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bioRxiv · 10.1101/097436

Environment driven conformational changes modulate H-NS DNA bridging activity

van der Valk, R. A.·Vreede, J.·Moolenaar, G. F.·Hofmann, A.·Goosen, N.·Dame, R. T.
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Abstract

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.

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van der Valk, R. A., Vreede, J., Moolenaar, G. F., Hofmann, A., Goosen, N., Dame, R. T.. 2016-12-30. Environment driven conformational changes modulate H-NS DNA bridging activity. https://doi.org/10.1101/097436

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