CC30 strains produce a variant of PSMα3.

<p>(A,B) Mass spectrogram of the region where PSMα3 elutes during RP-HPLC/MS of the culture filtrate of a non-CC30 strain (USA300) (A) or a CC30 strain (B), respectively. The peak corresponding to PSMα3 is marked in red. Other peaks are from co-eluting PSM peptides. (C) PSMα3N22Y production in a collection of historic and contemporary CC30 strains. Strains shown in red contain a mutation in <i>agrC</i> that is characteristic of contemporary CC30 strains. Production of PSMα3 in strain LAC (USA300) is shown as comparison.