Periplasmic Binding Protein Dimer Has a Second Allosteric Event Tied to Ligand Binding

By Le Li, Sudipa Ghimire-Rijal, Sarah L. Lucas, Christopher B. Stanley, Edward Wright, Pratul K. Agarwal, Dean A. Myles, Matthew J. Cuneo

May 22, 2018

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Title

Periplasmic Binding Protein Dimer Has a Second Allosteric Event Tied to Ligand Binding

Author

Le Li, Sudipa Ghimire-Rijal, Sarah L. Lucas, Christopher B. Stanley, Edward Wright, Pratul K. Agarwal, Dean A. Myles, Matthew J. Cuneo

Year

2017

Journal

Biochemistry

Abstract

The ligand-induced conformational changes of periplasmic binding proteins (PBP) play a key role in the acquisition of metabolites in ATP binding cassette (ABC) transport systems. This conformational change allows for differential recognition of the ligand occupancy of the PBP by the ABC transporter. This minimizes futile ATP hydrolysis in the transporter, a phenomenon in which ATP hydrolysis is not coupled to metabolite transport. In many systems, the PBP conformational change is insufficient at eliminating futile ATP hydrolysis. Here we identify an additional state of the PBP that is also allosterically regulated by the ligand. Ligand binding to the homodimeric apo PBP leads to a tightening of the interface α-helices so that the hydrogen bonding pattern shifts to that of a 310 helix, in-turn altering the contacts and the dynamics of the protein interface so that the monomer exists in the presence of ligand.

Full Article

http://pubs.acs.org/doi/abs/10.1021/acs.biochem.7b00657

Instrument

J-???

Keywords

Circular dichroism, Secondary structure, Ligand binding, Thermal stability, Thermodynamics, Biochemistry