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

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Title: Identification of the first structurally validated covalent ligands of the small GTPase RAB27A
Authors: Jamshidiha, M
Lanyon-Hogg, T
Sutherell, C
Craven, G
Tersa, M
De Vita, E
Brustur, D
Perez-Doraldo, I
Hassan, S
Petracca, R
Morgan, R
Sanz-Hernández, M
Norman, J
Armstrong, A
Mann, D
Cota, E
Tate, E
Item Type: Journal Article
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.
Issue Date: 16-Dec-2021
Date of Acceptance: 6-Dec-2021
URI: http://hdl.handle.net/10044/1/93207
DOI: 10.1039/d1md00225b
ISSN: 2632-8682
Publisher: Royal Society of Chemistry
Start Page: 150
End Page: 155
Journal / Book Title: RSC Medicinal Chemistry
Volume: 13
Issue: 2
Copyright Statement: © The Royal Society of Chemistry 2021. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (https://creativecommons.org/licenses/by/3.0/)
Sponsor/Funder: Cancer Research UK
Commission of the European Communities
Commission of the European Communities
Cancer Research UK
Funder's Grant Number: 20781
Keywords: Science & Technology
Life Sciences & Biomedicine
Biochemistry & Molecular Biology
Chemistry, Medicinal
Pharmacology & Pharmacy
Publication Status: Published
Online Publication Date: 2021-12-16
Appears in Collections:Chemistry
Biological and Biophysical Chemistry
Faculty of Natural Sciences

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