Plastic cells and populations:: DNA substrate characteristics in Helicobacter pylori transformation define a flexible but conservative system for genomic variation
Plastic cells and populations:: DNA substrate characteristics in Helicobacter pylori transformation define a flexible but conservative system for genomic variation
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DOI：
10.1096/fj.07-8501com
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发表时间：
2007-11-01
期刊：
影响因子：
4.8
通讯作者：
Blaser, Martin J.
中科院分区：
文献类型：
--
作者：
Levine, Steven M.;Lin, Edward A.;Blaser, Martin J.
幽门螺杆菌是一种寄生于胃粘膜的细菌，它具有天然的外源DNA转化能力，并表现出一种泛菌群结构。为了了解其水平基因转移的机制，我们试图确定从暴露于底物DNA直到DNA摄取和表达可选表型所需的时间间隔，以及转化片段长度、浓度、同源性、对称性和链型与转化频率的关系。我们提供的证据表明，在H。幽门螺杆菌野生型菌株之间的效率不同，但可饱和，并随底物DNA长度、对称性、链型和物种来源而变化。我们证明了H.幽门螺杆菌细胞可以在与DNA接触的一分钟内被小至50bp的DNA片段转化，并且在可选择的单核苷酸突变的一侧上的少至5bp的DNA片段是转化片段重组的足够底物，并且双链DNA是优选的（1000倍于单链）底物。双链DNA作为转化底物，与菌株特异性限制性内切酶结合的高效率表明了有利于最近亲属的短片段重组模型，与观察到的H. pylori群体生物学
Helicobacter pylori, bacteria that colonize the human gastric mucosa, are naturally competent for transformation by exogenous DNA, and show a panmictic population structure. To understand the mechanisms involved in its horizontal gene transfer, we sought to define the interval required from exposure to substrate DNA until DNA uptake and expression of a selectable phenotype, as well as the relationship of transforming fragment length, concentration, homology, symmetry, and strandedness, to the transformation frequency. We provide evidence that natural transformation in H. pylori differs in efficiency among wild-type strains but is saturable and varies with substrate DNA length, symmetry, strandedness, and species origin. We show that H. pylori cells can be transformed within one minute of contact with DNA, by DNA fragments as small as 50 bp, and as few as 5 bp on one flank of a selectable single nucleotide mutation is sufficient substrate for recombination of a transforming fragment, and that double-stranded DNA is the preferred (1000-fold > single-stranded) substrate. The high efficiency of double-stranded DNA as transformation substrate, in conjunction with strain-specific restriction endonucleases suggests a model of short-fragment recombination favoring closest relatives, consistent with the observed H. pylori population biology.