title: Neutron scattering reveals extremely slow cell water in a Dead Sea organism.
abstract: Intracellular water dynamics in Haloarcula marismortui, an extremely halophilic organism originally isolated from the Dead Sea, was studied by neutron scattering. The water in centrifuged cell pellets was examined by means of two spectrometers, IN6 and IN16, sensitive to motions with time scales of 10 ps and 1 ns, respectively. From IN6 data, a translational diffusion constant of 1.3 x 10(-5) cm(2) s(-1) was determined at 285 K. This value is close to that found previously for other cells and close to that for bulk water, as well as that of the water in the 3.5 M NaCl solution bathing the cells. A very slow water component was discovered from the IN16 data. At 285 K the water-protons of this component displays a residence time of 411 ps (compared with a few ps in bulk water). At 300 K, the residence time dropped to 243 ps and was associated with a translational diffusion of 9.3 x 10(-8) cm(2) s(-1), or 250 times lower than that of bulk water. This slow water accounts for approximately 76% of cell water in H. marismortui. No such water was found in Escherichia coli measured on BSS, a neutron spectrometer with properties similar to those of IN16. It is hypothesized that the slow mobility of a large part of H. marismortui cell water indicates a specific water structure responsible for the large amounts of K(+) bound within these extremophile cells.
authors.affiliation: Institut de Biologie Structurale, Commissariat à l'Energie Atomique-Centre National de la Recherche Scientifique-Université Joseph Fourier, Laboratoire de Biophysique Moléculaire, 41 Rue Jules Horowitz, 38027 Grenoble Cedex 1, France.
authors.forename: Moeava
authors.initials: M
authors.lastname: Tehei
authors.forename: Bruno
authors.initials: B
authors.lastname: Franzetti
authors.forename: Kathleen
authors.initials: K
authors.lastname: Wood
authors.forename: Frank
authors.initials: F
authors.lastname: Gabel
authors.forename: Elisa
authors.initials: E
authors.lastname: Fabiani
authors.forename: Marion
authors.initials: M
authors.lastname: Jasnin
authors.forename: Michaela
authors.initials: M
authors.lastname: Zamponi
authors.forename: Dieter
authors.initials: D
authors.lastname: Oesterhelt
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zaccai
authors.forename: Margaret
authors.initials: M
authors.lastname: Ginzburg
authors.forename: Ben-Zion
authors.initials: BZ
authors.lastname: Ginzburg
mesh_terms: D004926:Escherichia coli; D019614:Haloarcula marismortui / Q000166:cytology*; D007424:Intracellular Fluid / Q000737:chemistry*; D007557:Israel; D007597:Jordan; D033363:Neutron Diffraction; D009502:Neutrons; D009792:Oceans and Seas; D011189:Potassium Chloride; D012965:Sodium Chloride; D012996:Solutions; D013057:Spectrum Analysis; D013997:Time Factors; D014867:Water / Q000032:analysis* / Q000737:chemistry
chemical_list: D012996:Solutions; D014867:Water; D012965:Sodium Chloride; D011189:Potassium Chloride