2EPL: N-acetyl-b-d-glucosaminidase (gcna) From Streptococcus Gordonii

Citation:
Abstract
The crystal structure of GcnA, an N-acetyl-beta-D-glucosaminidase from Streptococcus gordonii, was solved by multiple wavelength anomalous dispersion phasing using crystals of selenomethionine-substituted protein. GcnA is a homodimer with subunits each comprised of three domains. The structure of the C-terminal alpha-helical domain has not been observed previously and forms a large dimerisation interface. The fold of the N-terminal domain is observed in all structurally related glycosidases although its function is unknown. The central domain has a canonical (beta/alpha)(8) TIM-barrel fold which harbours the active site. The primary sequence and structure of this central domain identifies the enzyme as a family 20 glycosidase. Key residues implicated in catalysis have different conformations in two different crystal forms, which probably represent active and inactive conformations of the enzyme. The catalytic mechanism for this class of glycoside hydrolase, where the substrate rather than the enzyme provides the cleavage-inducing nucleophile, has been confirmed by the structure of GcnA complexed with a putative reaction intermediate analogue, N-acetyl-beta-D-glucosamine-thiazoline. The catalytic mechanism is discussed in light of these and other family 20 structures.
PDB ID: 2EPLDownload
MMDB ID: 62883
PDB Deposition Date: 2007/3/30
Updated in MMDB: 2012/12
Experimental Method:
x-ray diffraction
Resolution: 1.4  Å
Source Organism:
Similar Structures:
Biological Unit for 2EPL: dimeric; determined by author and by software (PISA,PQS)
Molecular Components in 2EPL
Label Count Molecule
Proteins (2 molecules)
2
N-acetyl-beta-d-glucosaminidase
Molecule annotation
Chemicals (18 molecules)
1
16
2
2
* Click molecule labels to explore molecular sequence information.

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