[Lux-regulon from Vibrio fisheri reduces type 1 restriction in Escherichia coli K12 cells].

The EcoK restriction of nonmodified phage lambda.0 controlled by Escherichia coli K12 lon- cells is alleviated 10-20-fold in the presence of a hybrid plasmid containing the entire lux regulon of Vibrio fischeri. The La protease participates in degradation of the regulatory LuxR-LuxI proteins; therefore, transcription of the right lux operon begins significantly earlier than in the lon+ bacteria and is characterized by high content of the N-(3-oxohexanoyl) homoserine lactone autoinducer in medium. The effect of lux-induced alleviation of type I restriction in the lon mutants of E.coli K12 is proposed to depend on the reduction at the intracellular level of S-adenosylmethionine, one of the LuxI synthase substrates responsible for autoinducer synthesis.