Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany.
J Bacteriol. 2013 Sep;195(18):4146-53. doi: 10.1128/JB.00754-13. Epub 2013 Jul 12.
The emergence of Acinetobacter baumannii as an increasingly multidrug-resistant nosocomial pathogen largely relies on acquisition of resistance genes via horizontal gene transfer. Here, we demonstrate that many clinical isolates of A. baumannii take up DNA while they move along wet surfaces. We show that both motility and DNA uptake are abolished after inactivation of pilT, which putatively encodes the type 4 pilus (T4P) retraction ATPase, and comEC, which putatively encodes the DNA uptake channel, respectively. Inactivation of pilT correlates with an increase in the number and length of pili with an average diameter of 7.2 nm. In the Galleria mellonella infection model, the comEC mutant is significantly attenuated, whereas the pilT mutant is not, dissecting biologically distinct roles of T4P and the DNA uptake channel. Collectively, these findings promote our understanding of the mechanisms of DNA uptake and resistance development in A. baumannii, which may also apply to other important pathogens.
鲍曼不动杆菌作为一种日益具有多药耐药性的医院病原体的出现，主要依赖于通过水平基因转移获得耐药基因。在这里，我们证明，许多临床分离株的鲍曼不动杆菌在潮湿表面上移动时会摄取 DNA。我们表明，运动性和 DNA 摄取分别在 pilT 失活后被废除，推测 pilT 编码第四型菌毛（T4P）回缩 ATP 酶，而 comEC 则推测编码 DNA 摄取通道。pilT 的失活与菌毛数量和长度的增加相关，菌毛的平均直径为 7.2nm。在金龟子幼虫感染模型中，comEC 突变体明显减弱，而 pilT 突变体则没有，这揭示了 T4P 和 DNA 摄取通道的生物学上不同的作用。总的来说，这些发现促进了我们对鲍曼不动杆菌中 DNA 摄取和耐药性发展机制的理解，这可能也适用于其他重要的病原体。
