Natural transformation is a broadly conserved mechanism of horizontal gene transfer in
bacterial species that can shape evolution and foster the spread of antibiotic resistance
determinants, promote antigenic variation and lead to the acquisition of novel virulence
factors. Surface appendages called competence pili promote DNA uptake during the first
step of natural transformation; however, their mechanism of action has remained unclear
owing to an absence of methods to visualize these structures in live cells. Here, using the …