Open AccessEngineering the hCRBPII Domain-Swapped Dimer into a New Class of Protein Switches
Author(s) -
A. Ghanbarpour,
Cody Pinger,
Rahele Esmatpour Salmani,
Z. Assar,
Elizabeth Moreira dos Santos,
Meisam Nosrati,
Kathryn Pawlowski,
Dana M. Spence,
Chrysoula Vasileiou,
Xiangshu Jin,
Babak Borhan,
James H. Geiger
Publication year - 2019
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/jacs.9b04664
Subject(s) - allosteric regulation , chemistry , dimer , conformational change , allosteric enzyme , steric effects , protein structure , resolution (logic) , biophysics , stereochemistry , crystallography , biochemistry , receptor , organic chemistry , artificial intelligence , computer science , biology
Protein conformational switches or allosteric proteins play a key role in the regulation of many essential biological pathways. Nonetheless, the implementation of protein conformational switches in protein design applications has proven challenging, with only a few known examples that are not derivatives of naturally occurring allosteric systems. We have discovered that the domain-swapped (DS) dimer of hCRBPII undergoes a large and robust conformational change upon retinal binding, making it a potentially powerful template for the design of protein conformational switches. Atomic resolution structures of the apo- and holo-forms illuminate a simple, mechanical movement involving sterically driven torsion angle flipping of two residues that drive the motion. We further demonstrate that the conformational "readout" can be altered by addition of cross-domain disulfide bonds, also visualized at atomic resolution. Finally, as a proof of principle, we have created an allosteric metal binding site in the DS dimer, where ligand binding results in a reversible 5-fold loss of metal binding affinity. The high resolution structure of the metal-bound variant illustrates a well-formed metal binding site at the interface of the two domains of the DS dimer and confirms the design strategy for allosteric regulation.