Description and characterization of IS994, a putative IS3 family insertionsequence from the salmon pathogen, Renibacterium salmoninarum

Renibacterium salmoninarum, a slowly growing, Gram-positive bacterium, is r esponsible for bacterial kidney disease in salmonid fishes world-wide. To d ate, no mobile genetic elements have been reported for this pathogen. Here, we describe the first insertion sequence (IS) identified from R salmoninar um. This element, IS994, has a significant predicted amino acid sequence ho mology (64.5 and 71.9%) to the two open reading frames encoding the transpo sase of IS6110 of Mycobacterium tuberculosis. Protein parsimony and protein distance matrix analyses show that IS994 is a member of group IS51 of the IS3 family. From a conservative estimate, there are at least 17 chromosomal insertions of IS994 or closely related elements. Sequence analysis of seve n of these loci reveals single nucleotide polymorphisms throughout the elem ent (including the terminal inverted repeats), a 15 bp insertion in three o f the seven loci, and an absence of flanking direct repeats or conserved in sertion site. Restriction fragment length polymorphism analysis of XbaI-dig ested chromosomal DNA shows variations among European and North American is olates, indicating that IS994 may be a useful molecular marker for epizooti ological studies. Published by Elsevier Science B.V. All rights reserved.