Fig. (1) Amino acid sequence alignment of SeMac and GAS M1 Mac. The conserved Cys (C), His (H), and Asp (D) constituting the catalytic triad are highlighted in red and underlined. Amino acid residues of GAS Mac identical to those in SeMac (·) and gaps introduced to maximize alignment (-) are indicated. The arrow indicates the presumed cleavage site of the secretion signal sequence.