Ellison Taylor J, Ellison Courtney K
Department of Microbiology, University of Georgia, Athens, GA 30602, United States.
Nucleic Acids Res. 2025 May 22;53(10). doi: 10.1093/nar/gkaf467.
Bacteria take up environmental DNA using dynamic appendages called type IV pili (T4P) to elicit horizontal gene transfer in a process called natural transformation. Natural transformation is widespread amongst bacteria yet the parameters that enhance or limit this process across species are poorly understood. We show that the most naturally transformable species known, Acinetobacter baylyi, owes this property to uniquely high levels of DNA binding by its orphan minor pilin, FimT. Expression of A. baylyi FimT in a closely related Acinetobacter pathogen substantially improves its capacity for natural transformation, showing that the acquisition of a single gene is sufficient to increase rates of horizontal gene transfer. We show that, compared with its homologs, A. baylyi FimT contains multiple regions of positively charged residues that additively promote DNA binding efficiency. These results demonstrate the importance of T4P-DNA binding in establishing natural transformation rates and provide a basis for improving or limiting this mechanism of horizontal gene transfer in different species.
细菌利用称为IV型菌毛（T4P）的动态附属物摄取环境DNA，在一个称为自然转化的过程中引发水平基因转移。自然转化在细菌中广泛存在，但不同物种中增强或限制这一过程的参数却知之甚少。我们发现，已知自然转化能力最强的物种——拜氏不动杆菌，其这种特性归因于其孤儿型次要菌毛蛋白FimT独特的高水平DNA结合能力。将拜氏不动杆菌的FimT基因在一种密切相关的不动杆菌病原体中表达，可显著提高其自然转化能力，这表明获得单个基因就足以提高水平基因转移的速率。我们还发现，与同源物相比，拜氏不动杆菌的FimT含有多个带正电荷的残基区域，这些区域可累加促进DNA结合效率。这些结果证明了T4P-DNA结合在确定自然转化率中的重要性，并为改进或限制不同物种中这种水平基因转移机制提供了依据。
