An alternative flexible conformation of the E. coli HUβ₂ protein: structural, dynamics, and functional aspects.

The histone-like HU protein is the major nucleoid-associated protein involved in the dynamics and structure of the bacterial chromosome. Under physiological conditions, the three possible dimeric forms of the E. coli HU protein (EcHUα₂, EcHUβ₂, and EcHUαβ) are in thermal equilibrium between two dimeric conformations (N₂ ↔ I₂) varying in their secondary structure content. High-temperature molecular dynamics simulations combined with NMR experiments provide information about structural and dynamics features at the atomic level for the N₂ to I₂ thermal transition of the EcHUβ₂ homodimer. On the basis of these data, a realistic 3D model is proposed for the major I₂ conformation of EcHUβ₂. This model is in agreement with previous experimental data.