Fig. S8.

Alignment of SSL3 and SSL4. Sequence alignment highlighting residues found in the TLR2 binding interface of SSL3 from S. aureus strain NCTC 8325 and their conservation in SSL4 from the same strain and SSL3 and SSL4 from strain MRSA252. Nearly all of the SSL3 amino acids involved in TLR2 interactions are present in SSL4 MRSA252, explaining its enhanced TLR2 inhibitory activity with respect to SSL4 from strain NCTC 8325 (5). However, SSL3 from MRSA252 contains only one of the seven conserved amino acids, indicating that genetic recombination may have occurred in this strain that switched the activity between its SSL3 and SSL4. The length of the proteins, however, corresponds more closely to their original family members, with both SSL3s having the longer N-terminal domain. SSL3 and SSL4 have been assigned based on their gene order in the genomes of NCTC 8325 (SAOUHSC_00386 and SAOUHSC_00389) and MRSA252 (SAR_RS02110 and SAR_RS02115).