A trimeric and thermostable lichenase from B. pumilus US570 strain: Biochemical and molecular characterization

New β-1,3;1,4-glucanase (GluUS570) was purified from a newly isolated Bacillus pumilus US570 strain. The enzyme was active in a wide range of pH and temperature and displayed a great thermostability with a half-life of 30 min at 80 °C. The enzyme was demonstrated to be a lichenase since it was only active toward glucan containing β-1,3;1,4- linkages. The analysis of the enzyme in native and denaturing conditions suggests that it has a trimeric form (75 kDa). This is the first report on the purification and characterization of a bacterial lichenase with a trimeric structure. β-1,3;1,4-glucanase encoding gene was amplified, cloned and sequenced showing an open reading frame of 732 bp encoding 243 amino acids. The GluUS570 enzyme showed 97% homology with glucanase from Bacillus lichenoformis. The 3D model of GluUS570 in trimeric form was generated and showed that a region named R2 was involved in the oligomerization of the enzyme.