Heat shock transcription factor σ32 co-opts the signal recognition particle to regulate protein homeostasis in E. coli.
PLoS Biol
; 11(12): e1001735, 2013 Dec.
Article
en En
| MEDLINE
| ID: mdl-24358019
All cells must adapt to rapidly changing conditions. The heat shock response (HSR) is an intracellular signaling pathway that maintains proteostasis (protein folding homeostasis), a process critical for survival in all organisms exposed to heat stress or other conditions that alter the folding of the proteome. Yet despite decades of study, the circuitry described for responding to altered protein status in the best-studied bacterium, E. coli, does not faithfully recapitulate the range of cellular responses in response to this stress. Here, we report the discovery of the missing link. Surprisingly, we found that σ(32), the central transcription factor driving the HSR, must be localized to the membrane rather than dispersed in the cytoplasm as previously assumed. Genetic analyses indicate that σ(32) localization results from a protein targeting reaction facilitated by the signal recognition particle (SRP) and its receptor (SR), which together comprise a conserved protein targeting machine and mediate the cotranslational targeting of inner membrane proteins to the membrane. SRP interacts with σ(32) directly and transports it to the inner membrane. Our results show that σ(32) must be membrane-associated to be properly regulated in response to the protein folding status in the cell, explaining how the HSR integrates information from both the cytoplasm and bacterial cell membrane.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Factor sigma
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Partícula de Reconocimiento de Señal
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Proteínas de Escherichia coli
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Proteínas de Choque Térmico
Idioma:
En
Revista:
PLoS Biol
Asunto de la revista:
BIOLOGIA
Año:
2013
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos