Dynamic Localization of MreB in Vibrio parahaemolyticus and in the Ectopic Host Bacterium Escherichia coli

Abstract

ABSTRACT MreB, a homolog of eukaryotic actin, participates in morphogenesis, cell division, cell polarity, and chromosome segregation in prokaryotes. In this study, a yellow fluorescent protein conjugate (YFP-MreB Vp ) was generated to investigate the behavior of MreB in merodiploid strain SC9 of the enteropathogen Vibrio parahaemolyticus . Under normal growth conditions, YFP-MreB Vp formed helical filaments with a pitch of 0.64 ± 0.09 μm in about 85% of exponential-phase cells, and different clusters, relaxed coils, and ring configurations were observed in a small proportion of the cells. Overexpression of YFP-MreB Vp substantially altered the structure of the MreB cytoskeleton and resulted in swollen and pleomorphic cells. Disturbing the activities of penicillin-binding proteins or adding magnesium suppressed the morphological distortions. These results indicate that mislocalization of cell wall-synthesizing machinery was responsible for morphological abnormality. By expressing YFP-MreB Vp in the ectopic host bacterium Escherichia coli , shrinkage, fragmentation, and annealing of MreB Vp filaments were directly observed. This work revealed the dynamic pattern of the localization of YFP-MreB Vp in V. parahaemolyticus and its relationship to cell morphogenesis, and the YFP-MreB Vp - E. coli system may be used to investigate the dynamic spatial structures of the MreB cytoskeleton in vivo.