title: Crystal structure of the tetrameric inositol 1-phosphate phosphatase (TM1415) from the hyperthermophile, Thermotoga maritima.
abstract: The structure of the first tetrameric inositol monophosphatase (IMPase) has been solved. This enzyme, from the eubacterium Thermotoga maritima, similarly to its archaeal homologs exhibits dual specificity with both IMPase and fructose-1,6-bisphosphatase activities. The tetrameric structure of this unregulated enzyme is similar, in its quaternary assembly, to the allosterically regulated tetramer of fructose-1,6-bisphosphatase. The individual dimers are similar to the human IMPase. Additionally, the structures of two crystal forms of IMPase show significant differences. In the first crystal form, the tetrameric structure is symmetrical, with the active site loop in each subunit folded into a beta-hairpin conformation. The second form is asymmetrical and shows an unusual structural change. Two of the subunits have the active site loop folded into a beta-hairpin structure, whereas in the remaining two subunits the same loop adopts an alpha-helical conformation.
authors.affiliation: Merkert Chemistry Center, Boston College, Chestnut Hill, MA, USA.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Stieglitz
authors.forename: Mary F
authors.initials: MF
authors.lastname: Roberts
authors.forename: Weizhong
authors.initials: W
authors.lastname: Li
authors.forename: Boguslaw
authors.initials: B
authors.lastname: Stec
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D019143:Evolution, Molecular; D006597:Fructose-Bisphosphatase / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D020124:Thermotoga maritima / Q000201:enzymology*
chemical_list: D006597:Fructose-Bisphosphatase; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase