PrgH and PrgK form the inner membrane rings of the NC.
(A and B) Representative electron
micrograph images of PrgH/PrgK complexes from recombinant E.
coli (DH5α) expressing
prgH/prgK (pTK42) or
prgHIJK (pTK53). (B) Electron micrographs
of individual ring structures (top), rectangular structures (side), and
oblique view of same structures. (Scale bar, 50 nm.) (C)
Comparison of two different side views of the PrgH/K complex with NC
isolated from WT Salmonella. Note that the differences
seen in these structures are reflected in the differences seen in the
base structure of the NC. Scale bar, 50 nm. (D)
Schematic comparing the approximate size and shape of the isolated Prg
components: tetramer, 10 nm (n = 25); rectangular
(side), width 21 nm, height 9 nm (n = 27); ring
(top), outer diameter 21 nm, inner diameter 12 nm
(n = 30).