The Photophobic Response of Various Sulfur and Nonsulfur Purple Bacteria

Hustede, E.; Liebergesell, Matthias; Schlegel, H. G.

doi:10.1111/j.1751-1097.1989.tb02912.x

Cited by 17 publications

(10 citation statements)

References 27 publications

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“…response in this species, which was demonstrated by the accumulation of free-swimming bacteria in light spots projected into the suspension (this work) and by reversible migration into the light in a glass capillary partly covered with foil (17), correlates its wavelength dependence with the absorption spectrum of the photosynthetic pigments, as in Rhodospirillum rubrum (5). In addition, positive phototaxis in E. halophila was effective at a much lower light intensity than the negative phototactic response, which is in agreement with the observation that most purple sulfur bacteria, including members of the genus Ectothiorhodospira, show maximal positive phototactic sensitivity at 40 mW of white light m-2 (12). In order to determine the wavelength dependence of the negative phototactic response in E. halophila for comparison, light intensities between 14 and 23 W m-2 were used.…”

Section: Discussionsupporting

confidence: 73%

“…Subsequently, it was demonstrated that upon absorption of a photon, the protein enters a photocycle in which a long-lived photointermediate absorbing in the near UV decays thermally to the ground state on the seconds time scale (half-life = 0.7 s [22] halophila. It was known that E. halophila, like all motile purple phototrophic bacteria studied so far, shows a normal positive photophobic response to photosynthetically active light (2,12,17). In this report, we present evidence indicating that E. halophila, in addition, shows a repellent response at physiological light intensities.…”

supporting

confidence: 55%

“…This organism exhibits a negative photophobic response to blue light between 400 and 500 nm. In contrast to the positive photophobic response that has been demonstrated for all motile purple bacteria studied so far (12), this negative response consists of an induction of reversals after an increase in blue light and suppression after a decrease in blue light. The latter effect, suppression of directional switches, has not yet been assessed in positive phototaxis for purple bacteria, although there is some evidence that this may occur (2).…”

Section: Discussionmentioning

confidence: 79%

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The eubacterium Ectothiorhodospira halophila is negatively phototactic, with a wavelength dependence that fits the absorption spectrum of the photoactive yellow protein

et al. 1993

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, Proc. Natl. Acad. Sci. USA 86:6533-6537, 1989; also, this work). In this study, we demonstrated that E. halophila is also negatively phototactic. Video analysis of free-swimming bacteria and the formation of cell distribution patterns as a result of light-color boundaries in an anaerobic suspension of cells revealed the existence of a repellent response toward intense (but nondamaging) blue light. In the presence of saturating background photosynthetic light, an increase in the intensity of blue light induced directional switches, whereas a decrease in intense blue light gave rise to suppression of these reversals. To our knowledge, this is the first report of a true repellent response to light in a free-swimming eubacterium, since the blue light response in Escherichia coli and Salmonella typhimurium (B. L. Taylor and D. E. Koshland, Jr., J. Bacteriol. 123:557-569, 1975), which requires an extremely high light intensity, is unlikely to be a sensory process. The wavelength dependence of this negative photoresponse was determined with narrow band pass interference filters. It showed similarity to the absorption spectrum of the photoactive yellow protein from E. halophila.In free-swimming prokaryotes, behavior at the molecular level involves the measurement of the value of certain chemical or physical parameters in the course of time, as the cell swims in spatial gradients of stimulants and/or repellents (for reviews, see references 2 and 7). Protein molecules with a sensory function, either chemo-or photoreceptors or specific indicators of cellular metabolism, such as the chemiosmotic proton gradient or the pool of certain metabolic intermediates, inform the cell about its present physiological situation. This information is compared with a previously sensed situation, and the change is evaluated as either favorable or unfavorable. Whereas the direction of the swimming of the cell with respect to the spatial gradient is random and remains so, uninfluenced by tactic processes, the time during which the cell continues swimming in a given direction is dependent on whether the integrated sensory signals are positive or negative. In the former case, the cell's tendency to switch its direction is suppressed, whereas in the latter case (i.e., when the sum is negative), it is enhanced.The process of chemotaxis in Escherichia coli has been extensively studied (2,7

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Section: Discussionsupporting

confidence: 73%

supporting

confidence: 55%

Section: Discussionmentioning

confidence: 79%

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The eubacterium Ectothiorhodospira halophila is negatively phototactic, with a wavelength dependence that fits the absorption spectrum of the photoactive yellow protein

et al. 1993

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“…For this study, we focused our attention on photoactive yellow protein (PYP), a 14-kDa water-soluble blue-light receptor first discovered in Halorhodospira halophila (4), a purple sulfur bacterium that swims away from blue light and toward photosynthetically useful green light (5,6). Because its action spectrum for negative phototaxis matches the absorbance spectrum of PYP (6), this protein is presumed responsible for the signal that causes this extreme halophile to swim away from photons energetic enough to be genetically harmful.…”

mentioning

confidence: 99%

Watching a signaling protein function in real time via 100-ps time-resolved Laue crystallography

Schotte

Cho

Kaila

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

179

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To understand how signaling proteins function, it is crucial to know the time-ordered sequence of events that lead to the signaling state. We recently developed on the BioCARS 14-IDB beamline at the Advanced Photon Source the infrastructure required to characterize structural changes in protein crystals with near-atomic spatial resolution and 150-ps time resolution, and have used this capability to track the reversible photocycle of photoactive yellow protein (PYP) following trans-to-cis photoisomerization of its p-coumaric acid (pCA) chromophore over 10 decades of time. The first of four major intermediates characterized in this study is highly contorted, with the pCA carbonyl rotated nearly 90°out of the plane of the phenolate. A hydrogen bond between the pCA carbonyl and the Cys69 backbone constrains the chromophore in this unusual twisted conformation. Density functional theory calculations confirm that this structure is chemically plausible and corresponds to a strained cis intermediate. This unique structure is short-lived (∼600 ps), has not been observed in prior cryocrystallography experiments, and is the progenitor of intermediates characterized in previous nanosecond time-resolved Laue crystallography studies. The structural transitions unveiled during the PYP photocycle include trans/cis isomerization, the breaking and making of hydrogen bonds, formation/ relaxation of strain, and gated water penetration into the interior of the protein. This mechanistically detailed, near-atomic resolution description of the complete PYP photocycle provides a framework for understanding signal transduction in proteins, and for assessing and validating theoretical/computational approaches in protein biophysics.time-resolved X-ray diffraction | photoreceptor | light sensor

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“…(termed by other authors "photophobotaxis"). If swimming cells experience diminishing light intensities, they stop and reverse their swimming direction, whereby Chromatium cells effectively accumulate at optimal irradiance (15,16,38). A combined effect of chemotaxis and photoresponses can be observed under the microscope.…”

mentioning

confidence: 99%