Oligomerization of BH4-truncated Bcl-x(L) in solution.
BH4 domain is critical for the anti-apoptotic functions of Bcl-2 and Bcl-x(L) and their binding abilities with other members of the Bcl-2 family. The cleavage of the BH4 domain in Bcl-x(L) and Bcl-2 by caspase 1 or 3 converts the anti-apoptotic Bcl-x(L) and Bcl-2 into pro-apoptotic proteins that potently induce apoptosis. Herein, we report that recombinant Bcl-x(L) proteins without N-terminal 61 residues, His(6)-NDelta61-Bcl-x(L)-CDelta21 and NDelta61-Bcl-x(L)-CDelta21, form oligomers in solution, whereas Bcl-x(L)-CDelta21 exists as a monomer. The oligomerization of the truncated proteins is independent of protein-lipid interaction, protein concentration or the ion strength of the solution. Circular dichroism spectrum shows a significant decrease in the content of alpha-helices upon deletion of N-terminal residues. NDelta61-Bcl-x(L)-CDelta21 also loses its heterodimerization capability with the BH3 peptide derived from Bak. This newly acquired property might be linked to its ability to induce apoptosis in cells.
Wang
Youli
Y
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Cao
Rong
R
Liu
Dongxiang
D
Chervin
Adam
A
Yuan
Jian
J
An
Jing
J
Huang
Ziwei
Z
D002942:Circular Dichroism; D019281:Dimerization; D008027:Light; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry; D012542:Scattering, Radiation; D017384:Sequence Deletion; D012996:Solutions; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D012996:Solutions; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein