The Preparation and Properties of Recombinant Forms of GH74 Family Xyloglucanase from the Trichoderma reesei Fungus

Cloning and expression of the full-length endo-processive-type xyloglucanase from the Trichoderma reesei (TrXeg74A) fungus, as well as its catalytic domain TrXeg74A-CD, in the Penicillium verruculosum B1-537 recipient strain have been carried out. P. verruculosum is a highly effective producer of cellulases. The levels of protein secretion after culturing the obtained recombinant strains in a laboratory fermenter were 35.4 and 31.4 g/L, respectively. TrXeg74A accounted for at least 30% of the total protein, while TrXeg74A-CD was expressed to a much lesser extent. Both forms of the recombinant enzyme were isolated in purified state and their properties were studied. TrXeg74A and TrXeg74A-CD were characterized by a similar degree of processivity when exposed to tamarind xyloglucan and the same Michaelis constant (0.35-0.38 g/L), close to that for the native enzyme (0.30 g/L), while the catalytic constant for TrXeg74A-CD was 1.5 times higher than the corresponding parameter for full-length xyloglucanase. The obtained new recombinant P. verruculosum strains can be useful in the development of composite enzyme preparations for efficient hydrolysis of renewable lignocellulosic raw materials.