Crystallization and preliminary X-ray diffraction analysis of the invertase from Saccharomyces cerevisiae.

Saccharomyces cerevisiae invertase (ScInv) is an enzyme encoded by the SUC2 gene that releases ß-fructose from the nonreducing termini of various ß-D-fructofuranoside substrates. Its ability to produce 6-kestose by transglycosylation makes this enzyme an interesting research target for applications in industrial biotechnology. The native enzyme, which presents a high degree of oligomerization, was crystallized by vapour-diffusion methods. The crystals belonged to space group P3(1)21, with unit-cell parameters a=268.6, b=268.6, c=224.4 Å. The crystals diffracted to 3.3 Šresolution and gave complete data sets using a synchrotron X-ray source.

Crystallization and preliminary X-ray diffraction analysis of the fructofuranosidase from Xanthophyllomyces dendrorhous.

Xanthophyllomyces dendrorhous invertase is an extracellular enzyme that releases ß-fructose from the nonreducing termini of various ß-D-fructofuranoside substrates. Its ability to produce neokestose by transglycosylation makes this enzyme an interesting research target for applications in industrial biotechnology. The native enzyme, which is highly glycosylated, failed to crystallize. Therefore, it was submitted to EndoH deglycosylating treatment and crystals were grown by vapour-diffusion methods. The crystals belonged to space group P2(1)2(1)2, with unit-cell parameters a = 75.29, b = 204.93, c = 146.25 Å. Several diffraction data sets were collected using a synchrotron source. Self-rotation function and gel-filtration experiments suggested that the enzyme is a dimer with twofold symmetry.

Structural and kinetic analysis of Schwanniomyces occidentalis invertase reveals a new oligomerization pattern and the role of its supplementary domain in substrate binding.

Schwanniomyces occidentalis invertase is an extracellular enzyme that hydrolyzes sucrose and releases beta-fructose from various oligosaccharides and essential storage fructan polymers such as inulin. We report here the three-dimensional structure of Sw. occidentalis invertase at 2.9 A resolution and its complex with fructose at 1.9 A resolution. The monomer presents a bimodular arrangement common to other GH32 enzymes, with an N-terminal 5-fold beta-propeller catalytic domain and a C-terminal beta-sandwich domain for which the function has been unknown until now. However, the dimeric nature of Sw. occidentalis invertase reveals a unique active site cleft shaped by both subunits that may be representative of other yeast enzymes reported to be multimeric. Binding of the tetrasaccharide nystose and the polymer inulin was explored by docking analysis, which suggested that medium size and long substrates are recognized by residues from both subunits. The identified residues were mutated, and the enzymatic activity of the mutants against sucrose, nystose, and inulin were investigated by kinetic analysis. The replacements that showed the largest effect on catalytic efficiency were Q228V, a residue putatively involved in nystose and inulin binding, and S281I, involved in a polar link at the dimer interface. Moreover, a significant decrease in catalytic efficiency against inulin was observed in the mutants Q435A and Y462A, both located in the beta-sandwich domain of the second monomer. This highlights the essential function that oligomerization plays in substrate specificity and assigns, for the first time, a direct catalytic role to the supplementary domain of a GH32 enzyme.

Crystallization and preliminary X-ray diffraction analysis of the fructofuranosidase from Schwanniomyces occidentalis.

Schwanniomyces occidentalis invertase is an extracellular enzyme that releases beta-fructose from the nonreducing termini of various beta-d-fructofuranoside substrates. Its ability to produce 6-kestose by transglycosylation makes this enzyme an interesting research target for applications in industrial biotechnology. The enzyme has been expressed in Saccharomyces cerevisiae. Recombinant and wildtype forms, which showed different glycosylation patterns, were crystallized by vapour-diffusion methods. Although crystallization trials were conducted on both forms of the protein, crystals suitable for X-ray crystallographic analyses were only obtained from the wild-type enzyme. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 105.78, b = 119.49, c = 137.68 angstrom. A diffraction data set was collected using a synchrotron source. Self-rotation function and sedimentation-velocity experiments suggested that the enzyme was dimeric with twofold symmetry.