Note: In the PDB file this reference is
annotated as "TO BE PUBLISHED". The citation details given above have
been manually determined.
Abstract
The hyperthermophilic glycoside hydrolase family endocellulase 12 from the
archaeon Pyrococcus furiosus (EGPf; Gene ID PF0854; EC 3.2.1.4) catalyzes the
hydrolytic cleavage of the β-1,4-glucosidic linkage in β-glucan in
lignocellulose biomass. A crystal of EGPf was previously prepared at pH 9.0 and
its structure was determined at an atomic resolution of 1.07 Å. This article
reports the crystallization of EGPf at the more physiologically relevant pH of
5.5. Structure determination showed that this new crystal form has the symmetry
of space group C2. Two molecules of the enzyme are observed in the asymmetric
unit. Crystal packing is weak at pH 5.5 owing to two flexible interfaces between
symmetry-related molecules. Comparison of the EGPf structures obtained at pH 9.0
and pH 5.5 reveals a significant conformational difference at the active centre
and in the surface loops. The interfaces in the vicinity of the flexible surface
loops impact the quality of the EGPf crystal.
