Reference : The structure of a cold-adapted family 8 xylanase at 1.3 angstrom resolution - Struct...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
The structure of a cold-adapted family 8 xylanase at 1.3 angstrom resolution - Structural adaptations to cold and investigation of the active site
Van Petegem, F. [> > > >]
Collins, T. [> > > >]
Meuwis, Marie-Alice mailto [Université de Liège - ULiège > > GIGA-Management : Plate-forme protéomique >]
Gerday, Charles mailto [Université de Liège - ULiège > Services généraux (Faculté des sciences) > Relations académiques et scientifiques (Sciences) >]
Feller, Georges mailto [Université de Liège - ULiège > Département des sciences de la vie > Labo de biochimie >]
Van Beeumen, J. [> > > >]
Journal of Biological Chemistry
Amer Soc Biochemistry Molecular Biology Inc
Yes (verified by ORBi)
[en] Enzymes from psychrophilic organisms differ from their mesophilic counterparts in having a lower thermo-stability and a higher specific activity at low and moderate temperatures. The current consensus is that they have an increased flexibility, enhancing accommodation and transformation of the substrates at low energy costs. Here we describe the structure of the xylanase from the Antarctic bacterium Pseudoalteromonas haloplanktis at 1.3 Angstrom resolution. Xylanases are usually grouped into glycosyl hydrolase families 10 and 11, but this enzyme belongs to family 8. The fold differs from that of other known xylanases and can be described as an (alpha/alpha)(6) barrel. Various parameters that may explain the cold-adapted properties were examined and indicated that the protein has a reduced number of salt bridges and an increased exposure of hydrophobic residues. The crystal structures of a complex with xylobiose and of mutant D144N were obtained at 1.2 and 1.5 A resolution, respectively. Analysis of the various substrate binding sites shows that the +3 and -3 subsites are rearranged as compared to those of a family 8 homolog, while the xylobiose complex suggests the existence of a +4 subsite. A decreased acidity of the substrate binding cleft and an increased flexibility of aromatic residues lining the subsites may enhance the rate at which substrate is bound.

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