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Effects of Cardiolipin on the Conformational Dynamics of Membrane-Anchored Bcl-xL

Vivek Tyagi1, Victor Vasquez-Montes2, J Alfredo Freites3

  • 1Department of Materials Science and Engineering, University of California, Irvine, CA 92697, USA.

International Journal of Molecular Sciences
|September 10, 2021
PubMed

Insights

The anti-apoptotic protein Bcl-xL

Area of Science:

  • Biochemistry and Molecular Biology
  • Cell Biology
  • Structural Biology

Background:

  • The anti-apoptotic protein Bcl-xL inhibits programmed cell death by blocking mitochondrial outer membrane permeabilization.
  • Bcl-xL exists in membrane-anchored and membrane-inserted conformations.
  • Understanding Bcl-xL's conformational dynamics is crucial for its role in apoptosis regulation.

Purpose of the Study:

  • To investigate how cardiolipin and protein protonation state affect the conformational dynamics of membrane-anchored Bcl-xL.
  • To determine the impact of these factors on the exposure of Bcl-xL's BH3-binding groove.

Main Methods:

  • Molecular dynamics simulations were employed to model membrane-anchored Bcl-xL.
  • The simulations incorporated mitochondrial-specific lipid cardiolipin and varied protein protonation states.

Main Results:

  • Both protein protonation state and cardiolipin content significantly modulate Bcl-xL's conformation.
  • These factors influence the orientation of Bcl-xL's soluble head region (helices α1-α7).
  • The exposure of the BH3-binding groove is altered by these modulations.

Conclusions:

  • Cardiolipin and protein protonation are key regulators of membrane-anchored Bcl-xL's conformation.
  • These regulatory mechanisms control the accessibility of the BH3-binding groove.
  • This conformational control is essential for Bcl-xL's interaction with pro-apoptotic proteins and apoptosis regulation.
Keywords:
BCL-2 proteinsBH3-binding siteBcl-xLapoptotic regulationcardiolipinmolecular dynamics simulationsprotein–membrane interactions

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