A divalent switch drives H-NS/DNA-binding conformations between stiffening and bridging modes.
Heat-stable nucleoid structuring protein (H-NS) is an abundant prokaryotic protein that plays important roles in organizing chromosomal DNA and gene silencing. Two controversial binding modes were identified. H-NS binding stimulating DNA bridging has become the accepted mechanism, whereas H-NS binding causing DNA stiffening has been largely ignored. Here, we report that both modes exist, and that changes in divalent cations drive a switch between them. The stiffening form is present under physiological conditions, and directly responds to pH and temperature in vitro. Our findings have broad implications and require a reinterpretation of the mechanism by which H-NS regulates genes.
Department of Physics, National University of Singapore, Singapore 117542.
Yingjie
Y
Liu
Hu
H
Chen
Linda J
LJ
Kenney
Jie
J
Yan
D001426:Bacterial Proteins / Q000378:metabolism*; D002413:Cations, Divalent; D004269:DNA, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D006863:Hydrogen-Ion Concentration; D015636:Magnesium Chloride / Q000494:pharmacology; D009690:Nucleic Acid Conformation; D011108:Polymers / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D012475:Salmonella / Q000235:genetics* / Q000378:metabolism*; D013696:Temperature
D001426:Bacterial Proteins; D002413:Cations, Divalent; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; D011108:Polymers; D015636:Magnesium Chloride