High temperature stress resistance of Escherichia coli induced by a tobacco class I low molecular weight heat-shock protein

TLHS1 is a class I low molecular weight heat-shock protein (LMW HSP) of tob acco (Nicotiana tabacum). For a functional study of TLHS1, a recombinant DN A coding for TLHS1 with a hexahistidine tag at the amino-terminus,ras const ructed and expressed in Escherichia coli. An expressed fusion protein, H(6) TLHS1, was purified using a Ni2+ affinity column and a Sephacryl S400 HR co lumn, A polyclonal antibody against H(6)TLHS1 was produced to follow the fa te of H(6)TLHS1 in E, coli, The fusion protein in E, coli maintained its so lubility at a temperature of up to 90 degreesC and most of the proteins in the E. coli cell lysate with H(6)TLHS1 were prevented from thermally induce d aggregation at up to 90 degreesC, We compared the, viability of E. coli c ells expressing H(6)TLHS1 to the E, coli cells without H(6)TLHS1 at a tempe rature of 50 degreesC. After 8 h of high temperature treatment, E, coli cel ls with H(6)TLHS1 survived about three thousand times more than the bacteri al cells without H(6)TLHS1. These results showed that a plant class I LMW H SP, TLHS1, can protect proteins of E. coli from heat denaturation, which co uld lead to a higher survival rate of the bacterial cells at high temperatu re.