Low-force DNA condensation and discontinuous high-force decondensation reveal a loop-stabilizing function of the protein Fis.
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.
Skoko
Dunja
D
Department of Physics, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7059, USA.
Yan
Jie
J
Johnson
Reid C
RC
Marko
John F
JF
D004269:DNA, Bacterial / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D035021:Factor For Inversion Stimulation Protein; D033081:Shear Strength; D014157:Transcription Factors / Q000737:chemistry*
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; C501034:Fis protein, E coli; D014157:Transcription Factors