Abstract: σ factor, a subunit of RNA polymerase in prokaryotes, can activate transcriptional initiation through a kind of reversible bind with the active catalytic sites of RNA polymerase core enzyme，promote the accurate identification of RNA polymerase to transcriptional initiation site and eventually activate the expression of corresponding genes specifically. With the strong capacity and environmental adaptability to radiation, oxidation and high temperature，Deinococcus radiodurans（D. radiodurans）contains three σ factors，among which Sig2 may function significantly in its strong environmental suitability. In this study，we developed the sig2 deletion mutant strain，named Δsig2, results showed that Δsig2 were more sensitive to heat and had significantly lower survivability than control group D. radiodurans wild type under the condition of high temperature（48℃）stress. We also analyzed the QRT-PCR results and verify that the deletion of sig2 contributed to positive or negative regulation of heat stress related genes in a degree. As a result，we speculated sig2 probably involved in the regulation of heat stress response.

Key words: Deinococcus radiodurans, &sigma, factor, Sig2, high temperature stress

摘要： σ因子是原核生物RNA聚合酶的一个亚基，能可逆地结合于RNA聚合酶核心酶的活性催化位点，促进RNA聚合酶正确识别转录起始位点，特异地激活相应基因的表达。耐辐射异常球菌具有极强的抗极端辐射氧化和高温的能力及环境适应性，它含有3个σ因子，其中Sig2可能在该菌环境适应性上发挥着重要作用。构建了耐辐射异常球菌sig2基因的缺失突变株Δsig2，通过48℃高温胁迫冲击实验发现Δsig2对热具有极强的敏感性，相对于对照菌株DR野生型生存能力明显下降；实时荧光定量PCR发现，sig2基因的缺失导致热胁迫相关基因发生不同程度的上调或下调，从而推测sig2基因参与了热胁迫反应的调控。

关键词: 耐辐射异常球菌；&sigma, 因子；Sig2；高温胁迫