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Identification of the first structurally validated covalent ligands of the small GTPase RAB27A

DOI: 10.1039/D1MD00225B DOI Help

Authors: Mostafa Jamshidiha (Imperial College London) , Thomas Lanyon-Hogg (Imperial College London) , Charlotte L. Sutherell (Imperial College London) , Gregory B. Craven (Imperial College London) , Montse Tersa (Imperial College London) , Elena De Vita (Imperial College London) , Delia Brustur (Imperial College London) , Inmaculada Perez-Dorado (Imperial College London) , Sarah Hassan (Imperial College London) , Rita Petracca (Imperial College London) , Rhodri M. Morgan (Imperial College London) , Máximo Sanz-Hernández (Imperial College London) , Jim C. Norman (Beatson Institute for Cancer Research) , Alan Armstrong (Imperial College London) , David J. Mann (Imperial College London) , Ernesto Cota (Imperial College London) , Edward W. Tate (Imperial College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Rsc Medicinal Chemistry , VOL 22

State: Published (Approved)
Published: December 2021
Diamond Proposal Number(s): 17221 , 23620

Open Access Open Access

Abstract: Rab27A is a small GTPase, which mediates transport and docking of secretory vesicles at the plasma membrane via protein–protein interactions (PPIs) with effector proteins. Rab27A promotes the growth and invasion of multiple cancer types such as breast, lung and pancreatic, by enhancing secretion of chemokines, metalloproteases and exosomes. The significant role of Rab27A in multiple cancer types and the minor role in adults suggest that Rab27A may be a suitable target to disrupt cancer metastasis. Similar to many GTPases, the flat topology of the Rab27A-effector PPI interface and the high affinity for GTP make it a challenging target for inhibition by small molecules. Reported co-crystal structures show that several effectors of Rab27A interact with the Rab27A SF4 pocket (‘WF-binding pocket’) via a conserved tryptophan–phenylalanine (WF) dipeptide motif. To obtain structural insight into the ligandability of this pocket, a novel construct was designed fusing Rab27A to part of an effector protein (fRab27A), allowing crystallisation of Rab27A in high throughput. The paradigm of KRas covalent inhibitor development highlights the challenge presented by GTPase proteins as targets. However, taking advantage of two cysteine residues, C123 and C188, that flank the WF pocket and are unique to Rab27A and Rab27B among the >60 Rab family proteins, we used the quantitative Irreversible Tethering (qIT) assay to identify the first covalent ligands for native Rab27A. The binding modes of two hits were elucidated by co-crystallisation with fRab27A, exemplifying a platform for identifying suitable lead fragments for future development of competitive inhibitors of the Rab27A-effector interaction interface, corroborating the use of covalent libraries to tackle challenging targets.

Subject Areas: Biology and Bio-materials, Chemistry, Medicine

Instruments: I02-Macromolecular Crystallography

Added On: 27/12/2021 16:56


Discipline Tags:

Non-Communicable Diseases Health & Wellbeing Cancer Biochemistry Chemistry Drug Discovery Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)