Characterization of the heat shock response inEnterococcus faecalis

Abstract

We have characterized the general properties of the heat shock response of the Gram-positive hardy bacterium Enterococcus faecalis. The heat resistance (60 degrees C or 62.5 degrees C, 30 min) of log phase cells of E. faecalis grown at 37 degrees C was enhanced by exposing cells to a prior heat shock at 45 degrees C or 50 degrees C for 30 min. These conditioning temperatures also induced ethanol (22%, v/v) tolerance. The onset of thermotolerance was accompanied by the synthesis of a number of heat shock proteins. The most prominent bands had molecular weights in the range of 48 to 94kDa. By Western blot analysis two of them were found to be immunologically related to the well known DnaK (72kDa) and GroEL (63kDa) heat shock proteins of Escherichia coli. Four other proteins showing little or no variations after exposure to heat are related to DnaJ, GrpE and Lon (La) E. coli proteins and to the Bacillus subtilis sigma 43 factor. Ethanol (2% or 4%, v/v) treatments elicited a similar response although there was a weaker induction of heat shock proteins than with heat shock.

Two-Dimensional Electrophoresis Study of Lactobacillus delbrueckii subsp. bulgaricus Thermotolerance

“…bulgaricus cell death was reported, the elapsed time corresponding to 4 min of challenge (33). Even when the tests were longer, as described for Enterococcus faecalis and Rhodothermus obamensis (30 and 60 min, respectively), the curves always showed a constant decrease in cell viability (1,31).…”

Differentiation between cold shock proteins and cold acclimation proteins in a mesophilic gram-positive bacterium, Enterococcus faecalis JH2-2

“…Enterococcus faecalis is interesting for its ability to resist numerous stresses (4,8,10). It is an allochthonous, grampositive bacterium (31) which lives in the intestinal tracts of many animals and is commonly present in cold biological environments (3,29,32).…”

Identification and Characterization of gsp65 , an Organic Hydroperoxide Resistance ( ohr ) Gene Encoding a General Stress Protein in Enterococcus faecalis

“…Moreover, starvation promoted by exhaustion of the carbon and energy source glucose, and after incubation in an oligotrophic microcosm, strongly enhances the resistance of E. faecalis to environmental stresses and can be correlated with an increased synthesis of many proteins (11,12,15). The adaptation phenomenon has also been observed when exponentially growing cultures of E. faecalis are subjected to sublethal conditions, e.g., 30 min at 50 or 37°C in the presence of hydrogen peroxide (2.4 mM), sodium dodecyl sulfate (SDS) (0.01%), bile salts (0.08%), cadmium chloride (50 g/ml), or pH 4.8 or 10.5 (2,(4)(5)(6)(7)(8)(9)(10)17). Under these conditions, E. faecalis developed phenotypic resistances towards usually lethal stresses (heating at 62°C, pH 3.2 or 11.9, 45 mM H 2 O 2 , CdCl 2 [50 mg/ml], SDS [0.017%], or bile salts [0.3%]).…”