Abstract：The genomic DNA was extracted from Pseudomonas aeruginosa strain PAO1,and the coding sequence of LexA protein was amplified and linked to vector pMD-18T.The recombinant plasmid was digested with NcoI and XhoI;and the fragment with size of 650 bps was recovered and subcloned into the expression vector pET-28a(+).Then,the recombinant plasmid was transformed to E.coli BL21.After being sequenced,the expressed product was identified with SDS-PAGE by one step method of Ni-pearls absorption,and this protein was transferred to PVDF membrane then sequencing at N-terminus by Edman's degradation method.The experimental results showed that the LexA protein of P.aeruginosa could be expressed in E.coli,and after purification,the N-terminus sequencing analysis proved that the expressed product was the LexA protein of PAO1 and its purification rate could reach up to 96%.It is concluded that this work provides a basis for the identification of SOS box and LexA regulated gene in the genome of P.aeruginosa strain PAO1.
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