LINEAR PLASMIDS OF BORRELIA-BURGDORFERI HAVE A TELOMERIC STRUCTURE AND SEQUENCE SIMILAR TO THOSE OF A EUKARYOTIC VIRUS
LINEAR PLASMIDS OF BORRELIA-BURGDORFERI HAVE A TELOMERIC STRUCTURE AND SEQUENCE SIMILAR TO THOSE OF A EUKARYOTIC VIRUS
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DOI：
10.1128/jb.173.22.7233-7239.1991
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发表时间：
1991-11-01
影响因子：
3.2
通讯作者：
BARBOUR, AG
中科院分区：
文献类型：
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作者：
HINNEBUSCH, J;BARBOUR, AG
疏螺旋体属的螺旋体具有双链线性质粒，末端共价封闭。测定了莱姆病病原体伯氏疏螺旋体B31株16 kb线性质粒末端连接的物理性质。分离了代表该质粒左右两端的原生端粒片段，并进行了Maxam-Gilbert序列分析。在质粒末端，两条DNA链形成了一个不间断的、完全回文的、富含At的序列。该伯氏疏螺旋体线性质粒由一个连续的多核苷酸链组成，除了两端的短单链发夹环外，该多核苷酸链是完全碱基配对的。16 kb质粒的左右端粒在前19个核苷酸位置中有16个是相同的，彼此构成了一个反向末端重复。菌株B31的49kb质粒的左端粒与16kb质粒的端粒完全相同。不同大小的其他伯氏疏螺旋体菌株的质粒也含有与16kb质粒左端同源的序列。当将疏螺旋体端粒与其他线性双链DNA复制子的端粒序列进行比较时，发现序列与痘病毒，特别是与非洲猪瘟的虹膜病毒剂相似。后一种病毒和伯氏疏螺旋体具有相同的蜱虫媒介。这些发现表明，伯氏疏螺旋体的新型线性质粒起源于跨王国的水平遗传转移。
Spirochetes of the genus Borrelia have double-stranded linear plasmids with covalently closed ends. The physical nature of the terminal connections was determined for the 16-kb linear plasmid of the B31 strain of the Lyme disease agent Borrelia burgdorferi. Native telomeric fragments representing the left and right ends of this plasmid were isolatd and subjected to Maxam-Gilbert sequence analysis. At the plasmid ends the two DNA strands formed an uninterrupted, perfectly palindromic, AT-rich sequence. This Borrelia linear plasmid consisted of a continuous polynucleotide chain that is fully base paired except for short single-stranded hairpin loops at each end. The left and right telomeres of the 16-kb plasmid were identical for 16 of the first 19 nucleotide positions and constituted an inverted terminal repeat with respect to each other. The left telomere of the 49-kb plasmid of strain B31 was identical to the corresponding telomere of the 16-kb plasmid. Different-sized plasmids of other strains of B. burgdorferi also contained sequences homologous to the left end of the 16-kb plasmid. When the borrelia telomeres were compared with telomeric sequences of other linear double-stranded DNA replicons, sequence similarities were noted with poxviruses and particularly with the iridovirus agent of African swine fever. The latter virus and a Borrelia sp. share the same tick vector. These findings suggest that the novel linear plasmids of Borrelia originated through a horizontal genetic transfer across kingdoms.