FIGURE 1.

MamK forms filaments in the presence of ATP. A, MamK polymerizes in the presence of ATP but not ADP. MamK polymerization was assessed by pelleting assays as described under “Experimental Procedures;” pellet (P) and supernatant (S) fractions were analyzed. Nucleotide was added to MamK (40 μm) to a final concentration of 5 mm. Experiments were performed in the presence of 5 mm nucleotide and 1 mm MgCl₂; however, similar results were obtained in the presence of excess (2 mm nucleotide, 5 mm MgCl₂) or equimolar levels of MgCl₂ (5 mm nucleotide, 5 mm MgCl₂) (data not shown). B, negatively stained MamK filaments as visualized by transmission EM.