Selective affimers recognize the BCL‐2 family proteins BCL‐xL and MCL‐1 through non‐canonical structural motifs

DOI: 10.1002/cbic.202000585

Authors: Jennifer Miles (University of Leeds) , Fruzsina Hobor (University of Leeds) , Chi Trinh (University of Leeds) , James Taylor (University of Leeds) , Christian Tiede (University of Leeds) , Philip Rowell (University of Leeds) , Brian Jackson (University of Leeds) , Fatima Nadat (University of Leeds) , Pallavi Ramsahye (University of Leeds) , Hannah Kyle (University of Leeds) , Basile Wicky (University of Cambridge) , Jane Clarke (University of Cambridge) , Darren Tomlinson (University of Leeds) , Andrew Wilson (University of Leeds) , Thomas Edwards (University of Leeds)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chembiochem

State: Published (Approved)
Published: September 2020
Diamond Proposal Number(s): 10305

Abstract: The BCL‐2 family is a challenging group of proteins to target selectively due to sequence and structural homologies across the family. Selective ligands for the BCL‐2 family regulators of apoptosis are useful as probes to understand cell biology and apoptotic signalling pathways, and as starting points for inhibitor design. We have used phage display to isolate Affimer reagents (non‐antibody binding proteins based on a conserved scaffold) to identify ligands for MCL‐1, BCL‐xL, BCL‐2, BAK and BAX, then used multiple biophysical characterisation methods to probe the interactions. We established that purified Affimers elicit selective recognition of their target BCL‐2 protein. For anti‐apoptotic targets BCL‐xL and MCL‐1, competitive inhibition of their canonical protein‐protein interactions is demonstrated. Co‐crystal structures reveal an unprecedented mode of molecular recognition; where a BH3 helix is normally bound, flexible loops from the Affimer dock into the BH3 binding cleft. Moreover, the Affimers induce a change in the target proteins towards a desirable drug bound like conformation. These proof of concept studies indicate that Affimers could be used as alternative templates to inspire design of selective BCL‐2 family modulators and more generally other protein‐protein interaction inhibitors.

Journal Keywords: Affimers; PPIs; Bcl; Mcl

Subject Areas: Biology and Bio-materials, Chemistry


Instruments: I04-1-Macromolecular Crystallography (fixed wavelength)

Documents:
cbic.202000585.pdf

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