This paper describes the de novo design of pH-responsive protein filaments using subunits with six or nine buried histidine residues. These subunits assemble into micrometre-scale fibres at neutral pH and exhibit a sharp, reversible transition between assembled and disassembled states over a narrow pH range (0.3 pH units). The transition midpoint is tunable by altering the histidine-containing hydrogen bond networks. Cryogenic electron microscopy confirmed the designed structure. This work demonstrates a computational design route for creating responsive nanomaterials.

Hao Shen, Eric M. Lynch, Susrut Akkineni, Joseph L. Watson, Justin Decarreau, Neville P. Bethel, Issa Benna, William Sheffler, Daniel Farrell, Frank DiMaio, Emmanuel Derivery, James J. De Yoreo, Justin Kollman, David Baker