FIG. 6.

SurA is required for IBC maturation. UTI89/pcomGFP, UTI89/pcomGFP surA::kan, and UTI89/pDH15 surA::kan were used to inoculate C3H/HeN female mice, and the bladders were viewed in whole mount by confocal microscopy at 6 h (top row) and 16 h (bottom row). UTI89 forms early IBCs at 6 h (A) and matures into tightly packed coccoid IBCs by 16 h (D), while the UTI89 surA mutant fails to establish intracellular growth (B). At 16 h, a single collection of ∼20 intracellular bacteria was seen in one of >20 bladders infected with UTI89 surA::kan across several replicated experiments (E). Complementation of type 1 piliation in vitro and binding and invasion in vivo via the plasmid pDH15 permit invasion and modest intracellular replication by 6 h (C), but UTI89/pDH15 surA::kan IBCs do not mature properly by 16 h (F), demonstrating lower density, looser organization, and persistent rod-shaped bacterial morphology compared to wild-type IBCs.