(A) Swarming of the fliH null mutant with pET19b-based and pTrc99A-based plasmids encoding the proteins shown. V, vector. Plates were incubated for 4.5 h at 30°C. (B) Immunoblot, using anti-His antibody, of whole cells of the fliH null mutant transformed with plasmids encoding the proteins shown. (C) Immunoblot, using polyclonal anti-FlgD antibody, of the hook-capping protein FlgD in culture supernatants of the fliH mutant transformed with plasmids encoding the proteins indicated. Cellular levels of FlgD were the same in all cases (data not shown).

(A) Swarming of the fliH null mutant transformed with pTrc99A-based plasmids encoding the truncation variants of FliI shown (see Fig. 1B). Plates were incubated for 4.5 h at 30°C. (B) Immunoblot, using anti-His antibody, of whole-cell proteins of the fliH null mutant transformed with the same plasmids as in panel A. V, vector.

Swarming of the fliH null mutant MKM11 and the fliH frameshift mutant SJW1429 (see Fig. 1B) transformed with pTrc99A-based plasmids encoding His-FliH, His-FliI, and His-FliH plus His-FliI. v, vector. Plates were incubated for 4.5 h at 30°C.

(A) The primary structure of the ATPase regulatory protein FliH and schematic representation of mutant FliH proteins produced by MKM11 and SJW1429. FliH is a 235-amino-acid protein that can be roughly divided into three regions: an N-terminal region consisting of the first 100 amino acids, a middle region containing amino acid residues 101 to 140, and a C-terminal region comprising the remainder of the protein. The N-terminal region, middle, and C-terminal regions are essential for interaction with FliJ, for dimerization, and for interaction with FliI, respectively. (B) The primary structure of the flagellum-specific ATPase FliI and schematic representations of the FliI products produced by the plasmids listed in Table 1.

(A) Swarming of the fliH null mutant transformed with plasmids encoding the point mutant FliI variants shown. Plates were incubated for 4.5 h at 30°C. (B) Immunoblot, using anti-FlgD antibody, of the culture supernatant fractions of the fliH null mutant transformed with plasmids encoding the point mutant FliI variants shown. V, vector.

(A) Swarming of the fliH null mutant transformed with pTrc99A-based plasmids encoding 10-amino-acid deletion derivatives of FliI. Plates were incubated for 5 h at 30°C. V, vector. (B) Immunoblot, using anti-His antibody, of whole-cell proteins of HMS174(DE3)pLysS transformed with the same plasmids as in panel A.

(A) Swarming of MKM11 (ΔfliH) and pseudorevertants MMA1002 (ΔfliH flhA*) and MMB1005 (ΔfliH flhB*). (B) Swarming of SJW1103 (wild type) and second-site mutants MMA1102 (flhA*) and MMB1105 (flhB*). The plates were incubated at 30°C for the times indicated.