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Acta Biochim Biophys Sin (Shanghai). 2017 Mar 1;49(3):262-269. doi: 10.1093/abbs/gmx004.

An E3 ubiquitin ligase from Brassica napus induces a typical heat-shock response in its own way in Escherichia coli.

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Key Laboratory of Bio-resources and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, China.
CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610064, China.


Previously, we have identified a novel E3 ubiquitin ligase, BNTR1, which plays a key role in heat stress response in Brassica napus. In this study, we accidentally found that BNTR1 can also improve thermal tolerance and reduce growth inhibition at 42°C in Escherichia coli, in a manner different from that in plant. We show that BNTR1 activates E. coli heat-shock response at low concentration in soluble form instead of in inclusion body, but BNTR1 is not functioning as a heat-shock protein (HSP) because deficient temperature-sensitive mutants of HSP genes display unconspicuous thermal tolerance in the presence of BNTR1. Our further studies show that BNTR1 triggers heat-shock response by competing with σ32 (σ32, heat-shock transcription factor) to its binding proteins DnaJ (HSP40) and DnaK (HSP70), which results in the release and accumulation of σ32, thereby promoting the heat-shock response, even under the non-heat-shock conditions. At 37°C, accumulation of the HSPs induced by BNTR1 could make cells much more tolerant than those without BNTR1 at 42°C. Thus, our results suggest that BNTR1 may potentially be a promising target in fermentation industry for reducing impact from temperature fluctuation, where E. coli works as bioreactors.


E3 ubiquitin ligase; heat-shock response; thermal resistance; σ32

[Indexed for MEDLINE]

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