RT Journal Article
SR Electronic
T1 Environment driven conformational changes modulate H-NS DNA bridging activity
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 097436
DO 10.1101/097436
A1 Ramon A. van der Valk
A1 Jocelyne Vreede
A1 Geri F. Moolenaar
A1 Andreas Hofmann
A1 Nora Goosen
A1 Remus T. Dame
YR 2016
UL http://biorxiv.org/content/early/2016/12/30/097436.abstract
AB Bacteria frequently need to adapt to altered environmental conditions. Adaptation requires changes in gene expression, often mediated by global regulators of transcription. The nucleoid-associated protein H-NS is a key global regulator in Gram-negative bacteria, and is believed to be a crucial player in bacterial chromatin organization via its DNA bridging activity. H-NS activity in vivo is modulated by physico-chemical factors (osmolarity, pH, temperature) and interaction partners. Mechanistically it is unclear how functional modulation of H-NS by such factors is achieved. Here, we show that a diverse spectrum of H-NS modulators alter the ability of H-NS to bridge DNA. Changes in monovalent and divalent ion concentrations drive an abrupt switch between a bridging and non-bridging DNA binding mode. Similarly, synergistic and antagonistic co-regulators modulate the DNA bridging efficiency. Structural studies suggest a conserved mechanism: H-NS switches between a “closed” and an “open”, bridging competent, conformation driven by environmental cues and interaction partners.