4UTT: Structural Characterisation Of Nane, Mannac6p C2 Epimerase, From Clostridium Perfingens

Citation:
Abstract
Pathogenic bacteria are endowed with an arsenal of specialized enzymes to convert nutrient compounds from their cell hosts. The essential N-acetylmannosamine-6-phosphate 2-epimerase (NanE) belongs to a convergent glycolytic pathway for utilization of the three amino sugars, GlcNAc, ManNAc, and sialic acid. The crystal structure of ligand-free NanE from Clostridium perfringens reveals a modified triose-phosphate isomerase (beta/alpha)8 barrel in which a stable dimer is formed by exchanging the C-terminal helix. By retaining catalytic activity in the crystalline state, the structure of the enzyme bound to the GlcNAc-6P product identifies the topology of the active site pocket and points to invariant residues Lys(66) as a putative single catalyst, supported by the structure of the catalytically inactive K66A mutant in complex with substrate ManNAc-6P. (1)H NMR-based time course assays of native NanE and mutated variants demonstrate the essential role of Lys(66) for the epimerization reaction with participation of neighboring Arg(43), Asp(126), and Glu(180) residues. These findings unveil a one-base catalytic mechanism of C2 deprotonation/reprotonation via an enolate intermediate and provide the structural basis for the development of new antimicrobial agents against this family of bacterial 2-epimerases.
PDB ID: 4UTTDownload
MMDB ID: 124217
PDB Deposition Date: 2014/7/23
Updated in MMDB: 2014/11
Experimental Method:
x-ray diffraction
Resolution: 1.71  Å
Source Organism:
Similar Structures:
Biological Unit for 4UTT: dimeric; determined by software (PISA)
Molecular Components in 4UTT
Label Count Molecule
Proteins (2 molecules)
1
Putative N-acetylmannosamine-6-phosphate 2-epimerase(Gene symbol: CPF_RS00900)
Molecule annotation
1
Putative N-acetylmannosamine-6-phosphate 2-epimerase(Gene symbol: CPF_RS00900)
Molecule annotation
Chemicals (6 molecules)
1
4
2
2
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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