Purification of dimeric and tetrameric forms of EsxRS. (A) Typical chromatographic profile for preparative SEC of EsxRS. Peak 1 contains an EsxRS complex with a molecular mass consistent with a tetramer while peak 2 contains an EsxRS complex with a molecular mass consistent with a dimer. (B) SDS—PAGE (20% gel) analysis of the two peaks from SEC purification. Lane M, Broad-range molecular weight markers; lane 1, peak 1 from SEC purification; lane 2, peak 2 from SEC purification. EsxRS complexes exist in two distinct oligomeric states, dimer and tetramer, that contain the EsxR and EsxS subunits in equal amounts.