FIG. 3.

R388 TrwD forms hexameric rings. TrwD (50 ng/μl) was preincubated in 20 mM Tris-HCl [pH 7.6], 100 mM NaCl, 1 mM ATP, and 10 mM MgCl₂ for 10 min at room temperature. Samples were stained with 1% uranyl acetate (12) and were observed in a Phillips CM 100 electron microscope. Bar, 100 nm. Arrows indicate ring-shaped molecules and arrow heads indicate tube-like structures.