title: Structural and dynamic insights into the energetics of activation loop rearrangement in FGFR1 kinase.
abstract: Protein tyrosine kinases differ widely in their propensity to undergo rearrangements of the N-terminal Asp-Phe-Gly (DFG) motif of the activation loop, with some, including FGFR1 kinase, appearing refractory to this so-called 'DFG flip'. Recent inhibitor-bound structures have unexpectedly revealed FGFR1 for the first time in a 'DFG-out' state. Here we use conformationally selective inhibitors as chemical probes for interrogation of the structural and dynamic features that appear to govern the DFG flip in FGFR1. Our detailed structural and biophysical insights identify contributions from altered dynamics in distal elements, including the αH helix, towards the outstanding stability of the DFG-out complex with the inhibitor ponatinib. We conclude that the αC-β4 loop and 'molecular brake' regions together impose a high energy barrier for this conformational rearrangement, and that this may have significance for maintaining autoinhibition in the non-phosphorylated basal state of FGFR1.
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.
authors.forename: Tobias
authors.initials: T
authors.lastname: Klein
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.
authors.forename: Navratna
authors.initials: N
authors.lastname: Vajpai
authors.affiliation: MedImmune, Granta Park, Cambridge CB21 6GH, UK.
authors.forename: Jonathan J
authors.identifier: http://orcid.org/0000-0002-5361-9582
authors.initials: JJ
authors.lastname: Phillips
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.
authors.forename: Gareth
authors.initials: G
authors.lastname: Davies
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Holdgate
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Phillips
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Tucker
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Norman
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Scott
authors.affiliation: MedImmune, Granta Park, Cambridge CB21 6GH, UK.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Higazi
authors.affiliation: MedImmune, Granta Park, Cambridge CB21 6GH, UK.
authors.forename: David
authors.initials: D
authors.lastname: Lowe
authors.affiliation: Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Thompson
authors.affiliation: Discovery Sciences, AstraZeneca R&D, Alderley Park, Macclesfield SK10 4TG, UK.|Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Breeze
mesh_terms: D004926:Escherichia coli; D006801:Humans; D007093:Imidazoles; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D011724:Pyridazines; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D007093:Imidazoles; D011724:Pyridazines; C545373:ponatinib; C496348:FGFR1 protein, human; D051496:Receptor, Fibroblast Growth Factor, Type 1