Download MendeleyCrystal structures of Trichoderma reesei beta-galactosidase reveal conformational changes in the active site
Maksimainen, M., Hakulinen, N., Kallio, J.M., Timoharju, T., Turunen, O., Rouvinen, J.(2011) J Struct Biol 174: 156-163
- PubMed: 21130883
- DOI: https://doi.org/10.1016/j.jsb.2010.11.024
- Primary Citation of Related Structures:
3OG2, 3OGR, 3OGS, 3OGV - PubMed Abstract:
We have determined the crystal structure of Trichoderma reesei (Hypocrea jecorina) ¦Â-galactosidase (Tr-¦Â-gal) at a 1.2? resolution and its complex structures with galactose, IPTG and PETG at 1.5, 1.75 and 1.4? resolutions, respectively. Tr-¦Â-gal is a potential enzyme for lactose hydrolysis in the dairy industry and belongs to family 35 of the glycoside hydrolases (GH-35). The high resolution crystal structures of this six-domain enzyme revealed interesting features about the structure of Tr-¦Â-gal. We discovered conformational changes in the two loop regions in the active site, implicating a conformational selection-mechanism for the enzyme. In addition, the Glu200, an acid/base catalyst showed two different conformations which undoubtedly affect the pK(a) value of this residue and the catalytic mechanism. The electron density showed extensive glycosylation, suggesting a structure stabilizing role for glycans. The longest glycan showed an electron density that extends to the eighth monosaccharide unit in the extended chain. The Tr-¦Â-gal structure also showed a well-ordered structure for a unique octaserine motif on the surface loop of the fifth domain.
Organizational Affiliation:
Department of Chemistry, University of Eastern Finland, P.O. Box 111, FIN-80101 Joensuu, Finland.
