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Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues
Published on: November 22, 2014
Methionine acts as a "magnet" in photoaffinity crosslinking experiments
Angela Wittelsberger1, Beena E Thomas, Dale F Mierke
1Department of Physiology, Tufts University School of Medicine, 136 Harrison Ave, M&V 7, Boston, MA 02111, USA. Angela.Wittelsberger@tufts.edu
FEBS Letters
|March 7, 2006
Summary
Photoaffinity crosslinking reveals methionine
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Photoaffinity crosslinking is used to study ligand-receptor interactions in G protein-coupled receptors.
- Benzophenone photophores in ligands often react with receptor methionine residues.
Purpose of the Study:
- To investigate the role of methionine in defining crosslinking sites within the parathyroid hormone receptor.
- To explore the spatial range of crosslinking interactions mediated by methionine.
Main Methods:
- Site-directed mutagenesis to introduce single methionines into the parathyroid hormone receptor (residues 163-176).
- Photoaffinity crosslinking experiments using benzophenone-containing ligands.
- Analysis of crosslinking sites within the receptor.
Main Results:
- Crosslinking occurred with methionines introduced across an 11-amino acid region.
- Methionine residues acted as "magnet" sites, attracting crosslinking.
- The precise crosslinking contact point could be shifted by methionine placement.
Conclusions:
- Methionine residues significantly influence and broaden the observed crosslinking sites.
- This "Magnet Effect" allows for mapping receptor-ligand interfaces with greater spatial flexibility.
