Lortie L A, Gagnon G, Frenette M
Département de biochimie (Sciences), Université Laval, Québec, Canada.
Plasmid. 1994 Jul;32(1):1-9. doi: 10.1006/plas.1994.1038.
An insertion sequence-like element, IS1139, was cloned and sequenced from Streptococcus salivarius ATCC 25975 chromosome. This insertion sequence-like element is 1168 bp long and is delimited by inverted repeats of 29 bp and by a duplicated sequence of 6 bp. This IS possesses an open reading frame that codes for a putative transposase of 339 amino acids which has, respectively, 94, 35, 33, and 30% amino-acid identity with the transposases of IS1161 from S. salivarius ATCC 25975, IS4351 from Bacteroides fragilis, IS30 from Escherichia coli, and IS1086 from Alcaligenes eutrophus. Sequence analysis revealed that these transposases may have evolved from a common ancestral gene. Southern hybridization of restriction endonuclease-digested genomic DNA from 21 strains of oral streptococci, using a probe specific to the transposase-encoding gene (tnpA), revealed that IS1139 is found in two strains of S. salivarius, ATCC 25975 and ATCC 13419, in eight and two copies, respectively.
从唾液链球菌ATCC 25975染色体中克隆并测序了一个类插入序列元件IS1139。这个类插入序列元件长度为1168 bp，由29 bp的反向重复序列和6 bp的重复序列界定。该插入序列拥有一个开放阅读框，编码一个339个氨基酸的假定转座酶，该转座酶与来自唾液链球菌ATCC 25975的IS1161、脆弱拟杆菌的IS4351、大肠杆菌的IS30以及嗜碱产碱菌的IS1086的转座酶分别具有94%、35%、33%和30%的氨基酸同一性。序列分析表明，这些转座酶可能由一个共同的祖先基因进化而来。使用转座酶编码基因（tnpA）特异性探针，对21株口腔链球菌经限制性内切酶消化的基因组DNA进行Southern杂交，结果显示在两株唾液链球菌ATCC 25975和ATCC 13419中发现了IS1139，分别有8个和2个拷贝。
