
Corbin
J D
JD
D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000502:physiology; D008970:Molecular Weight; D009131:Muscle, Smooth, Vascular / Q000201:enzymology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding / Q000502:physiology; D011487:Protein Conformation; D054645:Protein Phosphatase 1; D014461:Ultracentrifugation
D000242:Cyclic AMP; D017869:Cyclic GMP-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D006152:Cyclic GMP