Structural basis of nSH2 regulation and lipid binding in PI3Kα

摘要: // Michelle S. Miller 1,8 , Oleg Schmidt-Kittler 2,9,12 David M. Bolduc 3,10 Evan T. Brower 2,11 Daniele Chaves-Moreira 4 Marc Allaire 7 Kenneth W. Kinzler 2 Ian G. Jennings 1 Philip E. Thompson A. Cole 3 L. Mario Amzel Bert Vogelstein and Sandra B. Gabelli 4,5,6 Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria, Australia. Ludwig Center for Cancer Genetics Therapeutics Howard Hughes Medical Institutions, Johns Hopkins University School Medicine, Baltimore, Maryland, USA. Department Pharmacology Molecular Biophysics Biophysical 5 6 Oncology, Photon Brookhaven National Laboratory, Upton, New York, 8 Present Address: Baltimore 9 Sanofi, Cambridge, Massachusetts. 10 Neurologic Diseases, Brigham Women’s Hospital Harvard School, Boston, 11 Paragon Bioservices, Maryland. 12 Berkeley Structural Biology, Physical Biosciences Division, Lawrence Berkeley, California. Correspondence: Gabelli, email: Keywords : PIK3R1, p85, PIK3CA, PI3K, PIP2, PIP3 Received June 23, 2014 Accepted July Published 25, Abstract We report two crystal structures the wild-type phosphatidylinositol 3-kinase α (PI3Kα) heterodimer refined to 2.9 A 3.4 resolution: first as free enzyme, second in complex with lipid substrate, diC4-PIP respectively. The structure shows key interactions N-terminal SH2 domain (nSH2) iSH2 activation loop that suggest a mechanism by which enzyme is inhibited its basal state. In structure, substrate binds positively charged pocket adjacent ATP-binding site, bordered P-loop, domain. An additional lipid-binding site was identified at interface ABD, kinase domains. ability PI3Kα bind an PIP molecule confirmed vitro fluorescence quenching experiments. reveal differences way nSH2 interacts p110α oncogenic mutant p110αH1047R. Increased buried surface area unique salt-bridges observed only tighter inhibition than mutant. These may be partially responsible increased activity membrane binding