title: Conformational analysis of Epac activation using amide hydrogen/deuterium exchange mass spectrometry.
abstract: Exchange proteins directly activated by cAMP (Epac) play important roles in mediating the effects of cAMP through the activation of downstream small GTPases, Rap. To delineate the mechanism of Epac activation, we probed the conformation and structural dynamics of Epac using amide hydrogen/deuterium exchange and structural modeling. Our studies show that cAMP induces significant conformational changes that lead to a spatial rearrangement of the regulatory components of Epac and allows the exposure of the catalytic core for effector binding without imposing significant conformational change on the catalytic core. Homology modeling and comparative structural analyses of the cAMP binding domains of Epac and cAMP-dependent protein kinase (PKA) lead to a model of Epac activation, in which Epac and PKA activation by cAMP employs the same underlying principle, although the detailed structural and conformational changes associated with Epac and PKA activation are significantly different.
authors.affiliation: Department of Pharmacology and Toxicology and Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555-1031, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Brock
authors.forename: Fenghui
authors.initials: F
authors.lastname: Fan
authors.forename: Fang C
authors.initials: FC
authors.lastname: Mei
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
authors.forename: Christopher
authors.initials: C
authors.lastname: Gessner
authors.forename: Virgil L
authors.initials: VL
authors.lastname: Woods
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Cheng
mesh_terms: D000595:Amino Acid Sequence; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism; D041961:Deuterium Exchange Measurement; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism