Figure 3.

Western blot analyses of expression of ExoK (A and B) and ExsH (C and D) by R. meliloti strains. Lanes contain either the cells (without supernatant) from the equivalent of 10 μl of culture (A and C) or 5 μl of cell-free supernatant (B and D). Strains were cultured either in MGS medium (A and B) or GMS medium (C and D). We used exoY mutant strains, which fail to produce succinoglycan, to enable the high efficiency removal of cells from culture supernatants by centrifugation. Strains: 1, exoY; 2, exoY exoK; 3, exoY exsH; 4, exoY exoK exsH; 5, exoY prsD; and 6, exoY prsE. Lines indicate positions of molecular mass markers (kDa). Arrow for C indicates the position of protein band corresponding to ExsH, which is resolved poorly from another R. meliloti protein.