Sedgwick S G, Yarranton G T, Heath R W
Mol Gen Genet. 1981;184(3):457-9. doi: 10.1007/BF00352522.
UV irradiation of lexA3 mutants of E. coli caused lysogenic induction of prophage lambda, lambda i21, lambda i434 and phi 80. Maximal induction in lexA3 lysogens needed less UV than in lexA+ bacteria and gave 25-100% of the normal levels of infective centres induced. Assays of gene expression arising from derepression of a defective lambda prophage showed at least 40% of the normal levels of induction by mitomycin C in lexA3 bacteria. The need for post-irradiation protein synthesis for lysogenic induction in lexA3 lysogens was reduced by increasing the basal level of recA protein with a recA+ plasmid. It is concluded that in lexA E. coli some recA protein synthesis, too small to be detected by physical means, is needed for UV induced lysogenic induction.
紫外线照射大肠杆菌的lexA3突变体可导致原噬菌体λ、λi21、λi434和φ80的溶原菌诱导。与lexA+细菌相比，lexA3溶原菌中实现最大诱导所需的紫外线剂量更少，且诱导产生的感染中心水平达到正常水平的25%-100%。对缺陷型λ原噬菌体去阻遏后产生的基因表达进行检测，结果显示lexA3细菌中丝裂霉素C诱导产生的正常水平至少为40%。通过用recA+质粒提高recA蛋白的基础水平，可减少lexA3溶原菌溶原菌诱导中对照射后蛋白质合成的需求。得出的结论是，在lexA大肠杆菌中，紫外线诱导的溶原菌诱导需要一些recA蛋白合成，其数量少到无法通过物理手段检测到。
