Structural basis and mechanism of the unfolding-induced activation of HdeA, a bacterial acid response chaperone.

The role of protein structural disorder in biological functions has gained increasing attention in the past decade. The bacterial acid-resistant chaperone HdeA belongs to a group of "conditionally disordered" proteins, because it is inactive in its well-structured state and becomes activated via an order-to-disorder transition under acid stress. However, the mechanism for unfolding-induced activation remains unclear because of a lack of experimental information on the unfolded state conformation and the chaperone-client interactions.

Characterizations of the Interactions between Escherichia coli Periplasmic Chaperone HdeA and Its Native Substrates during Acid Stress.

The bacterial acid-resistant chaperone HdeA is a "conditionally disordered" protein that functions at low pH when it undergoes a transition from a well-folded dimer to an unfolded monomer. The dimer dissociation and unfolding processes result in exposure of hydrophobic surfaces that allows binding to a broad range of client proteins. To fully elucidate the chaperone mechanism of HdeA, it is crucial to understand how the activated HdeA interacts with its native substrates during acid stress.

TACN-based oligomers with aromatic backbones for efficient nucleic acid delivery.

Cationic oligomers with a rigid aromatic backbone were first applied as non-viral gene delivery vectors. These materials showed better DNA condensation ability than their flexible analogues. In vitro transfection experiments revealed that the materials with more rigid backbone exhibited considerably higher TE and lower cytotoxicity than 25 kDa PEI.