skoko low-force.pdf (228.22 kB)
Low-force DNA condensation and discontinuous high-force decondensation reveal a loop-stabilizing function of the protein Fis
journal contributionposted on 2009-08-08, 00:00 authored by Dunja Skoko, Jie Yan, Reid C. Johnson, John F. Marko
We report single-DNA-stretching experiments showing that the protein Fis, an abundant bacterial chromosome protein of E. coli, mediates a dramatic DNA condensation to zero length. This condensation occurs abruptly when DNA tension is reduced below a protein-concentration-dependent threshold f(*)< 1 pN. Following condensation, reopening under larger forces proceeds via a series of discrete jumps, indicating that Fis is able to stabilize DNA crossings. Our experiments suggest that Fis may play a role in vivo stabilizing the "loop-domain" structure of the bacterial chromosome.