title: Neutron scattering measurements of intact cells show changes after heat shock consistent with an increase in molecular crowding.
abstract: Molecular crowding has been shown to be important in many cellular processes. The crowded environment in the cell results in a significant proportion of the cellular water being in contact with macromolecules such as proteins and DNA. These interfacial water molecules show a reduced dynamic motion that has been observed with isolated macromolecules using several biophysical techniques. Previously we investigated the inelastic neutron scattering properties of water closely associated with isolated biomolecules, and showed that interfacial water is strongly perturbed, as judged by its energy transfer spectrum. Here we have probed living cells using inelastic and quasielastic neutron scattering. We have found that mild heat stress ('heat shock'), which causes some proteins to become unfolded in the cell, results in changes in the inelastic neutron scattering in the librational region (45-130 meV). Heat shock also causes a narrowing of the quasielastic scattering peak. These changes can be understood in terms of an increase in the proportion of interfacial water molecules, and a net reduction in proton dynamics.
authors.affiliation: Department of Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD, UK. r.ford@umist.ac.uk
authors.forename: Robert C
authors.initials: RC
authors.lastname: Ford
authors.forename: Stuart V
authors.initials: SV
authors.lastname: Ruffle
authors.forename: Ilias
authors.initials: I
authors.lastname: Michalarias
authors.forename: Ilir
authors.initials: I
authors.lastname: Beta
authors.forename: Anibal J
authors.initials: AJ
authors.lastname: Ramirez-Cuesta
authors.forename: Jichen
authors.initials: J
authors.lastname: Li
mesh_terms: D004058:Diffusion; D004735:Energy Transfer; D018869:Heat-Shock Response; D009502:Neutrons; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D012542:Scattering, Radiation; D014867:Water / Q000737:chemistry
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D014867:Water