Structural and dynamic insights into the energetics of activation loop rearrangement in FGFR1 kinase

• Published in: Nature communications Vol. 6; no. 1; p. 7877
• Main Authors: Klein, Tobias, Vajpai, Navratna, Phillips, Jonathan J., Davies, Gareth, Holdgate, Geoffrey A., Phillips, Chris, Tucker, Julie A., Norman, Richard A., Scott, Andrew D., Higazi, Daniel R., Lowe, David, Thompson, Gary S., Breeze, Alexander L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.07.2015; Nature Publishing Group; Nature Pub. Group
• Subjects: 101/58; 101/6; 631/45/535; 631/45/607/275; 631/57/1464; 631/92/56; 82/103; Enzymes; Escherichia coli; Humanities and Social Sciences; Humans; Imidazoles; Kinases; Kinetics; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular biology; Molecular Structure; multidisciplinary; NMR; Nuclear magnetic resonance; Pathogenesis; Proteins; Pyridazines; Receptor, Fibroblast Growth Factor, Type 1 - antagonists & inhibitors; Receptor, Fibroblast Growth Factor, Type 1 - metabolism; Science; Science (multidisciplinary); United Kingdom > UK
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms8877

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. Receptor tyrosine kinases are key mediators of cell proliferation that have been implicated in several disease states for which they represent promising drug targets. Here the authors determine the thermodynamic basis for the low propensity of FGFR1 to access the DFG-Phe-out conformation required to bind type-II inhibitors.