title: Influence of the Compatible Solute Ectoine on the Local Water Structure: Implications for the Binding of the Protein G5P to DNA.
abstract: Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-5-protein (G5P) to a single-stranded DNA (dT25). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonucleotide, which has important consequences for osmotic regulation mechanisms.
authors.affiliation: Federal Institute for Materials Research and Testing , D-12205 Berlin, Germany.|Department of Physics, Free University Berlin , D-14195 Berlin, Germany.
authors.forename: Marc Benjamin
authors.initials: MB
authors.lastname: Hahn
authors.affiliation: Federal Institute for Materials Research and Testing , D-12205 Berlin, Germany.
authors.forename: Tihomir
authors.initials: T
authors.lastname: Solomun
authors.affiliation: Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytic and Bioprocesses , D-14476 Potsdam-Golm, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Wellhausen
authors.affiliation: Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytic and Bioprocesses , D-14476 Potsdam-Golm, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Hermann
authors.affiliation: Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytic and Bioprocesses , D-14476 Potsdam-Golm, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Seitz
authors.affiliation: Federal Institute for Materials Research and Testing , D-12205 Berlin, Germany.|Institute of Biochemistry and Biology, University of Potsdam , D-14476 Potsdam, Germany.
authors.forename: Susann
authors.initials: S
authors.lastname: Meyer
authors.affiliation: Federal Institute for Materials Research and Testing , D-12205 Berlin, Germany.
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Kunte
authors.affiliation: Institute for Computational Physics, University of Stuttgart , D-70569 Stuttgart, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Zeman
authors.affiliation: Institute for Computational Physics, University of Stuttgart , D-70569 Stuttgart, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Uhlig
authors.affiliation: Institute for Computational Physics, University of Stuttgart , D-70569 Stuttgart, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Smiatek
authors.affiliation: Federal Institute for Materials Research and Testing , D-12205 Berlin, Germany.|Technical University Berlin , D-10587 Berlin, Germany.
authors.forename: Heinz
authors.initials: H
authors.lastname: Sturm
mesh_terms: D000599:Amino Acids, Diamino / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D011485:Protein Binding; D013059:Spectrum Analysis, Raman; D020349:Surface Plasmon Resonance; D014867:Water / Q000737:chemistry
chemical_list: D000599:Amino Acids, Diamino; D014867:Water; C045628:ectoine