Interchangeable regulatory domains: exploring modular allostery en route to chorismate

Fan Y1,2,5, Cross PJ2,5, Jameson GB3 and Parker EJ1,4

  1. Ferrier Research Institute, Victoria University of Welington, 6140 Wellington, New Zealand.
  2. Department of Chemistry, University of Canterbury, 8140 Christchurch, New Zealand.
  3. Maurice Wilkins Centre, Institute of Fundamental Sciences, Massey University, 4442 Palmerston North, New Zealand.
  4. Maurice Wilkins Centre, Biomolecular Interaction Centre, University of Canterbury, 8140 Christchurch, New Zealand.
  5. Biomolecular Interaction Centre, University of Canterbury, 8140 Christchurch, New Zealand.

Engineering desired function into proteins via manipulation of the genes, mimicking natural evolutionary processes, represents a promising approach to synthesizing useful molecular tools. Most proteins comprise two or more domains from a limited suite of protein families. These domains are often rearranged in various combinations through gene fusion events to evolve new protein functions, including the acquisition of protein allostery through the incorporation of regulatory domains. The enzyme 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAH7PS) is the first enzyme of aromatic amino acid biosynthesis and displays a diverse range of allosteric mechanisms. DAH7PSs adopt a common architecture with a shared (β/α)8 catalytic domain which can be attached to an ACT-like or a chorismate mutase regulatory domain that operates via distinct mechanisms. These respective domains confer allosteric regulation by controlling DAH7PS function in response to ligand tyrosine or prephenate. Starting with contemporary DAH7PS proteins, two protein chimeras were created, with interchanged regulatory domains. Both engineered proteins were catalytically active and delivered new functional allostery with switched ligand specificity and allosteric mechanisms delivered by their nonhomologous regulatory domains. This interchangeability of protein domains represents an efficient method not only to engineer allostery in multidomain proteins but to create a new bifunctional enzyme.1 1. Fan, Y., Cross, P.J., Jameson, G.B. and Parker, E.J., 2018. Exploring modular allostery via interchangeable regulatory domains. Proceedings of the National Academy of Sciences, 115(12), pp.3006-3011.