An arrow depicts the situation of the peptide binding clefts. (B) Topology diagrams of SipA and E. coli SPase-I, colour-coded as for the ribbon diagram
Despite the fact that SipA lacks the catalytic residues of SPase-I, it retains the peptide-binding cleft found in E. coli SPase-I (Figure 2). This cleft, which is formed by residues…