Abstract:

With the method of polymerase chain reaction and homologous genetic recombination in vivo, the gene encoding bacterial phytochrome in the non-photosynthetic and extremely radioresistant bacterium D.radiodurans was deleted from the genome. Survival rates of the mutant strain bphP^- obtained and wild type strain were investigated under different doses of T-radiation and hydrogen peroxide. The results indicated that the bphF strain were much more sensitive to hydrogen peroxide treatment comparing to that of wild type R1, while radioresistant activities of the mutant and the R1 strain exhibited at the same level. Experiments of D.radiodurans R1 strain to different light radiation revealed that intense white light radiation remarkably inhibited both the colony growth of wild-type and the phytochrome function-deficient mutant of D. radiodurans with no significant difference, while the growth of Escherichia coli K 12 was not affected under the same light condition. No remarkable effects of red and blue light on the growth of D.radiodurans strain were shown. Based on these results, phytochrome in D.radiodurans might primarily act as a signal transferrer and regulator of oxidant pressure.

Key words: Deinococcus radiodurans, phytochrome, light-inducing damage, oxygen sensor

摘要：

利用PCR和体内同源重组技术，对耐辐射奇球菌（Deinococcus radiodurans R1）中光敏色素基因诱导缺失突变，构建了突变株bphP^-。对突变株分别进行不同剂量电离辐射（IR）和不同浓度过氧化氢（H2O2）处理，并以野生株R1做对照。结果表明：与野生株相比，突变株bphP^-对过氧化氢的敏感性明显上升，而对电离辐射的抗性野生型基本不变。不同性质的光照试验显示，强白光对野生菌株和光敏色素突变的耐辐射奇球菌都具有显著的抑制菌落生长作用，两者差异不明显。红光和蓝光对野生株和突变株的生长都没有明显的抑制作用。强白光照射对没有光敏色素调控体系的大肠杆菌K12菌株抑制不明显。因此，耐辐射奇球菌中光敏色素可能主要是作为氧化环境信号传递和调控的蛋白。

关键词: 耐辐射奇球菌 光敏色素 光损伤 氧感受器