Extremophilic prokaryotes live under harsh environmental conditions which require far-reaching cellular adaptations. The acquisition of novel genetic information via natural transformation plays an important role in bacterial adaptation. This mode of DNA transfer permits the transfer of genetic information between microorganisms of distant evolutionary lineages and even between members of different domains. This phenomenon, known as horizontal gene transfer (HGT), significantly contributes to genome plasticity over evolutionary history and is a driving force for the spread of fitness-enhancing functions including virulence genes and antibiotic resistances. In particular, HGT has played an important role for adaptation of bacteria to extreme environments. Here, we present a survey of the natural transformation systems in bacteria that live under extreme conditions: the thermophile Thermus thermophilus and two desiccation-resistant members of the genus Acinetobacter such as Acinetobacter baylyi and Acinetobacter baumannii. The latter is an opportunistic pathogen and has become a world-wide threat in health-care institutions. We highlight conserved and unique features of the DNA transporter in Thermus and Acinetobacter and present tentative models of both systems. The structure and function of both DNA transporter are described and the mechanism of DNA uptake is discussed.

极端嗜热原核生物生活在恶劣的环境条件下，需要广泛的细胞适应。通过自然转化获得新的遗传信息在细菌适应中起着重要作用。这种 DNA 转移模式允许在远距离进化谱系的微生物之间，甚至在不同域的成员之间转移遗传信息。这种被称为水平基因转移 (HGT) 的现象显着促进了进化历史中的基因组可塑性，并且是促进适应性增强功能（包括毒力基因和抗生素抗性）传播的驱动力。特别是，HGT在细菌适应极端环境方面发挥了重要作用。这里，Thermus嗜热菌和属的2耐干燥构件不动杆菌如不动杆菌属baylyi和鲍曼不动杆菌。后者是一种机会性病原体，已成为全球卫生保健机构的威胁。我们强调了栖热菌和不动杆菌中DNA 转运蛋白的保守和独特特征，并提出了这两个系统的暂定模型。描述了两种 DNA 转运蛋白的结构和功能，并讨论了 DNA 摄取的机制。