The Role of Cyanopterin in UV/Blue Light Signal Transduction of Cyanobacterium Synechocystis sp. PCC 6803 Phototaxis

Moon, Yoon-Jung; Lee, Eun-Mi; Park, Young Mok; Park, Young Shik; Chung, Woosuk; Chung, Young‐Ho

doi:10.1093/pcp/pcq059

Cited by 38 publications

(38 citation statements)

References 45 publications

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“…This method also permits analysis of key mutants in terms of changes in the motility of single cells, thereby expanding on previous studies that relied on qualitative characteristics of community behavior (8,12,13,18,23,25,29). Here, we demonstrate that heterogeneous behavior exists across spatial locations in the community; cells in finger-like projections displayed higher motility bias and a decreased fraction of nonmotile cells.…”

Section: Introductionsupporting

confidence: 50%

“…Some of the photoreceptors also have overlapping absorption spectra such that they absorb at approximately the same wavelengths as each other (e.g., TaxD1 and PixD at 435 nm, and TaxD1 and UirS at 535 nm) (18,24,25). Previous studies of the behavior of mutants have established the role of each photoreceptor in either positive or negative phototaxis (7,8,18,29,30). The first photoreceptor identified to play a role in phototaxis was TaxD1, a cyanobacteriochrome that exists in two photo-reversible states, a blue light-absorbing form and a green light-absorbing form (24,31).…”

Section: Introductionmentioning

confidence: 99%

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Maintenance of Motility Bias during Cyanobacterial Phototaxis

Chau

Ursell

Wang

et al. 2015

Biophysical Journal

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Signal transduction in bacteria is complex, ranging across scales from molecular signal detectors and effectors to cellular and community responses to stimuli. The unicellular, photosynthetic cyanobacterium Synechocystis sp. PCC6803 transduces a light stimulus into directional movement known as phototaxis. This response occurs via a biased random walk toward or away from a directional light source, which is sensed by intracellular photoreceptors and mediated by Type IV pili. It is unknown how quickly cells can respond to changes in the presence or directionality of light, or how photoreceptors affect single-cell motility behavior. In this study, we use time-lapse microscopy coupled with quantitative single-cell tracking to investigate the timescale of the cellular response to various light conditions and to characterize the contribution of the photoreceptor TaxD1 (PixJ1) to phototaxis. We first demonstrate that a community of cells exhibits both spatial and population heterogeneity in its phototactic response. We then show that individual cells respond within minutes to changes in light conditions, and that movement directionality is conferred only by the current light directionality, rather than by a long-term memory of previous conditions. Our measurements indicate that motility bias likely results from the polarization of pilus activity, yielding variable levels of movement in different directions. Experiments with a photoreceptor (taxD1) mutant suggest a supplementary role of TaxD1 in enhancing movement directionality, in addition to its previously identified role in promoting positive phototaxis. Motivated by the behavior of the taxD1 mutant, we demonstrate using a reaction-diffusion model that diffusion anisotropy is sufficient to produce the observed changes in the pattern of collective motility. Taken together, our results establish that single-cell tracking can be used to determine the factors that affect motility bias, which can then be coupled with biophysical simulations to connect changes in motility behaviors at the cellular scale with group dynamics.

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Section: Introductionsupporting

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Maintenance of Motility Bias during Cyanobacterial Phototaxis

Chau

Ursell

Wang

et al. 2015

Biophysical Journal

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“…Apart from their UV-C-UV-Babsorbing characteristics, pterin and flavin coenzymes are known to be photochemically active chromophores in a number of actual photoenzymes and sensory photoreceptor proteins (Kritsky et al, 1997(Kritsky et al, , 2010, suggesting a continuity of function since their first appearance near the origin of life. Examples are pterin-and flavin-based photoreceptor proteins called cryptochromes and phototropins in plants which mediate plant phototropism (Brautigam et al, 2004) and the pigment cyanopterin which functions as a UV/blue photoreceptor in cyanobacterial phototaxis (Moon et al, 2010). The cofactor component of these photoreceptor proteins is actually responsible for the absorption of incident visible and UV photons and they have even been proposed as ancient prechlorophyll photosynthetic pigments (Kritsky et al, 2013a, b).…”

Section: K Michaelian and A Simeonov: Fundamental Molecules Of Lifementioning

confidence: 99%

Fundamental molecules of life are pigments which arose and co-evolved as a response to the thermodynamic imperative of dissipating the prevailing solar spectrum

Michaelian

Simeonov²

2015

Biogeosciences

112

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Abstract. The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short-wavelength UV-C and UV-B dissipation. On Earth's surface, water and organic pigments in water facilitate the near-UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UV-C and UV-B that could have reached Earth's surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by (1) increasing the ratio of their effective photon cross sections to their physical size, (2) decreasing their electronic excited state lifetimes, (3) quenching radiative de-excitation channels (e.g., fluorescence), (4) covering ever more completely the prevailing solar spectrum, and (5) proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth's atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose, proliferated, and co-evolved as a response to dissipating the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth's early atmosphere, and sheds some new light on the origin of photosynthesis.

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“…Although light avoidance is regulated by sensory rhodopsins in Archaea and in a few proteobacterial and algal species (4), no such proteins are encoded within the Synechocystis genome. Known photosensors that play key roles in Synechocystis phototaxis include the phytochrome-related cyanobacteriochromes (CBCRs) PixJ1/TaxD1 (5,6) and Cph2 (7), the BLUF photosensor PixD (8) and the CRY-related cyanopterin Sll1629 (9). Despite new insight into the regulatory roles of these proteins in UV-mediated phototaxis in Synechocystis (10), photoreceptors that directly sense unidirectional UV are unknown.…”

mentioning

confidence: 99%

Near-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803

Song

Cho

et al. 2011

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

156

238

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Positive phototaxis systems have been well studied in bacteria; however, the photoreceptor(s) and their downstream signaling components that are responsible for negative phototaxis are poorly understood. Negative phototaxis sensory systems are important for cyanobacteria, oxygenic photosynthetic organisms that must contend with reactive oxygen species generated by an abundance of pigment photosensitizers. The unicellular cyanobacterium Synechocystis sp. PCC6803 exhibits type IV pilus-dependent negative phototaxis in response to unidirectional UV-A illumination. Using a reverse genetic approach, together with biochemical, molecular genetic, and RNA expression profiling analyses, we show that the cyanobacteriochrome locus ( slr1212/uirS ) of Synechocystis and two adjacent response regulator loci ( slr1213/uirR and the PatA-type regulator slr1214/lsiR ) encode a UV-A–activated signaling system that is required for negative phototaxis. We propose that UirS, which is membrane-associated via its ETR1 domain, functions as a UV-A photosensor directing expression of lsiR via release of bound UirR, which targets the lsiR promoter. Constitutive expression of LsiR induces negative phototaxis under conditions that normally promote positive phototaxis. Also induced by other stresses, LsiR thus integrates light inputs from multiple photosensors to determine the direction of movement.

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The Role of Cyanopterin in UV/Blue Light Signal Transduction of Cyanobacterium Synechocystis sp. PCC 6803 Phototaxis

Cited by 38 publications

References 45 publications

Maintenance of Motility Bias during Cyanobacterial Phototaxis

Maintenance of Motility Bias during Cyanobacterial Phototaxis

Fundamental molecules of life are pigments which arose and co-evolved as a response to the thermodynamic imperative of dissipating the prevailing solar spectrum

Near-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803

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