Cellular and Molecular Life Sciences

, Volume 66, Issue 15, pp 2585–2598

Crystal structures of g-type lysozyme from Atlantic cod shed new light on substrate binding and the catalytic mechanism

Authors

    • Department of Chemistry, The Norwegian Structural Biology CentreUniversity of Tromsø
  • Renate L. Larsen
    • Department of Chemistry, The Norwegian Structural Biology CentreUniversity of Tromsø
  • Solrun Finstad
    • Department of Chemistry, The Norwegian Structural Biology CentreUniversity of Tromsø
  • Peter Kyomuhendo
    • Department of Chemistry, The Norwegian Structural Biology CentreUniversity of Tromsø
    • Nofima Marine
    • Department of Marine Biotechnology, Norwegian College of Fishery ScienceUniversity of Tromsø
Research Article

DOI: 10.1007/s00018-009-0063-x

Cite this article as:
Helland, R., Larsen, R.L., Finstad, S. et al. Cell. Mol. Life Sci. (2009) 66: 2585. doi:10.1007/s00018-009-0063-x

Abstract

Crystal structures of Atlantic cod lysozyme have been solved with and without ligand bound in the active site to 1.7 and 1.9 Å resolution, respectively. The structures reveal the presence of NAG in the substrate binding sites at both sides of the catalytic Glu73, hence allowing the first crystallographic description of the goose-type (g-type) lysozyme E–G binding sites. In addition, two aspartic acid residues suggested to participate in catalysis (Asp101 and Asp90) were mutated to alanine. Muramidase activity data for two single mutants and one double mutant demonstrates that both residues are involved in catalysis, but Asp101 is the more critical of the two. The structures and activity data suggest that a water molecule is the nucleophile completing the catalytic reaction, and the roles of the aspartic acids are to ensure proper positioning of the catalytic water.

Keywords

Atlantic codFish lysozymeCrystal structureActive site residuesSubstrate binding sitesSurface potentialMuramidase activity

Copyright information

© Birkhäuser Verlag, Basel/Switzerland 2009