Recent Articles

Maier B, Chen I, Dubnau D, Sheetz MP. (2004).
DNA transport into Bacillus subtilis requires proton motive force to generate large molecular forces.
Nat Struct Mol Biol. 2004 Jul;11(7):643-9. Epub 2004 Jun 06.
PMID: 15184891

Bacteria can acquire genetic diversity, including antibiotic resistance and virulence traits, by horizontal gene transfer. In particular, many bacteria are naturally competent for uptake of naked DNA from the environment in a process called transformation. Here, we used optical tweezers to demonstrate that the DNA transport machinery in Bacillus subtilis is a force-generating motor. Single DNA molecules were processively transported in a linear fashion without observable pausing events. Uncouplers inhibited DNA uptake immediately, suggesting that the transmembrane proton motive force is needed for DNA translocation. We found an uptake rate of 80 +/- 10 bp s(-1) that was force-independent at external forces <40 pN, indicating that a powerful molecular machine supports DNA transport.