FIG. 4.
Immunoblot analyses of the FrzCD methylation patterns in csgA and ΔdevT csgA cells in response to exogenous MalE-CsgA protein. Total cell lysates were prepared from cells that had been starved for 6 h in submerged culture, brought into suspension, and exposed to the indicated amounts of MalE-CsgA fusion protein for 30 min while in suspension. Subsequently, proteins were reacted with anti-FrzCD antibody. (Left panel) Proteins isolated from DK5208 (csgA) cells; (right panel) proteins isolated from SA1301(ΔdevT csgA) cells. Protein from 5 × 107 cells were added to each lane. The two upper bands represent nonmethylated FrzCD (indicated by the open arrows), and the three lower bands represent methylated FrzCD (indicated by the solid arrows). One C-factor unit is the amount of protein that restores wt fruiting body formation and sporulation to 2.5 × 108 csgA cells (17).