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Illuminating Disorder Induced by Glu in a Stable Arg-Anchored Transmembrane Helix
Jake R Price1, Fahmida Afrose1, Denise V Greathouse1
1Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States.
ACS Omega
|August 16, 2021
Summary
Introducing a single glutamic acid (Glu) residue into a transmembrane helix dramatically induces protein disorder. This finding reveals how single residues can control protein behavior in lipid membranes.
Area of Science:
- Biochemistry
- Structural Biology
- Membrane Biophysics
Background:
- Membrane proteins are crucial for biological functions but challenging to study.
- The influence of specific chemical group interactions on membrane protein behavior is not fully understood.
- Disordered proteins are increasingly recognized for their roles in biological regulation.
Purpose of the Study:
- To investigate the impact of introducing a single glutamic acid (Glu) residue on the stability and dynamics of a transmembrane helix.
- To explore how this modification affects protein disorder and behavior within a lipid bilayer environment.
- To understand the fundamental mechanisms by which single amino acid substitutions can induce complex protein properties.
Main Methods:
- Utilized a 23-residue transmembrane helix model system.
- Incorporated a single glutamic acid (Glu) residue adjacent to a single arginine (Arg) residue.
- Employed deuterium (²H) NMR spectroscopy to monitor helix properties.
- Investigated the effects of varying pH and lipid bilayer composition (e.g., DOPC).
Main Results:
- A single Glu residue, positioned near an Arg residue, induced a remarkable transition from a stable helical state to multiple disordered states.
- The number of disordered states (three or more) was dependent on the radial separation between Glu and Arg.
- The observed disordered multistate behavior was sensitive to changes in pH and lipid bilayer thickness.
- The parent helix, anchored by Arg, exhibited well-defined tilt and precession, which was disrupted by Glu introduction.
Conclusions:
- A single glutamic acid residue can fundamentally induce multi-state disorder in a transmembrane helix within a lipid membrane.
- This finding highlights the significant impact of localized amino acid changes on protein dynamics and function.
- The results suggest a novel mechanism for controlling protein behavior and biological function through specific residue interactions in membrane environments.
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