A putative laccase gene was cloned from Shigella dysenteriae W202 and expressed in Escherichia coli as a soluble fusion protein with high yield. The purified product (Wlac) was characterized as the CueO-like laccase from E. coli, a monomer of molecular mass 55kDa, with a maximum activity of 24.4U/mg (K m =0.086) and a pH optimum of 2.5, in a standard assay using ABTS (2,2′-azino-di(3-ethyl-benzthiazoline-6-sulfonate) as the substrate. Activity was stable at 0–25°C but inhibited above 40°C. Purified Wlac was completely inhibited by 200mM EDTA and partially by 32mM SDS, 50mM NaN 3 and 60mM thioglycolic acid. Activity was stimulated by Cu 2+ ; other metal ions had only slight or negative effects. Two mutated variants, WlacS and WlacD, were obtained by substituting Glu 106 with Phe 106, and adding a deletion of an α-helix domain (from Leu 351 to Gly 378). WlacS had a 2.2-fold (52.9U/mg) and WlacD a 3.5-fold (85.1U/mg) higher enzyme activity than the wild-type laccase and WlacD showed greater thermostability at higher temperatures. Sce VMA intein-associated fusion proteins maintained ∼80% of total enzyme activity. Thus, deletion and site-directed mutagenesis of laccases are capable of promoting both enzymatic activity and thermostability.