Nucleotide sequence of a repetitive element isolated from Leptospira interrogans serovar hardjo type hardjo-bovis

Abstract

A repetitive element from the genome of Leptospira interrogans serovar hardjo type hardjo-bovis ('L. hardjo-bovis') was identified, cloned and sequenced. Similar sequences were shown by hybridization to be encoded by a further eight of 32 other leptospiral serovars tested. An undefined number of repetitive elements were located in the L. hardjo-bovis genome; sequence degeneracy of the elements was observed and no significant open reading frames were identified within the AT-rich (60%) 1467 bp repetitive element. The termini encoded a GC-rich 8 bp repeat motif and two variants showed rearrangements centred on these motifs. The nucleotide sequences of the chromosomal regions flanking the repetitive elements were determined but showed no similarities, with one exception which had a GAAC repeat directly adjacent to both termini. Similar hybridization patterns were shown by Southern transfers of L. hardjo-bovis total genomic digests probed with the repetitive element. Oligonucleotide primer pairs designed from sequences internal to the repetitive element and adjacent chromosomal regions were used in polymerase chain reaction experiments. With one primer pair all L. hurdjo-bovis isolates, but no other serovar, gave identical amplified products. Evidence that the repetitive element may have derived from an acquired insertion sequence that is now inactive and chromosomally fixed is discussed.

The IS 1111 Family Members IS 4321 and IS 5075 Have Subterminal Inverted Repeats and Target the Terminal Inverted Repeats of Tn 21 Family Transposons

“…For example, IS1533, which is found in multiple copies in the chromosome of several Leptospira species, has been grouped with IS1111 (3,15). IS1533 was one of the first IS110/IS1111 family members sequenced, and IR flanked on both sides by additional conserved residues were identified (38,39). Although in one example the N-terminal portion of the predicted transposase sequence showed similarities to the sequences of a group of IS110-related transposases, including IS1111 (39), the other predicted product was not the same, and both sequences appear to include multiple frameshifts in the transposase gene.…”

“…It was previously assumed that, by analogy with the majority of IS, the IR represent the termini, and similarities noted between the sequences flanking the IR for IS4321 and IS1328 (32) and for several IS belonging to the IS1111 group (15,38,39) were believed to indicate an element of target site specificity. As the terminal sequences could account for part of these regions, we sought evidence for their presence in additional IS.…”

IS1500, an IS3-like element from Leptospira interrogans

“…We hypothesized that recombination between like copies of repetitive DNA may be used to generate the rearrangements detected during physical mapping studies. R et al, 1992;Ralph & McClelland, 1993;Saint Girons e t al., 1992;Van Eys et al, 1988;Woodward & Sullivan, 1991 ;Zuerner, 1993Zuerner, , 1994Zuerner et al, 1993a, b). Studies of L. borgpetersenii provide insight into how ISlike elements contribute to the fluidity of the leptospiral genome.…”

“…Studies of L. borgpetersenii provide insight into how ISlike elements contribute to the fluidity of the leptospiral genome. An IS-like element, IS1533, has been isolated from L. borgpetersenii and characterized (Woodward & Sullivan, 1991 ;Zuerner & Bolin, 1988;Zuerner, 1994). This element belongs to the recently recognized IS170 family of transposable elements (Zuerner, 1994).…”

Two New Leptospiral Serovars in the Hebdomadis Serogroup Isolated from Zimbabwe Cattle

“…In addition, this method may delineate artificially closely related strains on the one hand while it fails to distinguish genetically different but antigenically similar strains In an effort to replace the serological classification system with a natural subspecies classification system based on phylogenetically determined relationships, a variety of modern methods for genetic analysis have been introduced. These methods include chromosomal DNA restriction fragment length polymorphism (RFLP) analysis (6, 10, 11, 13,25,36), DNA hybridization with total DNA probes (26,27,35), restriction analysis by Southern blotting with recombinant DNA probes (24,28,37,41,43,44), restriction analysis of chromosomal DNA by pulsed-field gel electrophoresis (PFGE) (14-16), rRNA gene RFLP analysis (17, 19,29,30), and PCR fingerprinting (la, 2, 12, 18, 31, 32). Although useful, these methods have so far failed to produce a coherent picture which allows researchers to develop a natural and logical classification system based on genetic traits.…”