Cloning and expression of the lux operon of Photorhabdus luminescens, strain ZM1: the nucleotide sequence of luxAB genes and basic characteristics ofluciferase

A chromosomal fragment of bacteria Photorhabdus luminescens Zm1, which cont ains the Iue operon, was cloned into the vector pUC18. The hybrid clone con taining plasmid pXen7 with the EcoRI fragment approximately 7-kb was shown to manifest a high level of bioluminescence. By subcloning and restriction analysis of the EcoRI fragment, the location of luxCDABE genes relative to restriction sites was determined. The nucleotide sequence of the DNA fragme nt containing the luxA and luxB genes encoding alpha- and beta-subunits of luciferase was determined. A comparison with the nucleotide sequences of lu xAB genes in Hm and Hw strains of Ph. luminescens revealed 94.5 and 89.7% h omology, respectively. The enterobacterial repetitive intergenic sequence ( ERIC) of 126 bp typical for Hw strains was identified in the spacer between the luxD and luxA genes. The lux operon of Zm1 is assumed to emerge throug h recombination between Hm and Hw strains. Luciferase of Ph. luminescens wa s shown to possess a high thermal stability: its activity decreased by a fa ctor of 10 at 44 degrees C for 30 min, whereas luciferases of marine bacter ia Vibrio fischeri and Vibrio harveyi were inactivated by one order of magn itude at 44 degrees C for 1 and 6 min, respectively. The lux genes of Ph. l uminescens are suggested for use in gene engineering and biotechnology.