Nucleoid restructuring in stationary-state bacteria.
The textbook view of the bacterial cytoplasm as an unstructured environment has been overturned recently by studies that highlighted the extent to which non-random organization and coherent motion of intracellular components are central for bacterial life-sustaining activities. Because such a dynamic order critically depends on continuous consumption of energy, it cannot be perpetuated in starved, and hence energy-depleted, stationary-state bacteria. Here, we show that, at the onset of the stationary state, bacterial chromatin undergoes a massive reorganization into ordered toroidal structures through a process that is dictated by the intrinsic properties of DNA and by the ubiquitous starvation-induced DNA-binding protein Dps. As starvation proceeds, the toroidal morphology acts as a structural template that promotes the formation of DNA-Dps crystalline assemblies through epitaxial growth. Within the resulting condensed assemblies, DNA is effectively protected by means of structural sequestration. We thus conclude that the transition from bacterial active growth to stationary phase entails a co-ordinated process, in which the energy-dependent dynamic order of the chromatin is sequentially substituted with an equilibrium crystalline order.
Frenkiel-Krispin
Daphna
D
Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
Ben-Avraham
Irit
I
Englander
Joseph
J
Shimoni
Eyal
E
Wolf
Sharon G
SG
Minsky
Abraham
A
D004269:DNA, Bacterial / Q000235:genetics* / Q000648:ultrastructure*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure*; D007091:Image Processing, Computer-Assisted; D014054:Tomography / Q000379:methods
D004269:DNA, Bacterial; D004268:DNA-Binding Proteins