The molecular basis of FimT-mediated DNA uptake during bacterial natural transformation

• Published in: Nature communications 2022-03, Vol.13 (1), p.1065-1065, Article 1065
• Main Authors: Braus, Sebastian A. G., Short, Francesca L., Holz, Stefanie, Stedman, Matthew J. M., Gossert, Alvar D., Hospenthal, Manuela K.
• Format: Article
• Language: English
• Subjects: 101/6; 631/326/41/1969/1852; 631/326/41/2536; 631/45/612/1229; 631/535/878/1263; 82/83; Bacterial Proteins - metabolism; DNA - metabolism; DNA, Bacterial - metabolism; Fimbriae Proteins - metabolism; Fimbriae, Bacterial - metabolism; Humanities and Social Sciences; Legionella pneumophila - genetics; Legionella pneumophila - metabolism; multidisciplinary; Science; Science (multidisciplinary); Transformation, Bacterial
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-28690-1

Naturally competent bacteria encode sophisticated protein machinery for the uptake and translocation of exogenous DNA into the cell. If this DNA is integrated into the bacterial genome, the bacterium is said to be naturally transformed. Most competent bacterial species utilise type IV pili for the initial DNA uptake step. These proteinaceous cell-surface structures are composed of thousands of pilus subunits (pilins), designated as major or minor according to their relative abundance in the pilus. Here, we show that the minor pilin FimT plays an important role in the natural transformation of Legionella pneumophila . We use NMR spectroscopy, in vitro DNA binding assays and in vivo transformation assays to understand the molecular basis of FimT’s role in this process. FimT binds to DNA via an electropositive patch, rich in arginines, several of which are well-conserved and located in a conformationally flexible C-terminal tail. FimT orthologues from other Gammaproteobacteria share the ability to bind to DNA. Our results suggest that FimT plays an important role in DNA uptake in a wide range of competent species. Many bacteria can take up exogenous DNA, in a process that often requires surface appendages composed of thousands of protein subunits called pilins. Here, Braus et al. show that a minor pilin binds directly to DNA and is important for DNA uptake in the pathogen Legionella pneumophila .