Phase-contrast-immunofluorescence analysis of HMW1 localization in wild-type M. pneumoniae (A) and mutant M6 producing HMW1 Δ1-4 (B), HMW1 Δ4 (C), HMW1 Δ1 (D), or reHMW1 (E). For each pair, the merged immunofluorescence and phase-contrast images are shown on the left and the corresponding immunofluorescence images alone are shown on the right. Bar, 2.0 μm.