De Mot R, Laeremans T, Schoofs G, Vanderleyden J
F. A. Janssens Laboratory of Genetics, Catholic University of Leuven, Heverlee, Belgium.
J Gen Microbiol. 1993 Jan;139(1):49-57. doi: 10.1099/00221287-139-1-49.
The recA gene of Pseudomonas fluorescens OE 28.3 was isolated by complementation of the Fec- phenotype of recombinant lambda EMBL3 phages in a RecA- Escherichia coli strain. The subcloned recA restored resistance to UV and methyl methanesulphonate (MMS) exposure in recA mutants of E. coli. DNA sequence analysis showed that the coding region of the P. fluorescens gene, specifying a protein of 352 amino acid residues, was preceded by an SOS box highly similar to those of Pseudomonas aeruginosa and Azotobacter vinelandii. The deduced amino acid sequence displayed highest homology to the RecA proteins from P. aeruginosa (87.8% identity) and A. vinelandii (84.3% identity). In both the regulatory region and the structural gene, a relatively high degree of sequence divergence from the Pseudomonas cepacia gene was observed. A mutant of P. fluorescens was constructed by inserting a kanamycin resistance cassette into its recA gene. This mutant exhibited an increased sensitivity to UV irradiation and MMS, and was strongly impaired in homologous recombinational activity.
通过在RecA⁻大肠杆菌菌株中对重组λEMBL3噬菌体的Fec⁻表型进行互补，分离出荧光假单胞菌OE 28.3的recA基因。亚克隆的recA恢复了大肠杆菌recA突变体对紫外线和甲磺酸甲酯（MMS）暴露的抗性。DNA序列分析表明，荧光假单胞菌基因的编码区指定了一个由352个氨基酸残基组成的蛋白质，其前面有一个与铜绿假单胞菌和棕色固氮菌的SOS框高度相似的SOS框。推导的氨基酸序列与铜绿假单胞菌（同一性为87.8%）和棕色固氮菌（同一性为84.3%）的RecA蛋白具有最高的同源性。在调控区和结构基因中，均观察到与洋葱伯克霍尔德菌基因存在较高程度的序列差异。通过将卡那霉素抗性盒插入荧光假单胞菌的recA基因构建了一个突变体。该突变体对紫外线照射和MMS表现出更高的敏感性，并且在同源重组活性方面受到严重损害。
