A. Immunoprecipitation of chromosomally tagged GltA::HA combined with either an empty vector control (pCtrl) or SPA-tagged vcdP over-expression plasmid, grown in LB medium to exponential phase (OD600 of 0.5). The SPA epitope contains the 3×FLAG and the calmodulin binding peptide sequences separated by a TEV protease cleavage site (Zeghouf et al, 2004). Therefore, protein samples corresponding to the total input and cell lysates before and after subjecting to immunoprecipitation with anti-Flag antibody were loaded on a SDS-PAGE gel. Western blotting with anti-HA and anti-Flag antibodies confirmed the interaction of GltA with VcdP in vivo. RNAP served as loading control. The solid triangles indicate the corresponding protein sizes. 