Ammor Mohammed Salim, Flórez Ana Belén, Alvarez-Martín Pablo, Margolles Abelardo, Mayo Baltasar
Departamento de Microbiología y Bioquímica, Instituto de Productos Lácteos de Asturias (CSIC), Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain.
J Antimicrob Chemother. 2008 Oct;62(4):688-93. doi: 10.1093/jac/dkn280. Epub 2008 Jul 8.
The tet(W) gene provides tetracycline resistance to a wide range of anaerobic intestinal and ruminal bacteria, but little is known about the molecular organization of the tet(W) gene. The aim of this study was to gain new insights into the molecular organization of the tet(W) gene in bifidobacteria strains from humans.
A segment of DNA encompassing the whole tet(W) gene and its immediate upstream and downstream sequences was analysed in 10 representative strains of four Bifidobacterium species, of which two have been shown to be tetracycline-susceptible. The non-conserved flanking regions of the tet(W) gene were further analysed in six strains.
All 10 strains share a core DNA domain of 2154 bp [starting 250 bp upstream of the tet(W) gene start codon and ending 13 bp before the stop codon] with 98% to 100% DNA identity. Except for Bifidobacterium animalis E43, all other strains further share 408 bp upstream and 70 bp downstream of the tet(W) gene. An insertion-like element of 736 bp was found to interrupt the tet(W) coding sequence in Bifidobacterium longum M21, which may be the reason for its tetracycline susceptibility. However, genetic events explaining the susceptible phenotype of B. longum LMG 13197(T) were not observed.
The tet(W) genes from all 10 strains shared 98% to 100% DNA and amino acid identity, though large variation was found in their flanking regions.
tet（W）基因赋予多种厌氧肠道和瘤胃细菌四环素抗性，但对tet（W）基因的分子结构了解甚少。本研究的目的是深入了解来自人类的双歧杆菌菌株中tet（W）基因的分子结构。
分析了四种双歧杆菌属的10株代表性菌株中包含整个tet（W）基因及其紧邻的上游和下游序列的一段DNA，其中两株已被证明对四环素敏感。对6株菌株中tet（W）基因的非保守侧翼区域进行了进一步分析。
所有10株菌株共享一个2154 bp的核心DNA结构域[从tet（W）基因起始密码子上游250 bp开始，到终止密码子前13 bp结束]，DNA同一性为98%至100%。除动物双歧杆菌E43外，所有其他菌株在tet（W）基因上游还共享408 bp，下游共享70 bp。在长双歧杆菌M21中发现一个736 bp的插入样元件中断了tet（W）编码序列，这可能是其对四环素敏感的原因。然而，未观察到解释长双歧杆菌LMG 13197（T）敏感表型的遗传事件。
所有10株菌株的tet（W）基因DNA和氨基酸同一性均为98%至100%，但其侧翼区域存在较大差异。
