2ZUS: Crystal Structure Of Galacto-n-biose/lacto-n-biose I Phosphorylase

Galacto-N-biose/lacto-N-biose I phosphorylase (GLNBP) from Bifidobacterium longum, a key enzyme for intestinal growth, phosphorolyses galacto-N-biose and lacto-N-biose I with anomeric inversion. GLNBP homologues are often found in human pathogenic and commensal bacteria, and their substrate specificities potentially define the nutritional acquisition ability of these microbes in their habitat. We report the crystal structures of GLNBP in five different ligand-binding forms. This is the first three-dimensional structure of glycoside hydrolase (GH) family 112. The GlcNAc- and GalNAc-bound forms provide structural insights into distinct substrate preferences of GLNBP and its homologues from pathogens. The catalytic domain consists of a partially broken TIM barrel fold that is structurally similar to a thermophilic beta-galactosidase, strongly supporting the current classification of GLNBP homologues as one of the GH families. Anion binding induces a large conformational change by rotating a half-unit of the barrel. This is an unusual example of molecular adaptation of a TIM barrel scaffold to substrates.
PDB ID: 2ZUSDownload
MMDB ID: 68761
PDB Deposition Date: 2008/10/28
Updated in MMDB: 2008/12
Experimental Method:
x-ray diffraction
Resolution: 2.11  Å
Source Organism:
Similar Structures:
Biological Unit for 2ZUS: dimeric; determined by author and by software (PISA)
Molecular Components in 2ZUS
Label Count Molecule
Proteins (2 molecules)
Lacto-n-biose Phosphorylase
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

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