The dark recovery rate in the photocycle of the bacterial photoreceptor YtvA is affected by the cellular environment and by hydration

• Published in: PloS one Vol. 9; no. 9; p. e107489
• Main Authors: Pennacchietti, Francesca, Abbruzzetti, Stefania, Losi, Aba, Mandalari, Carmen, Bedotti, Roberta, Viappiani, Cristiano, Zanacchi, Francesca Cella, Diaspro, Alberto, Gärtner, Wolfgang
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11.09.2014; Public Library of Science (PLoS)
• Subjects: Bacillus subtilis; Bacterial Proteins - chemistry; Bacterial Proteins - physiology; Biochemistry; Biology and Life Sciences; Chlamydomonas reinhardtii; Desiccation; E coli; Escherichia coli; Experiments; Fluorescence; Gene expression; Glass plates; Hydration; Kinetics; Light; Lymphocytes B; Microscopy; Parenting; Photochemical Processes; Photoreceptors; Photoreceptors, Microbial - chemistry; Photoreceptors, Microbial - physiology; Proteins; Rate constants; Recovery; Recovery (Medical); Water - chemistry; Italy; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0107489

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.