Functional and structural characterization of a novel putative cysteine protease cell wall-modifying multi-domain enzyme selected from a microbial metagenome by Faheem, M, Martins-de-Sa, D, Vidal, J, Álvares, A, Brandão-Neto, J, Bird, L, Tully, M, von Delft, F, Souto, B, Quirino, B, Freitas, S, Barbosa, J