Qiu Xiaoyun, Daly Michael J, Vasilenko Alexander, Omelchenko Marina V, Gaidamakova Elena K, Wu Liyou, Zhou Jizhong, Sundin George W, Tiedje James M
Center for Microbial Ecology, PSSB 540, Michigan State University, East Lansing, MI 48824, USA.
J Bacteriol. 2006 Feb;188(3):1199-204. doi: 10.1128/JB.188.3.1199-1204.2006.
The ionizing radiation (IR) dose that yields 20% survival (D20) of Shewanella oneidensis MR-1 is lower by factors of 20 and 200 than those for Escherichia coli and Deinococcus radiodurans, respectively. Transcriptome analysis was used to identify the genes of MR-1 responding to 40 Gy (D20). We observed the induction of 170 genes and repression of 87 genes in MR-1 during a 1-h recovery period after irradiation. The genomic response of MR-1 to IR is very similar to its response to UV radiation (254 nm), which included induction of systems involved in DNA repair and prophage synthesis and the absence of differential regulation of tricarboxylic acid cycle activity, which occurs in IR-irradiated D. radiodurans. Furthermore, strong induction of genes encoding antioxidant enzymes in MR-1 was observed. DNA damage may not be the principal cause of high sensitivity to IR, considering that MR-1 carries genes encoding a complex set of DNA repair systems and 40 Gy IR induces less than one double-strand break in its genome. Instead, a combination of oxidative stress, protein damage, and prophage-mediated cell lysis during irradiation and recovery might underlie this organism's great sensitivity to IR.
导致希瓦氏菌MR-1存活率为20%（D20）的电离辐射（IR）剂量分别比大肠杆菌和耐辐射球菌低20倍和200倍。转录组分析用于鉴定MR-1中对40 Gy（D20）产生响应的基因。我们观察到，在照射后的1小时恢复期内，MR-1中有170个基因被诱导，87个基因被抑制。MR-1对IR的基因组反应与其对紫外线辐射（254 nm）的反应非常相似，其中包括参与DNA修复和原噬菌体合成的系统的诱导，以及三羧酸循环活性不存在差异调节，而这种差异调节在IR照射的耐辐射球菌中会出现。此外，还观察到MR-1中编码抗氧化酶的基因被强烈诱导。考虑到MR-1携带编码一套复杂DNA修复系统的基因，并且40 Gy的IR在其基因组中诱导的双链断裂少于一个，可以认为DNA损伤可能不是其对IR高度敏感的主要原因。相反，在照射和恢复过程中，氧化应激、蛋白质损伤和原噬菌体介导的细胞裂解共同作用，可能是该生物体对IR高度敏感的原因。
