Phosphorylation Induces Conformational Rigidity at the C‑Terminal Domain of AMPA Receptors

• Published in: The journal of physical chemistry. B 2019-01, Vol.123 (1), p.130-137
• Main Authors: Chatterjee, Sudeshna, Ade, Carina, Nurik, Caitlin E, Carrejo, Nicole C, Dutta, Chayan, Jayaraman, Vasanthi, Landes, Christy F
• Format: Article
• Language: English
• Subjects: algorithms; amino acid sequences; energy transfer; ion channels; phosphorylation; receptors; spectroscopy
• ISSN: 1520-6106; 1520-5207; 1520-5207
• DOI: 10.1021/acs.jpcb.8b10749

The intracellular C-terminal domain (CTD) of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor undergoes phosphorylation at specific locations during long-term potentiation. This modification enhances conductance through the AMPA receptor ion channel and thus potentially plays a crucial role in modulating receptor trafficking and signaling. However, because the CTD structure is largely unresolved, it is difficult to establish if phosphorylation induces conformational changes that might play a role in enhancing channel conductance. Herein, we utilize single-molecule Förster resonance energy transfer (smFRET) spectroscopy to probe the conformational changes of a section of the AMPA receptor CTD, under the conditions of point-mutated phosphomimicry. Multiple analysis algorithms fail to identify stable conformational states within the smFRET distributions, consistent with a lack of well-defined secondary structure. Instead, our results show that phosphomimicry induces conformational rigidity to the CTD, and such rigidity is electrostatically tunable.