Crystal structure of glycosylasparaginase from Flavobacterium meningosepticum.

The crystal structure of recombinant glycosylasparaginase from Flavobacterium meningosepticum has been determined at 2.32 angstroms resolution. This enzyme is a glycoamidase that cleaves the link between the asparagine and the N-acetylglucosamine of N-linked oligosaccharides and plays a major role in the degradation of glycoproteins. The three-dimensional structure of the bacterial enzyme is very similar to that of the human enzyme, although it lacks the four disulfide bridges found in the human enzyme. The main difference is the absence of a small random coil domain at the end of the alpha-chain that forms part of the substrate binding cleft and that has a role in the stabilization of the tetramer of the human enzyme. The bacterial glycosylasparaginase is observed as an (alphabeta)2-tetramer in the crystal, despite being a dimer in solution. The study of the structure of the bacterial enzyme allows further evaluation of the effects of disease-causing mutations in the human enzyme and confirms the suitability of the bacterial enzyme as a model for functional analysis.