prgI and prgJ are required for needle
structure formation. (A) Western-blot analysis of whole
cell lysate (C), culture supernatant (S), and postCsCl needle complex
fractions (NC) isolated from WT Salmonella (TK328). The
amount of C and S fractions loaded represents equivalent amounts of
total culture volume (0.2 ml), the NC represents 25 ml of culture. The
blot was probed with polyclonal antiserum against PrgH, PrgI, PrgJ,
PrgK, and InvJ as indicated. (B) Western blot analysis
of PreCsCl NC fractions isolated from WT and prg
deletion strains: WT (TK328), ΔH (TK334), ΔI (TK335), ΔJ (TK336),
ΔK (TK337), ΔH-K (TK338). The blot was probed with polyclonal
antiserum against PrgH, PrgI, PrgJ, and PrgK as indicated.
(C) Electron micrographs of NC isolated from WT (TK328).
Complexes came from same fraction (NC) analyzed in A.
Samples were negatively stained with 2% PTA (pH 7.2) and observed
under a JEM-1200EXII transmission electron microscope. Approximate
sizes of the NC are listed in the schematic (D)
(n = 30). (Scale bar, 50 nm.) (D)
Electron micrographs of partial NC isolated from WT (TK328), ΔprgI
(TK335), and ΔprgJ (TK336) deletion mutants. A schematic comparing
the size and morphology of these structures to WT structures is also
shown. Approximate sizes are given in schematic (n
= 30). (Scale bars, 50 nm and 25 nm.)