1u0h

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spinqualitylabelsall models 1u0h, resolution 2.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURAL BASIS FOR THE INHIBITION OF MAMMALIAN ADENYLYL CYCLASE BY MANT-GTP

Overview

Membrane-bound mammalian adenylyl cyclase (mAC) catalyzes the synthesis of intracellular cyclic AMP from ATP and is activated by stimulatory G protein alpha subunits (Galpha(s)) and by forskolin (FSK). mACs are inhibited with high potency by 2 '(3')-O-(N-methylanthraniloyl) (MANT)-substituted nucleotides. In this study, the crystal structures of the complex between Galpha(s).GTPgammaS and the catalytic C1 and C2 domains from type V and type II mAC (VC1.IIC2), bound to FSK and either MANT-GTP.Mg(2+) or MANT-GTP.Mn(2+) have been determined. MANT-GTP coordinates two metal ions and occupies the same position in the catalytic site as P-site inhibitors and substrate analogs. However, the orientation of the guanine ring is reversed relative to that of the adenine ring. The MANT fluorophore resides in a hydrophobic pocket at the interface between the VC1 and IIC2 domains and prevents mAC from undergoing the "open" to "closed" domain rearrangement. The K(i) of MANT-GTP for inhibition of VC1.IIC2 is lower in the presence of mAC activators and lower in the presence of Mn(2+) compared with Mg(2+), indicating that the inhibitor binds more tightly to the catalytically most active form of the enzyme. Fluorescence resonance energy transfer-stimulated emission from the MANT fluorophore upon excitation of Trp-1020 in the MANT-binding pocket of IIC2 is also stronger in the presence of FSK. Mutational analysis of two non-conserved amino acids in the MANT-binding pocket suggests that residues outside of the binding site influence isoform selectivity toward MANT-GTP.

About this Structure

1U0H is a Protein complex structure of sequences from Bos taurus, Canis lupus familiaris and Rattus norvegicus with , , , and as ligands. Active as Adenylate cyclase, with EC number 4.6.1.1 Full crystallographic information is available from OCA.

Reference

Structural basis for the inhibition of mammalian membrane adenylyl cyclase by 2 '(3')-O-(N-Methylanthraniloyl)-guanosine 5 '-triphosphate., Mou TC, Gille A, Fancy DA, Seifert R, Sprang SR, J Biol Chem. 2005 Feb 25;280(8):7253-61. Epub 2004 Dec 9. PMID:15591060

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