title: "DFG-flip" in the insulin receptor kinase is facilitated by a helical intermediate state of the activation loop.
abstract: We have characterized a large-scale inactive-to-active conformational change in the activation-loop of the insulin receptor kinase domain at the atomistic level via untargeted temperature-accelerated molecular dynamics (TAMD) and free-energy calculations using the string method. TAMD simulations consistently show folding of the A-loop into a helical conformation followed by unfolding to an active conformation, causing the highly conserved DFG-motif (Asp(1150), Phe(1151), and Gly(1152)) to switch from the inactive "D-out/F-in" to the nucleotide-binding-competent "D-in/F-out" conformation. The minimum free-energy path computed from the string method preserves these helical intermediates along the inactive-to-active path, and the thermodynamic free-energy differences are consistent with previous work on various other kinases. The mechanisms revealed by TAMD also suggest that the regulatory spine can be dynamically assembled/disassembled either by DFG-flip or by movement of the αC-helix. Together, these findings both broaden our understanding of kinase activation and point to intermediates as specific therapeutic targets.
authors: Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan, USA.
authors: Harish
authors: H
authors: Vashisth
authors: Luca
authors: L
authors: Maragliano
authors: Cameron F
authors: CF
authors: Abrams
mesh_terms: D020816:Amino Acid Motifs; D004789:Enzyme Activation; D056004:Molecular Dynamics Simulation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism*; D011972:Receptor, Insulin / Q000737:chemistry* / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D014443:Tyrosine
chemical_list: D012997:Solvents; D014443:Tyrosine; D011972:Receptor, Insulin; D017346:Protein Serine-Threonine Kinases; C081827:insulin receptor serine kinase