Zinc inhibition of adenylyl cyclase correlates with conformational changes in the enzyme.
We have previously demonstrated that Zn(2+) inhibits hormone and forskolin stimulation of cAMP synthesis in intact N18TG2 cells, corresponding plasma membranes, and of recombinant adenylyl cyclase isoforms. If, however, the enzyme is pre-activated by hormone or forskolin, Zn(2+) inhibition is attenuated [J. Biol. Chem. 277 (2002) 11859]. We have extended our analyses of this inhibition to investigations of soluble adenylyl cyclase, composed of the CI and CII domains of the full-length protein. The properties of Zn(2+) inhibition of the soluble enzyme parallel that of the full-length protein, including the fact that inhibition is not competitive with Mg(2+). By monitoring intrinsic and extrinsic fluorescence, we demonstrate changes in enzyme conformers in response to the addition of varied effectors. The data suggest a possible mechanism by which Zn(2+) inhibits adenylyl cyclase activity.
Klein
Claudette
C
Department of Biochemistry and Molecular Biology, Saint Louis University, School of Medicine, 1402 S. Grand Boulevard, St. Louis, MO 63104, USA. kleinc@slu.edu
Heyduk
Tomasz
T
Sunahara
Roger K
RK
D000262:Adenylyl Cyclases / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry*; D008968:Molecular Conformation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
D011994:Recombinant Proteins; D000262:Adenylyl Cyclases; D008274:Magnesium; D015032:Zinc