DNA binding is rate-limiting for natural transformation.

Natural transformation is a multi-step, broadly conserved mechanism for horizontal gene transfer in which bacteria take up exogenous DNA from the environment and integrate it into their genome by homologous recombination. A complete picture of the factors that limit this behavior remain unclear due to variability between bacterial systems. In this manuscript, we provide clear and direct evidence that DNA binding by type IV pili prior to DNA uptake is a rate-limiting step of natural transformation. We show that increasing DNA binding in antibiotic resistant Acinetobacter pathogens can boost their transformation rates by 100-fold. In addition to expanding our understanding of the factors that limit transformation in the environment, these results will also contribute to a deeper understanding of the spread of antibiotic resistance genes in relevant human pathogens.