Physico-chemical properties and substrate specificity of α-(1→3)- <scp>d</scp> -glucan degrading recombinant mutanase from <i>Trichoderma harzianum</i> expressed in <i>Penicillium verruculosum</i>

The manuscript describes the properties of a novel recombinant GH71 mutanase Mut A from <i>Trichoderma harzianum</i>. Gene <i>mutAW</i> encoding mutanase was heterologously expressed in the host strain <i>Penicillium verruculosum</i> B1-537 (ΔniaD). The recipient strain has a high secretory ability and allowed to obtain preparations containing the target recombinant enzyme up to 80% of the total protein pool. MutA exhibited a high activity against mutan and negligible or zero activity toward other types of glucans including α-(1→4)-, β-(1→3)-, β-(1→4)-, and β-(1→6)-glucans. By using a series of synthetic oligo-α-(1→3)-D-glucosides, we demonstrated that MutA is an endo-processive enzyme, which hydrolyzes the internal glucosidic bonds and releases glucose from the reducing end sliding into the non-reducing end. MutA recognizes tetrasaccharide as a minimal substrate and hydrolyzes it to trisaccharide and glucose. The effectiveness of the use of MutA for the destruction of clinical isolates of gram-positive and gram-negative bacteria is also described.