title: Structural basis for the function of Bacillus subtilis phosphoribosyl-pyrophosphate synthetase.
abstract: Here we report the first three-dimensional structure of a phosphoribosylpyrophosphate (PRPP) synthetase. PRPP is an essential intermediate in several biosynthetic pathways. Structures of the Bacillus subtilis PRPP synthetase in complex with analogs of the activator phosphate and the allosteric inhibitor ADP show that the functional form of the enzyme is a hexamer. The individual subunits fold into two domains, both of which resemble the type I phosphoribosyltransfereases. The active site is located between the two domains and includes residues from two subunits. Phosphate and ADP bind to the same regulatory site consisting of residues from three subunits of the hexamer. In addition to identifying residues important for binding substrates and effectors, the structures suggest a novel mode of allosteric regulation.
authors.affiliation: Center for Crystallographic Studies, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
authors.forename: T A
authors.initials: TA
authors.lastname: Eriksen
authors.forename: A
authors.initials: A
authors.lastname: Kadziola
authors.forename: A K
authors.initials: AK
authors.lastname: Bentsen
authors.forename: K W
authors.initials: KW
authors.lastname: Harlow
authors.forename: S
authors.initials: S
authors.lastname: Larsen
mesh_terms: D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D000495:Allosteric Site; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology*; D001665:Binding Sites; D020134:Catalytic Domain; D003460:Crystallization; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012268:Ribose-Phosphate Pyrophosphokinase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D013431:Sulfates / Q000378:metabolism
chemical_list: D013431:Sulfates; C523965:alpha,beta-methyleneadenosine 5'-diphosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D012268:Ribose-Phosphate Pyrophosphokinase