FIG. 4.

Electron micrographs of R. lupini and S. meliloti wild-type and mutant flagellar filaments negatively stained with uranyl acetate. Wild-type R. lupini (A) and S. meliloti (D) complex flagellar filaments are dominated by a prominent three-start helical band pattern (zigzag pattern). Mutant filaments lacking the FlaA subunit from either R. lupini (B) or S. meliloti (E) are shown. Their complex surface structures appear to be normal (C and F). Bars: 100 nm (A, C, D, and F) and 500 nm (B and E).