Portal de Periódicos da CAPES

The antiparallel loops in gal DNA

2008; Oxford University Press; Volume: 36; Issue: 12 Linguagem: Inglês

10.1093/nar/gkn389

1362-4962

Giuseppe Lia, Szabolcs Semsey, Dale E. A. Lewis, S. Adhya, David Bensimon, David Dunlap, Laura Finzi,

Bacterial Genetics and Biotechnology

Interactions between proteins bound to distant sites along a DNA molecule require bending and twisting deformations in the intervening DNA. In certain systems, the sterically allowed protein–DNA and protein–protein interactions are hypothesized to produce loops with distinct geometries that may also be thermodynamically and biologically distinct. For example, theoretical models of Gal repressor/HU-mediated DNA-looping suggest that the antiparallel DNA loops, A1 and A2, are thermodynamically quite different. They are also biologically different, since in experiments using DNA molecules engineered to form only one of the two loops, the A2 loop failed to repress in vitro transcription. Surprisingly, single molecule measurements show that both loop trajectories form and that they appear to be quite similar energetically and kinetically.