Phototaxis and Impaired Motility in Adenylyl Cyclase and Cyclase Receptor Protein Mutants of<i>Synechocystis</i>sp. Strain PCC 6803

Bhaya, Devaki; Nakasugi, Kenlee; Fazeli, Fariba; Burriesci, Matthew S.

doi:10.1128/jb.00573-06

Cited by 41 publications

(40 citation statements)

References 31 publications

(40 reference statements)

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“…These spectrum-specific photoresponses support the current view that the cAMPCrp complex is ecologically beneficial for optimal positioning of motile cells relative to incident light (Bhaya et al, 2006;Masuda & Ono, 2004). Indeed, it has been shown that intracellular cAMP is necessary and sufficient to restore phototactic motility used by cells to escape from the confines of a colony during suboptimal illumination (Bhaya et al, 2006;Terauchi & Ohmori, 1999).…”

supporting

confidence: 74%

Illumination stimulates cAMP receptor protein-dependent transcriptional activation from regulatory regions containing class I and class II promoter elements in Synechocystis sp. PCC 6803

et al. 2009

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The cAMP receptor protein (Crp) is a global transcriptional regulator that binds sequence-specific promoter elements when associated with cAMP. In the motile cyanobacterium Synechocystis sp. strain PCC 6803, intracellular cAMP increases when dark-adapted cells are illuminated. Previous work has established that Crp binds proposed Crp target sites upstream of slr1351 (murF), sll1874 (chlA II ), sll1708 (narL), slr0442 and sll1268 in vitro, and that slr0442 is downregulated in a crp mutant during photoautotrophic growth. To identify additional Crp target genes in Synechocystis, 11 different Crp binding sites proposed during a previous computational survey were tested for in vitro sequence-specific binding and crp-dependent transcription. The results indicate that murF, chlA II and slr0442 can be added as 'target genes of Sycrp1' in Synechocystis. Promoter mapping of the targets revealed the same close association of RNA polymerase and Crp as that found in Escherichia coli class I and class II Crp-regulated promoters, thereby strongly suggesting similar mechanisms of transcriptional activation.

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supporting

confidence: 74%

Illumination stimulates cAMP receptor protein-dependent transcriptional activation from regulatory regions containing class I and class II promoter elements in Synechocystis sp. PCC 6803

et al. 2009

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“…Similarly, in this work, non-motile Dhfq mutant cells were also not rescued by cAMP addition (data not shown). However, there seems to be an important difference between Dsycrp1 and Dhfq mutant cells, that is to say motility of sycrp1 disruptants is affected only in the 'strong' phototaxis characterized by projections on the agar plate, while individual cells still appear motile (Bhaya et al, 2006).…”

Section: Discussionmentioning

confidence: 97%

The cyanobacterial homologue of the RNA chaperone Hfq is essential for motility of Synechocystis sp. PCC 6803

et al. 2008

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“…This surface-dependent phototaxis is mediated by Type IV pili (12)(13)(14). In addition, several components of the signal transduction pathway including photoreceptors have been identified using mutant screens and biochemical analyses (5,(15)(16)(17)(18)(19). It has been suggested that cells sense light direction rather than flux (7), but we have limited understanding of how this information is sensed and transduced to Type IV pili to cause directional motility.…”

Section: Introductionmentioning

confidence: 99%

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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Phototaxis and Impaired Motility in Adenylyl Cyclase and Cyclase Receptor Protein Mutants ofSynechocystissp. Strain PCC 6803

Cited by 41 publications

References 31 publications

Illumination stimulates cAMP receptor protein-dependent transcriptional activation from regulatory regions containing class I and class II promoter elements in Synechocystis sp. PCC 6803

Illumination stimulates cAMP receptor protein-dependent transcriptional activation from regulatory regions containing class I and class II promoter elements in Synechocystis sp. PCC 6803

The cyanobacterial homologue of the RNA chaperone Hfq is essential for motility of Synechocystis sp. PCC 6803

Maintenance of Motility Bias during Cyanobacterial Phototaxis

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