Localization of DnaK (chaperone 70) from Escherichia coli in an osmotic-shock-sensitive compartment of the cytoplasm.
The chaperone DnaK can be released (up to 40%) by osmotic shock, a procedure which is known to release the periplasmic proteins and a select group of cytoplasmic proteins (including thioredoxin and elongation factor Tu) possibly associated with the inner face of the inner membrane. As distinct from periplasmic proteins, DnaK is retained within spheroplasts prepared with lysozyme and EDTA. The ability to isolate DnaK with a membrane fraction prepared under gentle lysis conditions supports a peripheral association between DnaK and the cytoplasmic membrane. Furthermore, heat shock transiently increases the localization of DnaK in the osmotic-shock-sensitive compartment of the cytoplasm. We conclude that DnaK belongs to the select group of cytoplasmic proteins released by osmotic shock, which are possibly located at Bayer adhesion sites, where the inner and outer membranes are contiguous.
el Yaagoubi
A
A
Biochimie Génètique, Institut Jacques Monod, Université Paris 7, Paris, France.
Kohiyama
M
M
Richarme
G
G
D002451:Cell Compartmentation; D003593:Cytoplasm / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins / Q000302:isolation & purification*; D015636:Magnesium Chloride / Q000494:pharmacology; D018832:Molecular Chaperones; D009997:Osmotic Pressure; D013104:Spheroplasts / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D015636:Magnesium Chloride; C063842:dnaK protein, E coli