THE LUX REGULON OF VIBRIO-FISCHERI ALLEVI ATES TYPE-I RESTRICTION IN ESCHERICHIA-COLI K12 CELLS

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