RT Journal Article SR Electronic(1) A1 Sugimoto, Shinya A1 Saruwatari, Kozue A1 Higashi, Chihana A1 Sonomoto, KenjiYR 2008 T1 The proper ratio of GrpE to DnaK is important for protein quality control by the DnaK–DnaJ–GrpE chaperone system and for cell division JF Microbiology, VO 154 IS 7 SP 1876 OP 1885 DO https://doi.org/10.1099/mic.0.2008/017376-0 PB Microbiology Society, SN 1465-2080, AB A balance of the intracellular concentrations of molecular chaperones in response to environmental conditions is of considerable importance for cellular homeostasis. Here, the physiological consequences of overexpression of GrpE in wild-type Escherichia coli MC4100 were examined. Overexpression of GrpE resulted in defects in cell division and growth, but overexpression of GrpE-G122D, which carries the G122D point mutation resulting in impaired interaction with DnaK, did not; this indicated that the effect of GrpE overexpression could be related to the DnaK chaperone function. Phase-contrast and fluorescence micrographs suggested that the N-terminal GFP-fused GrpE was colocalized with DnaK on the surface of inclusion bodies. An in vitro luciferase-refolding activity assay using purified DnaK, DnaJ and GrpE proteins demonstrated that high concentrations of GrpE significantly inhibited DnaK-mediated refolding. Furthermore, cell-free extracts from wild-type cells and GrpE-G122D-overexpressing cells significantly enhanced the refolding of luciferase. In the GrpE-overexpressing cells, abnormal localization of the cell-division protein FtsZ was observed by indirect immunofluorescence microscopy. In conclusion, the overexpression of GrpE caused a defect in the functionality of the DnaK chaperone system; this would result in filamentous morphology via abnormalities in the cell-division machinery., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.2008/017376-0