title: Allosteric inhibition via R-state destabilization in ATP sulfurylase from Penicillium chrysogenum.
abstract: The structure of the cooperative hexameric enzyme ATP sulfurylase from Penicillium chrysogenum bound to its allosteric inhibitor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS), was determined to 2.6 A resolution. This structure represents the low substrate-affinity T-state conformation of the enzyme. Comparison with the high substrate-affinity R-state structure reveals that a large rotational rearrangement of domains occurs as a result of the R-to-T transition. The rearrangement is accompanied by the 17 A movement of a 10-residue loop out of the active site region, resulting in an open, product release-like structure of the catalytic domain. Binding of PAPS is proposed to induce the allosteric transition by destabilizing an R-state-specific salt linkage between Asp 111 in an N-terminal domain of one subunit and Arg 515 in the allosteric domain of a trans-triad subunit. Disrupting this salt linkage by site-directed mutagenesis induces cooperative inhibition behavior in the absence of an allosteric effector, confirming the role of these two residues.
authors.affiliation: Section of Molecular and Cellular Biology, University of California, One Shields Avenue, Davis, California 95616, USA.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: MacRae
authors.forename: Irwin H
authors.initials: IH
authors.lastname: Segel
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Fisher
mesh_terms: D000494:Allosteric Regulation; D000495:Allosteric Site; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D007700:Kinetics; D008958:Models, Molecular; D009038:Motion; D016297:Mutagenesis, Site-Directed; D010408:Penicillium chrysogenum / Q000201:enzymology*; D010724:Phosphoadenosine Phosphosulfate / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013430:Sulfate Adenylyltransferase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010724:Phosphoadenosine Phosphosulfate; D013430:Sulfate Adenylyltransferase