title: Transient non-native hydrogen bonds promote activation of a signaling protein.
abstract: Phosphorylation is a common mechanism for activating proteins within signaling pathways. Yet, the molecular transitions between the inactive and active conformational states are poorly understood. Here we quantitatively characterize the free-energy landscape of activation of a signaling protein, nitrogen regulatory protein C (NtrC), by connecting functional protein dynamics of phosphorylation-dependent activation to protein folding and show that only a rarely populated, pre-existing active conformation is energetically stabilized by phosphorylation. Using nuclear magnetic resonance (NMR) dynamics, we test an atomic scale pathway for the complex conformational transition, inferred from molecular dynamics simulations (Lei et al., 2009). The data show that the loss of native stabilizing contacts during activation is compensated by non-native transient atomic interactions during the transition. The results unravel atomistic details of native-state protein energy landscapes by expanding the knowledge about ground states to transition landscapes.
authors.affiliation: Department of Biochemistry and Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02452, USA.
authors.forename: Alexandra K
authors.initials: AK
authors.lastname: Gardino
authors.forename: Janice
authors.initials: J
authors.lastname: Villali
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Kivenson
authors.forename: Ming
authors.initials: M
authors.lastname: Lei
authors.forename: Ce Feng
authors.initials: CF
authors.lastname: Liu
authors.forename: Phillip
authors.initials: P
authors.lastname: Steindel
authors.forename: Elan Z
authors.initials: EZ
authors.lastname: Eisenmesser
authors.forename: Wladimir
authors.initials: W
authors.lastname: Labeikovsky
authors.forename: Magnus
authors.initials: M
authors.lastname: Wolf-Watz
authors.forename: Michael W
authors.initials: MW
authors.lastname: Clarkson
authors.forename: Dorothee
authors.initials: D
authors.lastname: Kern
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D019906:Nuclear Magnetic Resonance, Biomolecular; D051922:PII Nitrogen Regulatory Proteins / Q000378:metabolism*; D011487:Protein Conformation; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D051922:PII Nitrogen Regulatory Proteins