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Elife. 2017 Jun 8;6. pii: e25541. doi: 10.7554/eLife.25541.

Epistatic mutations in PUMA BH3 drive an alternate binding mode to potently and selectively inhibit anti-apoptotic Bfl-1.

Author information

1
Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.
2
Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, United States.
3
Department of Biology, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States.

Abstract

Overexpression of anti-apoptotic Bcl-2 family proteins contributes to cancer progression and confers resistance to chemotherapy. Small molecules that target Bcl-2 are used in the clinic to treat leukemia, but tight and selective inhibitors are not available for Bcl-2 paralog Bfl-1. Guided by computational analysis, we designed variants of the native BH3 motif PUMA that are > 150-fold selective for Bfl-1 binding. The designed peptides potently trigger disruption of the mitochondrial outer membrane in cells dependent on Bfl-1, but not in cells dependent on other anti-apoptotic homologs. High-resolution crystal structures show that designed peptide FS2 binds Bfl-1 in a shifted geometry, relative to PUMA and other binding partners, due to a set of epistatic mutations. FS2 modified with an electrophile reacts with a cysteine near the peptide-binding groove to augment specificity. Designed Bfl-1 binders provide reagents for cellular profiling and leads for developing enhanced and cell-permeable peptide or small-molecule inhibitors.

KEYWORDS:

apoptosis; binding specificity; biochemistry; biophysics; human; protein-protein interaction; structural biology

PMID:
28594323
PMCID:
PMC5464773
DOI:
10.7554/eLife.25541
[Indexed for MEDLINE]
Free PMC Article

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