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℃ 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 heatshock 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℃,accumulation of the HSPs induced by BNTR1 could make cells much more tolerant than those without BNTR1 at 42℃.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.