title: Crystal structure of a BRAF kinase domain monomer explains basis for allosteric regulation.
abstract: Reported RAF kinase domain structures adopt a side-to-side dimer configuration reflective of an 'on' state that underpins an allosteric mechanism of regulation. Atomic details of the monomer 'off' state have been elusive. Reinspection of the BRAF kinase domain structures revealed that sulfonamide inhibitors induce features of an off state, primarily a laterally displaced helix αC stabilized by the activation segment helix 1 (AS-H1). These features correlated with the ability of sulfonamides to disrupt human BRAF homodimers in cells, in vitro and in crystals yielding a structure of BRAF in a monomer state. The crystal structure revealed exaggerated, nonproductive positions of helix αC and AS-H1, the latter of which is the target of potent BRAF oncogenic mutations. Together, this work provides formal proof of an allosteric link between the RAF dimer interface, the activation segment and the catalytic infrastructure.
authors.affiliation: 1] Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada. [2] Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Neroshan
authors.initials: N
authors.lastname: Thevakumaran
authors.affiliation: Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Hugo
authors.initials: H
authors.lastname: Lavoie
authors.affiliation: Molecular Structure &Design Group, Molecular Discovery Technologies Department, Bristol-Myers Squibb Research, Princeton, New Jersey, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Critton
authors.affiliation: Molecular Structure &Design Group, Molecular Discovery Technologies Department, Bristol-Myers Squibb Research, Princeton, New Jersey, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Tebben
authors.affiliation: Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Marinier
authors.affiliation: 1] Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada. [2] Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada. [3] Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Frank
authors.initials: F
authors.lastname: Sicheri
authors.affiliation: 1] Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec, Canada. [2] Département de Pathologie et Biologie Cellulaire, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Therrien
mesh_terms: D000494:Allosteric Regulation; D006801:Humans; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization / Q000187:drug effects; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D013449:Sulfonamides / Q000378:metabolism
chemical_list: D013449:Sulfonamides; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf