A 1569 bp PCR-amplified wlac was obtained from S. dysenteriae W202. Sequences analysis indicated that this was in an intact encoding frame, with the highest similarity being to a yacK gene (the encoded product is uncertain) of S. dysenteriae Sd197 strain (99%, GenBank accession number CP000034), and then compared to the multicopper oxidases of several E. coli strains (97%). To investigate if the expression product of the cloned wlac has a similar effect to that of E. coli CueO, wlac was ligated to E. coli expression vector pTYB12 (to give the recombinant plasmid pMB170) and then transferred into an E. coli ER2566 recipient for further purification.