VIRULENCE-ASSOCIATED FYUA IRP2 GENE-CLUSTER OF YERSINIA-ENTEROCOLITICA BIOTYPE 1B CARRIES A NOVEL INSERTION-SEQUENCE IS1328/

The fyuA / irp2 gene cluster, which is part of the Yersinia pestis pig mentation (pgm) locus encoding genes involved in iron uptake and virul ence, is present in all pesticin-sensitive bacteria. In Y. enterocolit ica biotype 1B strains (serotypes 08, 020, 021), the fyuA / irp2 gene cluster carries an insertion of a novel repetitive sequence, IS1328. I t was also found in the genome of Y. enterocolitica 05 (biotype 1A) an d 013 (biotype 1B), but not in pesticin-sensitive Y. pseudotuberculosi s 01 and Escherichia coli Phi. The 1353-bp repetitive dement has 12-bp perfect inverted terminal repeats. A single open reading frame is cap able of encoding a 334-amino acid polypeptide. IS1328 DNA has high hom ology with the DNA sequences located downstream of the aggR gene from the enteroaggregative E. coli (EAggEC), to the region of the R751 plas mid flanking Tn501, to the sequence following the merR gene of 8. marc escens pDU1358 plasmid, and to the sequences of K. pneumoniae plasmid pCFF04. The putative polypeptide has 36.4% identity with the transposa se encoded by the Coxiella burnetii IS1111a insertion sequence. The IS 1328 insertion sequence could be responsible for the deletions of the fyuA / irp2 gene duster observed in Y. enterocolitica 08 and could rep resent a member of a new group of widely distributed repetitive elemen ts.