title: Cardiolipin promotes polar localization of osmosensory transporter ProP in Escherichia coli.
abstract: The osmolality required to activate osmosensory transporter ProP and the proportion of cardiolipin (CL) among the phospholipids of Escherichia coli rise with growth medium osmolality. Most CL synthesis has been attributed to the cls gene product. Transcription of cls increased with osmolality. The proportion of CL was low and osmolality-independent in cls(-) bacteria. It increased more dramatically on the transition to stationary phase in cls(-) than cls(+) bacteria. Thus, Cls is responsible for osmoregulated CL synthesis and other enzymes may contribute to CL accumulation during stationary phase. The proportion of phosphatidylglycerol (PG) was elevated and it increased with medium osmolality in cls(-) bacteria. A cls defect impaired growth of E. coli on solid and in liquid media at low and, more strongly, at high osmolality. Bacteria cultured at high osmolality without osmoprotectant were shorter and rounder than those cultured at low osmolality or with glycine betaine. Fluorescence microscopy showed that CL and ProP colocalize at the poles and near the septa of dividing E. coli cells. The polar localization of ProP was independent of its expression level but correlated with the proportion and polar localization of CL. Association with CL (and not PG) may be required for polar ProP localization.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Tatyana
authors.initials: T
authors.lastname: Romantsov
authors.forename: Stephan
authors.initials: S
authors.lastname: Helbig
authors.forename: Doreen E
authors.initials: DE
authors.lastname: Culham
authors.forename: Chad
authors.initials: C
authors.lastname: Gill
authors.forename: Leanne
authors.initials: L
authors.lastname: Stalker
authors.forename: Janet M
authors.initials: JM
authors.lastname: Wood
mesh_terms: D002308:Cardiolipins / Q000096:biosynthesis* / Q000378:metabolism; D016764:Cell Polarity; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009994:Osmolar Concentration; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism
chemical_list: D002308:Cardiolipins; D003470:Culture Media; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C079244:ProP protein, E coli; D027981:Symporters; D017855:Transferases (Other Substituted Phosphate Groups); C100091:cardiolipin synthetase