The 44‐kb Linear Plasmid Molecule in the Relapsing Fever Agent Borrelia duttonii Strain Ly Serve as a Preservation of vmp Genes
The 44‐kb Linear Plasmid Molecule in the Relapsing Fever Agent Borrelia duttonii Strain Ly Serve as a Preservation of vmp Genes
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回归热病原伯氏疏螺旋体菌株中的 44 kb 线性质粒分子可作为 vmp 基因的保存
DOI：
10.1111/j.1348-0421.2002.tb02681.x
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发表时间：
2002
影响因子：
2.6
通讯作者：
M. Fukunaga
中科院分区：
文献类型：
--
作者：
N. Tabuchi;H. Mitani;S. Seino;M. Fukunaga
杜氏疏螺旋体Ly株是引起复发性发热的病原，它含有一个线性的1兆碱基染色体和12个线性的质粒分子。在此，我们发现Ly株44kb的线性质粒序列含有与复发性疏螺旋体抗原性变异相关的主要蛋白(VMp)基因。测得的序列除分子两端外，其余均为44,010个核苷酸。在序列中发现的39个开放阅读框(ORF)中，有21个ORF(命名为VMPA至U)与赫氏疏螺旋体的vmp基因有一定的相似性。然而，大多数VMP同源物显然是无功能的，因为它们在序列中发生了框架移位和/或在其基因上游没有启动子和核糖体结合信号。用每个vmp基因的特异性引物进行RT-PCR实验表明，vmpE基因在44kb的质粒分子上表达。这一结果表明，该质粒分子可能在哺乳动物宿主中保护VMP基因的血清型转换中起作用。
Borrelia duttonii strain Ly, a causative agent of relapsing fever, contains a linear one megabase chromosome and 12 linear plasmid molecules. Here we report that the sequence of the 44‐kb linear plasmid of strain Ly is found to contain variable major protein (vmp) genes for antigenic variation of relapsing fever borreliae. The determined sequence is of 44,010 bp except for both ends of the molecule. Of 39 open reading frames (ORFs) found in the sequence, 21 ORFs (named vmpA to U) showed moderate similarities with vmp genes for Borrelia hermsii. However, most of the vmp homologues are apparently nonfunctional because of their frameshifts within the sequence and/or absence of promoter and ribosome‐binding signals upstream of their genes. RT‐PCR experiments using the specific primer for each vmp gene revealed that vmpE, one of the vmp genes, was expressed at the location of the 44‐kb plasmid molecule. The result suggests that the plasmid molecule may play a role in the preservation of the serotype switching of vmp genes in a mammalian host.
DOI：
10.1073/pnas.97.25.13865
发表时间：
2000-12-05
影响因子：
11.1
作者：
Purser, JE;Norris, SJ
通讯作者：
Norris, SJ