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Non-Canonical Amino Acids As Biochemical Probes of Ligand-Gated Ion Channel Structure and Function


Rienzo, Matthew (2017) Non-Canonical Amino Acids As Biochemical Probes of Ligand-Gated Ion Channel Structure and Function. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9G44N8W.


This dissertation describes several different chemical-scale studies of proteins involved in cellular signaling. The primary focus of this work is on ligand-gated ion channels, an important family of membrane receptors. In each study, the incorporation of structurally diverse non-canonical amino acids have been used to attain a high level of precision in probing the mechanisms of molecular processes. The first chapter provides an introduction to the nonsense suppression methodology used to genetically encode these probes, and surveys the classes of proteins studied herein.

The second and third chapters are concerned with the mechanism of activation of a prokaryotic receptor, Gloeobacter violaceus ligand-gated ion channel. In these experiments, novel histidine derivatives were designed, synthesized, and incorporated to test the functional importance of acid-base titration at several positions in the receptor. Then, a battery of proline analogs were used to identify necessary structural features of several critical proline residues, providing clues to conformational changes that occur during receptor activation.

The fourth chapter discusses studies of a different class of receptors, the Acid-Sensing Ion Channels. Several fluorinated aspartic acid and glutamic acid derivatives were targeted to modulate the acidity of putative proton binding sites. Attempts at preparation of these compounds for incorporation into proteins are detailed. Additional sections describe, efforts to elucidate factors in the binding selectivity of the tarantula venom psalmotoxin and selectivity of cation permeability.

In the final chapter, early efforts at developing crosslinking assays for protein-protein interactions in mammalian cells are outlined. These assays involve the introduction of orthogonal tRNA/synthetase pairs for genetically encoding photoreactive phenylalanine analogs. The most successful studies involve the ligand-dependent dimerization of the soluble nuclear receptor, estrogen receptor α. However, the ultimate goal of this work is to to probe protein-protein interactions among membrane receptors and other proteins. Progress toward extension of the photocrosslinking assay into membrane receptors is described.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:non-canonical amino acid; ion channel; crosslinking; GLIC; acid-sensing ion channel; histidine; proline; nonsense suppression
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Dougherty, Dennis A.
Thesis Committee:
  • Shan, Shu-ou (chair)
  • Tirrell, David A.
  • Grubbs, Robert H.
  • Dougherty, Dennis A.
Defense Date:17 August 2016
Non-Caltech Author Email:mrienzo42 (AT)
Record Number:CaltechTHESIS:09022016-105040371
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Ch. 2 adapted for Ch. 3
Rienzo, Matthew0000-0002-9389-1310
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9910
Deposited By: Matthew Rienzo
Deposited On:19 Sep 2016 21:44
Last Modified:07 Nov 2022 23:43

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