[Sequencing and comparative analysis of the lux operon of Photorhabdus luminescens strain ZM1: ERIC elements as putative recombination spots].

The EcoRI chromosomal fragment (6782 bp) containing the lux operon of Photorhabdus luminescens was cloned in pUC18 and completely sequenced. Enteric repetitive intergenic consensus (ERIC), an imperfect palindrome (125-127 bp) characteristics for Enterobacteriaceae genomes, was found in three sites. Strain Zm1 proved to differ in ERIC number and location from strains Hb, Hm, and Hw. Nucleotide substitution analysis showed that luxC and luxB, which are more than 1 kb away from ERIC, are similar to the corresponding Hb genes, whereas luxD, luxA, and luxE, which are close to ERIC, are intermediate between their Hb and Hw counterparts. The Hb/Hw nucleotide substitution ratio was 1:1 in regions adjacent to ERIC. Hence ERIC were assumed to play a role of recombination hot spots in the bacterial genome.