Evaluation of Diverse Alpha/Beta-Backbone Patterns for Functional Alpha-Helix Mimicry: Analogues of the Bim Bh3 Domain.Boersma, M.D., Haase, H.S., Peterson-Kaufman, K.J., Lee, E.F., Clarke, O.B., Colman, P.M., Smith, B.J., Horne, W.S., Fairlie, W.D., Gellman, S.H.
(2012) J.Am.Chem.Soc. 134: 315
- PubMed: 22040025
- DOI: 10.1021/ja207148m
- Primary Citation of Related Structures:
- PubMed Abstract:
Peptidic oligomers that contain both α- and β-amino acid residues, in regular patterns throughout the backbone, are emerging as structural mimics of α-helix-forming conventional peptides (composed exclusively of α-amino acid residues). Here we descri ...
Peptidic oligomers that contain both α- and β-amino acid residues, in regular patterns throughout the backbone, are emerging as structural mimics of α-helix-forming conventional peptides (composed exclusively of α-amino acid residues). Here we describe a comprehensive evaluation of diverse α/β-peptide homologues of the Bim BH3 domain in terms of their ability to bind to the BH3-recognition sites on two partner proteins, Bcl-x(L) and Mcl-1. These proteins are members of the anti-apoptotic Bcl-2 family, and both bind tightly to the Bim BH3 domain itself. All α/β-peptide homologues retain the side-chain sequence of the Bim BH3 domain, but each homologue contains periodic α-residue → β(3)-residue substitutions. Previous work has shown that the ααβαααβ pattern, which aligns the β(3)-residues in a 'stripe' along one side of the helix, can support functional α-helix mimicry, and the results reported here strengthen this conclusion. The present study provides the first evaluation of functional mimicry by ααβ and αααβ patterns, which cause the β(3)-residues to spiral around the helix periphery. We find that the αααβ pattern can support effective mimicry of the Bim BH3 domain, as manifested by the crystal structure of an α/β-peptide bound to Bcl-x(L), affinity for a variety of Bcl-2 family proteins, and induction of apoptotic signaling in mouse embryonic fibroblast extracts. The best αααβ homologue shows substantial protection from proteolytic degradation relative to the Bim BH3 α-peptide.
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.