A novel mechanism for adenylyl cyclase inhibition from the crystal structure of its complex with catechol estrogen.
Catechol estrogens are steroid metabolites that elicit physiological responses through binding to a variety of cellular targets. We show here that catechol estrogens directly inhibit soluble adenylyl cyclases and the abundant trans-membrane adenylyl cyclases. Catechol estrogen inhibition is non-competitive with respect to the substrate ATP, and we solved the crystal structure of a catechol estrogen bound to a soluble adenylyl cyclase from Spirulina platensis in complex with a substrate analog. The catechol estrogen is bound to a newly identified, conserved hydrophobic patch near the active center but distinct from the ATP-binding cleft. Inhibitor binding leads to a chelating interaction between the catechol estrogen hydroxyl groups and the catalytic magnesium ion, distorting the active site and trapping the enzyme substrate complex in a non-productive conformation. This novel inhibition mechanism likely applies to other adenylyl cyclase inhibitors, and the identified ligand-binding site has important implications for the development of specific adenylyl cyclase inhibitors.
Steegborn
Clemens
C
Department of Biochemistry, Weill Medical College of Cornell University, New York, New York 10021, USA.
Litvin
Tatiana N
TN
Hess
Kenneth C
KC
Capper
Austin B
AB
Taussig
Ronald
R
Buck
Jochen
J
Levin
Lonny R
LR
Wu
Hao
H
D000255:Adenosine Triphosphate / Q000378:metabolism; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D000458:Cyanobacteria / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000378:metabolism; D002393:Estrogens, Catechol / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D017434:Protein Structure, Tertiary
D000067956:Adenylyl Cyclase Inhibitors; D004791:Enzyme Inhibitors; D002393:Estrogens, Catechol; D000255:Adenosine Triphosphate; D000262:Adenylyl Cyclases