Introduction

When cells are exposed to high temperature, the synthesis of a small number of proteins known as heat-shock proteins (Hsp) becomes selective and rapid (, ). This process is called heat shock process. First found in Drosophila in 1960s, heat shock has been found in all the species that have been studied so far (, ) and it was suggested that heat shock response may have evolved before the divergence of pro-and eukaryotes (, ). The function of Hsps has also been extended from heat shock to other stress response, protein translocation, signal transduction, programmed cell death and ribosome assembly (maki2002). It is also found to be one of the most conserved gene regulatory systems that respond to environmental stresses. The total sum of heat shock proteins accounts for more than 3% in vivo cell protein mass at 37c (, ).Hsp70 protein (DnaK) is maybe the most conserved protein in biology with a nearly 5 % homology between eukaryotes and bacteria DnaK gene (, ). Its ubiquitous suggests heat shock may play a general role in guarding against cell damage (, ).

About 20 molecule species have been identified in prokaryotes heat shock (, ),(, ), most of which have homologous in eukaryotes. DnaK (the Hsp70 homologue of Escherichia coli ), DnaJ ( an eukaryotes Hsp40 homologue ), GrpE and FtsH have been proved to be major heat shock proteins to protect bacterial against heat shock. rpoH (previously also known as htpR or hin gene, product $\sigma ^{32}$, an alternative RNA polymerase $\sigma$ subunit (, ) was found to be the global regulator of heat shock gene expression in E.coli (, ), (, ).

Decades of studies in bacterial heat shock response has generated enough data to study this complex process numerically, which enables us to ask questions of the sensitivity, robust and limitation of this system.