1ce8

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spinqualitylabelsall models 1ce8, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CARBAMOYL PHOSPHATE SYNTHETASE FROM ESCHERICHIS COLI WITH COMPLEXED WITH THE ALLOSTERIC LIGAND IMP

Overview

Carbamoyl phosphate synthetase (CPS) from Escherichia coli catalyzes the, formation of carbamoyl phosphate, which is subsequently employed in both, the pyrimidine and arginine biosynthetic pathways. The reaction mechanism, is known to proceed through at least three highly reactive intermediates:, ammonia, carboxyphosphate, and carbamate. In keeping with the fact that, the product of CPS is utilized in two competing metabolic pathways, the, enzyme is highly regulated by a variety of effector molecules including, potassium and ornithine, which function as activators, and UMP, which acts, as an inhibitor. IMP is also known to bind to CPS but the actual effect of, this ligand on the activity of the enzyme is dependent upon both, temperature and assay conditions. Here we describe the three-dimensional, architecture of CPS with bound IMP determined and refined to 2.1 A, resolution. The nucleotide is situated at the C-terminal portion of a, five-stranded parallel beta-sheet in the allosteric domain formed by, Ser(937) to Lys(1073). Those amino acid side chains responsible for, anchoring the nucleotide to the polypeptide chain include Lys(954), Thr(974), Thr(977), Lys(993), Asn(1015), and Thr(1017). A series of, hydrogen bonds connect the IMP-binding pocket to the active site of the, large subunit known to function in the phosphorylation of the unstable, intermediate, carbamate. This structural analysis reveals, for the first, time, the detailed manner in which CPS accommodates nucleotide, monophosphate effector molecules within the allosteric domain.

About this Structure

1CE8 is a Protein complex structure of sequences from Escherichia coli with MN, K, CL, PO4, ADP, ORN, IMP and NET as ligands. Active as Carbamoyl-phosphate synthase (glutamine-hydrolyzing), with EC number 6.3.5.5 Full crystallographic information is available from OCA.

Reference

The binding of inosine monophosphate to Escherichia coli carbamoyl phosphate synthetase., Thoden JB, Raushel FM, Wesenberg G, Holden HM, J Biol Chem. 1999 Aug 6;274(32):22502-7. PMID:10428826

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