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The Conformational Stability of Pro-apoptotic BAX is Dictated by Discrete Residues of the Protein Core

ABSTRACT: BAX is a pro-apoptotic member of the BCL-2 family, which regulates the balance between cellular life and death. During homeostasis, BAX predominantly resides in the cytosol as a latent monomer but, in response to stress, transforms into an oligomeric protein that permeabilizes the mitochondria, leading to cell death. Because renegade BAX activation poses a grave risk to the cell, the architecture of BAX must ensure monomeric stability yet simultaneously enable conformational change upon stress signaling. The specific structural features that afford both stability and dynamic flexibility remain ill-defined and represent a critical control point of BAX regulation. Here, we identified a nexus of interactions involving four discrete residues of the BAX core α5 helix that are individually essential to maintaining the structure and latency of monomeric BAX and are collectively required for dimeric assembly. We compared the HDX MS profile of full-length recombinant wild-type BAX in solution with that of the BAX L113A, F114A, Y115A, and F116A single point mutants. In each case, we observed striking, regiospecific consequences of replacing the bulky hydrophobic residue with alanine. We also compared HDX in a construct of α2-α5 for the wt protein as well as mutants. The dual yet distinct roles of these residues reveals the intricacy of BAX conformational regulation and opportunities for therapeutic modulation.

INSTRUMENT(S): Synapt MS

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: John R. Engen

LAB HEAD: John R. Engen

PROVIDER: PXD024479 | Pride | 2021-08-26

REPOSITORIES: Pride

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The conformational stability of pro-apoptotic BAX is dictated by discrete residues of the protein core.

Bloch Noah B NB Wales Thomas E TE Prew Michelle S MS Levy Hannah R HR Engen John R JR Walensky Loren D LD

Nature communications 20210813 1

BAX is a pro-apoptotic member of the BCL-2 family, which regulates the balance between cellular life and death. During homeostasis, BAX predominantly resides in the cytosol as a latent monomer but, in response to stress, transforms into an oligomeric protein that permeabilizes the mitochondria, leading to apoptosis. Because renegade BAX activation poses a grave risk to the cell, the architecture of BAX must ensure monomeric stability yet enable conformational change upon stress signaling. The sp ...[more]

PMID: 34389733

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	F114ABAX_10min_1.raw.zip	Raw
	F114ABAX_10min_2.raw.zip	Raw
	F114ABAX_10sec_1.raw.zip	Raw
	F114ABAX_10sec_2.raw.zip	Raw
	F114ABAX_1min_1.raw.zip	Raw