Heat-Resistance and Heat-Shock Response in the Nosocomial Pathogen <Emphasis Type="Italic">Enterococcus faecium</Emphasis> |
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Authors: | Marinella Silva Laport Marilene Ramos da Silva Carla Costa Silva Maria do Carmo de Freire Bastos Marcia Giambiagi-deMarval |
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Institution: | (1) 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, BR |
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Abstract: | 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°C, and no growth at 52°C or 55°C. In agreement,
a marked decrease of general protein synthesis was observed at 52°C, and very light synthesis was detected at 55°C. The heat
resistance of E. faecium cells was analyzed by measuring the survival at temperatures higher than 52°C and, after 2 h of incubation, viable cells
were still observed at 70°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.
Received: 29 March 2002 / Accepted: 5 July 2002 |
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