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When isogenic strains of Escherichia coli, RR1 (rec+) and HB101 (recA), were transformed with mapped recombinant plasmids known to contain Vibrio harveyi luciferase genes and large regions of DNA flanking on both sides, a small percentage (0.005%) of the colonies expressed high levels of luminescence (up to 10(12) quanta s-1 ml-1) in the absence of added aldehyde. The altered ability to express light was found to be due to a mutation in the host and not to an alteration in the recombinant DNA. When these bright colonies were cured of plasmid, they could be retransformed with cloned V. harveyi gene fragments in cis and in trans to yield luminescent colonies at 100% frequency. The maximum length of V. harveyi DNA required to produce light-emitting E. coli was shorter (6.3 kilobase pairs) than that required for expression of the V. fischeri system in E. coli. Cell extracts from bright clones contained wild-type levels of activity for the heteropolymeric (alpha beta) luciferase; fatty acid labeling revealed the presence of the three acylated polypeptides of the fatty acid reductase system which is involved in aldehyde biosynthesis for the luminescence reaction. The increased light emission in the mutant bacteria appeared to arise in part from production of higher levels of polycistronic mRNAs coding for luciferase.
Miyamoto et al. (Thu,) studied this question.