Sequence analysis and distribution in Salmonella enterica serovars of IS3-like elements

The genome of Salmonella enterica serovar Enteritidis was shown to possess three IS3-like insertion elements, designated IS1230A, B and C, and each wa s cloned and their respective deoxynucleotide sequences determined. Mutatio ns in elements IS1230A and B resulted in frameshifts in the open reading fr ames that encoded a putative transposase to be inactive. IS1230C was trunca ted at nucleotide 774 relative to IS1230B and therefore did not possess the 3' terminal inverted repeat. The three IS1230 derivatives were closely rel ated to each other based on nucleotide sequence similarity. IS1230A was loc ated adjacent to the sef operon encoding SEF14 fimbriae located at minute 9 7 of the genome of S. Enteritidis. IS1230B was located adjacent to the umuD C operon at minute 42.5 on the genome, itself located near to one terminus of an 815-kb genome inversion of S. Enteritidis relative to S. Typhimurium. IS1230C was located next to attB, the bacteriophage P22 attachment site, a nd proB, encoding gamma-glutamyl phosphate reductase. A truncated 3' remnan t of IS1230, designated IS1230T, was identified in a clinical isolate of S. Typhimurium DT193 strain 2391. This element was located next to attB adjac ent to which were bacteriophage P22-like sequences. Southern hybridisation of total genomic DNA from eighteen phage types of S. Enteritidis and eighte en definitive types of S. Typhimurium showed similar, if not identical, res triction fragment profiles in the respective serovars when probed with IS12 30A.