Biology subjects

Dame, R. T.

Publications and source records attributed to Dame, R. T..

2 recordsLinked to original sources

bioRxiv2018

The bacterial chromatin protein HupA can remodel DNA and associates with the nucleoid in Clostridium difficile

The maintenance and organization of the chromosome plays an important role in the development and survival of bacteria. Bacterial chromatin proteins are architectural proteins that bind DNA, modulate its conformation and by doing so affect a variety of cellular processes. No bacterial chromatin proteins of C. difficile have been characterized to date.\n\nHere, we investigate aspects of the C. difficile HupA protein, a homologue of the histone-like HU proteins of Escherichia coli. HupA is a 10 kDa protein that is present as a homodimer in vitro and self-interacts in vivo. HupA co-localizes with the nucleoid of C. difficile. It binds to the DNA without a preference for the DNA G+C content. Upon DNA binding, HupA induces a conformational change in the substrate DNA in vitro and leads to compaction of the chromosome in vivo.\n\nThe present study is the first to characterize a bacterial chromatin protein in C. difficile and opens the way to study the role of chromosomal organization in DNA metabolism and on other cellular processes in this organism.

microbiology↗

bioRxiv2016

Environment driven conformational changes modulate H-NS DNA bridging activity

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.

biochemistry↗