1zps

File:1zps.gif

spinqualitylabelsall models 1zps, resolution 1.7Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of Methanobacterium thermoautotrophicum phosphoribosyl-AMP cyclohydrolase HisI

OverviewOverview

The metabolic pathway for histidine biosynthesis is interesting from an, evolutionary perspective because of the diversity of gene organizations, and protein structures involved. Hydrolysis of phosphoribosyl-AMP, the, third step in the histidine biosynthetic pathway, is carried out by PR-AMP, cyclohydrolase, the product of the hisI gene. The three-dimensional, structure of PR-AMP cyclohydrolase from Methanobacterium, thermoautotrophicum was solved and refined to 1.7 A resolution. The enzyme, is a homodimer. The position of the Zn(2+)-binding site that is essential, for catalysis was inferred from the positions of bound Cd(2+) ions, which, were part of the crystallization medium. These metal binding sites include, three cysteine ligands, two from one monomer and the third from the second, monomer. The enzyme remains active when Cd(2+) is substituted for Zn(2+)., The likely binding site for Mg(2+), also necessary for activity in a, homologous cyclohydrolase, was also inferred from Cd(2+) positions and is, comprised of aspartic acid side chains. The putative substrate-binding, cleft is formed at the interface between the two monomers of the dimer., This fact, combined with the localization of the Zn(2+)-binding site, indicates that the enzyme is an obligate dimer.

About this StructureAbout this Structure

1ZPS is a Single protein structure of sequence from Methanothermobacter thermautotrophicus with CD and ACY as ligands. Active as Phosphoribosyl-AMP cyclohydrolase, with EC number 3.5.4.19 Full crystallographic information is available from OCA.

ReferenceReference

Crystal structure of Methanobacterium thermoautotrophicum phosphoribosyl-AMP cyclohydrolase HisI., Sivaraman J, Myers RS, Boju L, Sulea T, Cygler M, Jo Davisson V, Schrag JD, Biochemistry. 2005 Aug 2;44(30):10071-80. PMID:16042384

Page seeded by OCA on Wed Nov 21 07:35:35 2007