title: mRNA display selection of a high-affinity, Bcl-X(L)-specific binding peptide.
abstract: Bcl-X(L), an antiapoptotic member of the Bcl-2 family, is a mitochondrial protein that inhibits activation of Bax and Bak, which commit the cell to apoptosis, and it therefore represents a potential target for drug discovery. Peptides have potential as therapeutic molecules because they can be designed to engage a larger portion of the target protein with higher specificity. In the present study, we selected 16-mer peptides that interact with Bcl-X(L) from random and degenerate peptide libraries using mRNA display. The selected peptides have sequence similarity with the Bcl-2 family BH3 domains, and one of them has higher affinity (IC(50)=0.9 microM) than Bak BH3 (IC(50)=11.8 microM) for Bcl-X(L) in vitro. We also found that GFP fusions of the selected peptides specifically interact with Bcl-X(L), localize in mitochondria, and induce cell death. Further, a chimeric molecule, in which the BH3 domain of Bak protein was replaced with a selected peptide, retained the ability to bind specifically to Bcl-X(L). These results demonstrate that this selected peptide specifically antagonizes the function of Bcl-X(L) and overcomes the effects of Bcl-X(L) in intact cells. We suggest that mRNA display is a powerful technique to identify peptide inhibitors with high affinity and specificity for disease-related proteins.
authors.affiliation: Department of Biosciences and Informatics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Matsumura
authors.forename: Toru
authors.initials: T
authors.lastname: Tsuji
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sumida
authors.forename: Masahito
authors.initials: M
authors.lastname: Kokubo
authors.forename: Michiko
authors.initials: M
authors.lastname: Onimaru
authors.forename: Nobuhide
authors.initials: N
authors.lastname: Doi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Takashima
authors.forename: Etsuko
authors.initials: E
authors.lastname: Miyamoto-Sato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yanagawa
mesh_terms: D016923:Cell Death / Q000187:drug effects; D015723:Gene Library; D006801:Humans; D008928:Mitochondria; D019151:Peptide Library; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D012333:RNA, Messenger; D051020:bcl-X Protein / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D019151:Peptide Library; D010455:Peptides; D012333:RNA, Messenger; D051020:bcl-X Protein