title: The dark recovery rate in the photocycle of the bacterial photoreceptor YtvA is affected by the cellular environment and by hydration.
abstract: We report thermal recovery kinetics of the lit state into the parental dark state, measured for the blue light-sensing photoreceptor YtvA inside overexpressing E. coli and B. subtilis bacterial cells, performed for the wild type and several mutated proteins. Recovery was followed as a recovery of the fluorescence, as this property is only found for the parental but not for the photochemically generated lit state. When cells were deposited onto a microscope glass plate, the observed thermal recovery rate in the photocycle was found ca. ten times faster in comparison to purified YtvA in solution. When the E. coli or B. subtilis colonies were soaked in an isotonic buffer, the dark relaxation became again much slower and was very similar to that observed for YtvA in solution. The observed effects show that rate constants can be tuned by the cellular environment through factors such as hydration.
authors.affiliation: Fondazione Istituto Italiano di Tecnologia, Genova, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Pennacchietti
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università di Parma, Parma, Italy; NEST, Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Abbruzzetti
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università di Parma, Parma, Italy.
authors.forename: Aba
authors.initials: A
authors.lastname: Losi
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università di Parma, Parma, Italy.
authors.forename: Carmen
authors.initials: C
authors.lastname: Mandalari
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università di Parma, Parma, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Bedotti
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università di Parma, Parma, Italy; NEST, Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: Cristiano
authors.initials: C
authors.lastname: Viappiani
authors.affiliation: Fondazione Istituto Italiano di Tecnologia, Genova, Italy.
authors.forename: Francesca Cella
authors.initials: FC
authors.lastname: Zanacchi
authors.affiliation: Fondazione Istituto Italiano di Tecnologia, Genova, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Diaspro
authors.affiliation: Max-Planck-Institute for Chemical Energy Conversion (CEC), Mülheim a.d. Ruhr, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Gärtner
mesh_terms: D001412:Bacillus subtilis; D001426:Bacterial Proteins / Q000737:chemistry* / Q000502:physiology; D003890:Desiccation; D007700:Kinetics; D008027:Light; D055668:Photochemical Processes; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000502:physiology*; D014867:Water / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; D014867:Water