Conformational changes and protein stability of the pro-apoptotic protein Bax.
Pro-apoptotic Bax is a soluble and monomeric protein under normal physiological conditions. Upon its activation substantial structural rearrangements occur: The protein inserts into the mitochondrial outer membrane and forms higher molecular weight oligomers. Subsequently, the cells can undergo apoptosis. In our studies, we focused on the structural rearrangements of Bax during oligomerization and on the protein stability. Both protein conformations exhibit high stability against thermal denaturation, chemically induced unfolding and proteolytic processing. The oligomeric protein is stable up to 90 degrees C as well as in solutions of 8 M urea or 6 M guanidinium hydrochloride. Helix 9 appears accessible in the monomer but hidden in the oligomer assessed by proteolysis. Tryptophan fluorescence indicates that the environment of the C-terminal protein half becomes more apolar upon oligomerization, whereas the loop region between helices 1 and 2 gets solvent exposed.
Bleicken
Stephanie
S
Department of Membrane Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
Zeth
Kornelius
K
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D019295:Computational Biology; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D055550:Protein Stability; D016415:Sequence Alignment; D013050:Spectrometry, Fluorescence; D051028:bcl-2-Associated X Protein / Q000235:genetics*
D051028:bcl-2-Associated X Protein