I03-Macromolecular Crystallography
I04-Macromolecular Crystallography
|
Xiangrong
Chen
,
Yusuf I
Ali
,
Charlotte E. L.
Fisher
,
Raquel
Arribas-Bosacoma
,
Mohan B.
Rajasekaran
,
Gareth
Williams
,
Sarah
Walker
,
Jessica R.
Booth
,
Jessica J R.
Hudson
,
S. Mark
Roe
,
Laurence H.
Pearl
,
Simon E.
Ward
,
Frances M G.
Pearl
,
Antony W.
Oliver
Diamond Proposal Number(s):
[20145]
Open Access
Abstract: BLM (Bloom syndrome protein) is a RECQ-family helicase involved in the dissolution of complex DNA structures and repair intermediates. Synthetic lethality analysis implicates BLM as a promising target in a range of cancers with defects in the DNA damage response; however, selective small molecule inhibitors of defined mechanism are currently lacking. Here, we identify and characterise a specific inhibitor of BLM’s ATPase-coupled DNA helicase activity, by allosteric trapping of a DNA-bound translocation intermediate. Crystallographic structures of BLM-DNA-ADP-inhibitor complexes identify a hitherto unknown interdomain interface, whose opening and closing are integral to translocation of ssDNA, and which provides a highly selective pocket for drug discovery. Comparison with structures of other RECQ helicases provides a model for branch migration of Holliday junctions by BLM.
|
Mar 2021
|
|
I24-Microfocus Macromolecular Crystallography
|
Angeliki
Ditsiou
,
Chiara
Cilibrasi
,
Nikiana
Simigdala
,
Athanasios
Papakyriakou
,
Leanne
Milton-Harris
,
Viviana
Vella
,
Joanne E.
Nettleship
,
Jae Ho
Lo
,
Shivani
Soni
,
Goar
Smbatyan
,
Panagiota
Ntavelou
,
Teresa
Gagliano
,
Maria Chiara
Iachini
,
Sahir
Khurshid
,
Thomas
Simon
,
Lihong
Zhou
,
Storm
Hassell-Hart
,
Philip
Carter
,
Laurence H.
Pearl
,
Robin L.
Owen
,
Raymond J.
Owens
,
S. Mark
Roe
,
Naomi E.
Chayen
,
Heinz-Josef
Lenz
,
John
Spencer
,
Chrisostomos
Prodromou
,
Apostolos
Klinakis
,
Justin
Stebbing
,
Georgios
Giamas
Diamond Proposal Number(s):
[14493]
Open Access
Abstract: Elucidating signaling driven by lemur tyrosine kinase 3 (LMTK3) could help drug development. Here, we solve the crystal structure of LMTK3 kinase domain to 2.1Å resolution, determine its consensus motif and phosphoproteome, unveiling in vitro and in vivo LMTK3 substrates. Via high-throughput homogeneous time-resolved fluorescence screen coupled with biochemical, cellular, and biophysical assays, we identify a potent LMTK3 small-molecule inhibitor (C28). Functional and mechanistic studies reveal LMTK3 is a heat shock protein 90 (HSP90) client protein, requiring HSP90 for folding and stability, while C28 promotes proteasome-mediated degradation of LMTK3. Pharmacologic inhibition of LMTK3 decreases proliferation of cancer cell lines in the NCI-60 panel, with a concomitant increase in apoptosis in breast cancer cells, recapitulating effects of LMTK3 gene silencing. Furthermore, LMTK3 inhibition reduces growth of xenograft and transgenic breast cancer mouse models without displaying systemic toxicity at effective doses. Our data reinforce LMTK3 as a druggable target for cancer therapy.
|
Nov 2020
|
|
I03-Macromolecular Crystallography
I04-Macromolecular Crystallography
|
Diamond Proposal Number(s):
[10088]
Open Access
Abstract: Coordination of the cellular response to DNA damage is organised by multi-domain 'scaffold' proteins, including 53BP1 and TOPBP1, which recognise post-translational modifications such as phosphorylation, methylation and ubiquitylation on other proteins, and are themselves carriers of such regulatory signals. Here we show that the DNA damage checkpoint regulating S-phase entry is controlled by a phosphorylation-dependent interaction of 53BP1 and TOPBP1. BRCT domains of TOPBP1 selectively bind conserved phosphorylation sites in the N-terminus of 53BP1. Mutation of these sites does not affect formation of 53BP1 or ATM foci following DNA damage, but abolishes recruitment of TOPBP1, ATR and CHK1 to 53BP1 damage foci, abrogating cell cycle arrest and permitting progression into S-phase. TOPBP1 interaction with 53BP1 is structurally complimentary to its interaction with RAD9-RAD1-HUS1, allowing these damage recognition factors to bind simultaneously to the same TOPBP1 molecule and cooperate in ATR activation in the G1 DNA damage checkpoint.
|
May 2019
|
|
I02-Macromolecular Crystallography
|
Open Access
Abstract: TOPBP1 and its fission yeast homologue Rad4, are critical players in a range of DNA replication, repair and damage signalling processes. They are composed of multiple BRCT domains, some of which bind phosphorylated motifs in other proteins. They thus act as multi-point adaptors bringing proteins together into functional combinations, dependent on post-translational modifications downstream of cell cycle and DNA damage signals. We have now structurally and/or biochemically characterised a sufficient number of high-affinity complexes for the conserved N-terminal region of TOPBP1 and Rad4 with diverse phospho-ligands, including human RAD9 and Treslin, and Schizosaccharomyces pombe Crb2 and Sld3, to define the determinants of BRCT domain specificity. We use this to identify and characterise previously unknown phosphorylation-dependent TOPBP1/Rad4-binding motifs in human RHNO1 and the fission yeast homologue of MDC1, Mdb1. These results provide important insights into how multiple BRCT domains within TOPBP1/Rad4 achieve selective and combinatorial binding of their multiple partner proteins.
|
Oct 2018
|
|
Krios I-Titan Krios I at Diamond
|
Fabrizio
Martino
,
Mohinder
Pal
,
Hugo
Muñoz-Hernández
,
Carlos F.
Rodríguez
,
Rafael
Núñez-Ramírez
,
David
Gil-Carton
,
Gianluca
Degliesposti
,
J. Mark
Skehel
,
Mark
Roe
,
Chrisostomos
Prodromou
,
Laurence H.
Pearl
,
Oscar
Llorca
Diamond Proposal Number(s):
[13312, 13520, 15997]
Open Access
Abstract: The R2TP/Prefoldin-like co-chaperone, in concert with HSP90, facilitates assembly and cellular stability of RNA polymerase II, and complexes of PI3-kinase-like kinases such as mTOR. However, the mechanism by which this occurs is poorly understood. Here we use cryo-EM and biochemical studies on the human R2TP core (RUVBL1–RUVBL2–RPAP3–PIH1D1) which reveal the distinctive role of RPAP3, distinguishing metazoan R2TP from the smaller yeast equivalent. RPAP3 spans both faces of a single RUVBL ring, providing an extended scaffold that recruits clients and provides a flexible tether for HSP90. A 3.6 Å cryo-EM structure reveals direct interaction of a C-terminal domain of RPAP3 and the ATPase domain of RUVBL2, necessary for human R2TP assembly but absent from yeast. The mobile TPR domains of RPAP3 map to the opposite face of the ring, associating with PIH1D1, which mediates client protein recruitment. Thus, RPAP3 provides a flexible platform for bringing HSP90 into proximity with diverse client proteins.
|
Apr 2018
|
|
Krios I-Titan Krios I at Diamond
|
Diamond Proposal Number(s):
[13520, 14507]
Open Access
Abstract: The R2TP complex, comprising the Rvb1p-Rvb2p AAA-ATPases, Tah1p, and Pih1p in yeast, is a specialized Hsp90 co-chaperone required for the assembly and maturation of multi-subunit complexes. These include the small nucleolar ribonucleoproteins, RNA polymerase II, and complexes containing phosphatidylinositol-3-kinase-like kinases. The structure and stoichiometry of yeast R2TP and how it couples to Hsp90 are currently unknown. Here, we determine the 3D organization of yeast R2TP using sedimentation velocity analysis and cryo-electron microscopy. The 359-kDa complex comprises one Rvb1p/Rvb2p hetero-hexamer with domains II (DIIs) forming an open basket that accommodates a single copy of Tah1p-Pih1p. Tah1p-Pih1p binding to multiple DII domains regulates Rvb1p/Rvb2p ATPase activity. Using domain dissection and cross-linking mass spectrometry, we identified a unique region of Pih1p that is essential for interaction with Rvb1p/Rvb2p. These data provide a structural basis for understanding how R2TP couples an Hsp90 dimer to a diverse set of client proteins and complexes.
|
Jul 2017
|
|
I04-1-Macromolecular Crystallography (fixed wavelength)
|
Diamond Proposal Number(s):
[10088]
Open Access
Abstract: Tetratricopeptide (TPR) domains are known protein interaction domains. We show that the TPR domain of FKBP8 selectively binds Hsp90, and interactions upstream of the conserved MEEVD motif are critical for tight binding. In contrast FKBP8 failed to bind intact Hsp70. The PPIase domain was not essential for the interaction with Hsp90 and binding was completely encompassed by the TPR domain alone. The conformation adopted by Hsp90 peptides, containing the conserved MEEVD motif, in the crystal structure were similar to that seen for the TPR domains of CHIP, AIP and Tah1. The carboxylate clamp interactions with bound Hsp90 peptide were a critical component of the interaction and mutation of Lys 307, involved in the carboxylate clamp, completely disrupted the interaction with Hsp90. FKBP8 binding to Hsp90 did not substantially influence its ATPase activity.
|
Mar 2017
|
|
B21-High Throughput SAXS
I04-Macromolecular Crystallography
|
Aaron
Alt
,
Hung Q.
Dang
,
Owen S.
Wells
,
Luis M.
Polo
,
Matt A.
Smith
,
Grant A.
Mcgregor
,
Thomas
Welte
,
Alan R.
Lehmann
,
Laurence H.
Pearl
,
Johanne M.
Murray
,
Antony W.
Oliver
Diamond Proposal Number(s):
[10088, 6385]
Open Access
Abstract: The Structural Maintenance of Chromosomes (SMC) complexes: cohesin, condensin and Smc5/6 are involved in the organization of higher-order chromosome structure—which is essential for accurate chromosome duplication and segregation. Each complex is scaffolded by a specific SMC protein dimer (heterodimer in eukaryotes) held together via their hinge domains. Here we show that the Smc5/6-hinge, like those of cohesin and condensin, also forms a toroidal structure but with distinctive subunit interfaces absent from the other SMC complexes; an unusual ‘molecular latch’ and a functional ‘hub’. Defined mutations in these interfaces cause severe phenotypic effects with sensitivity to DNA-damaging agents in fission yeast and reduced viability in human cells. We show that the Smc5/6-hinge complex binds preferentially to ssDNA and that this interaction is affected by both ‘latch’ and ‘hub’ mutations, suggesting a key role for these unique features in controlling DNA association by the Smc5/6 complex.
|
Jan 2017
|
|
I04-Macromolecular Crystallography
|
Peter
Hornyak
,
T.
Askwith
,
S.
Walker
,
E.
Komulainen
,
M.
Paradowski
,
L. E.
Pennicott
,
E. J.
Bartlett
,
Nigel
Brissett
,
A.
Raoof
,
M.
Watson
,
A. M.
Jordan
,
D. J.
Ogilvie
,
S. E.
Ward
,
J. R.
Atack
,
Laurence
Pearl
,
K. W.
Caldecott
,
Antony W.
Oliver
Diamond Proposal Number(s):
[10088]
Open Access
Abstract: TDP2 is a 5'-tyrosyl DNA phosphodiesterase important for the repair of DNA adducts generated by non-productive (abortive) activity of topoisomerase II. TDP2 facilitates therapeutic resistance to topoisomerase poisons, which are widely used in the treatment of a range of cancer types. Consequently, TDP2 is an interesting target for the development of small molecule inhibitors that could restore sensitivity to topoisomerase-directed therapies. Previous studies identified a class of deazaflavin-based molecules that showed inhibitory activity against TDP2 at therapeutically useful concentrations, but their mode of action was uncertain. We have confirmed that the deazaflavin series inhibits TDP2 enzyme activity in a fluorescence-based assay, suitable for HTS-screening. We have gone on to determine crystal structures of these compounds bound to a 'humanised' form of murine TDP2. The structures reveal their novel mode of action as competitive ligands for the binding site of an incoming DNA substrate, and point the way to generating novel and potent inhibitors of TDP2.
|
Jun 2016
|
|
I04-Macromolecular Crystallography
|
Open Access
Abstract: 53BP1 plays multiple roles in mammalian DNA damage repair, mediating pathway choice and facilitating DNA double-strand break repair in heterochromatin. Although it possesses a C-terminal BRCT2 domain, commonly involved in phospho-peptide binding in other proteins, initial recruitment of 53BP1 to sites of DNA damage depends on interaction with histone post-translational modifications—H4K20me2 and H2AK13/K15ub—downstream of the early γH2AX phosphorylation mark of DNA damage. We now show that, contrary to current models, the 53BP1-BRCT2 domain binds γH2AX directly, providing a third post-translational mark regulating 53BP1 function. We find that the interaction of 53BP1 with γH2AX is required for sustaining the 53BP1-dependent focal concentration of activated ATM that facilitates repair of DNA double-strand breaks in heterochromatin in G1.
|
Nov 2015
|
|