Heat-resistance and heat-shock response in the nosocomial pathogen Enterococcus faecium.
We have characterized the heat-shock response of the nosocomial pathogen Enterococcus faecium. The growth of E. faecium cells was analyzed at different temperatures; little growth was observed at 50 degrees C, and no growth at 52 degrees C or 55 degrees C. In agreement, a marked decrease of general protein synthesis was observed at 52 degrees C, and very light synthesis was detected at 55 degrees C. The heat resistance of E. faecium cells was analyzed by measuring the survival at temperatures higher than 52 degrees C and, after 2 h of incubation, viable cells were still observed at 70 degrees C. By Western blot analysis, two heat-induced proteins were identified as GroEL (65 kDa) and DnaK (75 kDa). Only one isoform for either GroEL or DnaK was found. The gene expression of these heat-shock proteins was also analyzed by pulsed-labeled experiments. The heat-induced proteins showed an increased rate of synthesis during the first 5 min, reaching the highest level of induction after 10 min and returning to the steady-state level after 20 min of heat treatment.
Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, CCS, Bloco I, Cidade Universitária 21491-590, Rio de Janeiro, RJ, Brazil.
Marinella
M
Silva Laport
Marilene Ramos
MR
da Silva
Carla
C
Costa Silva
Maria
M
do Carmo de Freire Bastos
Marcia
M
Giambiagi-deMarval
D018834:Chaperonin 60 / Q000378:metabolism; D003428:Cross Infection / Q000382:microbiology*; D003470:Culture Media; D016984:Enterococcus faecium / Q000254:growth & development* / Q000502:physiology; D029968:Escherichia coli Proteins; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D018869:Heat-Shock Response; D006358:Hot Temperature; D006801:Humans
D018834:Chaperonin 60; D003470:Culture Media; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C063842:dnaK protein, E coli