Woodward M J, Sullivan G J
Molecular Genetics Unit, Central Veterinary Laboratory, Weybridge, Surrey, UK.
J Gen Microbiol. 1991 May;137(5):1101-9. doi: 10.1099/00221287-137-5-1101.
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. hardjo-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.
从问号钩端螺旋体血清型哈德焦波氏亚种（“哈德焦波氏钩端螺旋体”）基因组中鉴定出一个重复元件，进行了克隆和测序。通过杂交表明，在所测试的其他32种钩端螺旋体血清型中的另外8种也编码相似序列。在哈德焦波氏钩端螺旋体基因组中定位了数量不定的重复元件；观察到这些元件的序列简并性，并且在富含AT（60%）的1467 bp重复元件内未鉴定到明显的开放阅读框。其末端编码一个富含GC的8 bp重复基序，两个变体显示以这些基序为中心的重排。确定了重复元件两侧染色体区域的核苷酸序列，但未显示出相似性，但有一个例外，其在两个末端直接相邻处有GAAC重复序列。用该重复元件探测哈德焦波氏钩端螺旋体全基因组消化产物进行Southern转移，显示出相似的杂交模式。从重复元件内部和相邻染色体区域的序列设计的寡核苷酸引物对用于聚合酶链反应实验。使用一对引物，所有哈德焦波氏钩端螺旋体分离株均产生相同的扩增产物，但其他血清型则无此现象。文中讨论了该重复元件可能源自一个现已失活并固定在染色体上的获得性插入序列的证据。
