Phototropin is the blue-light receptor that controls multiple steps in the sexual life cycle of the green alga
            <i>Chlamydomonas</i>
            <i>reinhardtii</i>

Huang, Kaiyao; Beck, Christoph F.

doi:10.1073/pnas.0931459100

Cited by 189 publications

(170 citation statements)

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“…They thus might be expected to share similar mechanisms for light sensing and retrograde signaling. However, many chlorophyte genomes lack phytochromes (21-24), a deficiency offset by a larger complement of flavin-and retinal-based sensors (25)(26)(27)(28)(29)(30).…”

Section: Rna-seq Analysismentioning

confidence: 99%

Retrograde bilin signaling enables Chlamydomonas greening and phototrophic survival

Duanmu

Casero

Dent

et al. 2013

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

111

172

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The maintenance of functional chloroplasts in photosynthetic eukaryotes requires real-time coordination of the nuclear and plastid genomes. Tetrapyrroles play a significant role in plastid-tonucleus retrograde signaling in plants to ensure that nuclear gene expression is attuned to the needs of the chloroplast. Well-known sites of synthesis of chlorophyll for photosynthesis, plant chloroplasts also export heme and heme-derived linear tetrapyrroles (bilins), two critical metabolites respectively required for essential cellular activities and for light sensing by phytochromes. Here we establish that Chlamydomonas reinhardtii, one of many chlorophyte species that lack phytochromes, can synthesize bilins in both plastid and cytosol compartments. Genetic analyses show that both pathways contribute to iron acquisition from extracellular heme, whereas the plastid-localized pathway is essential for light-dependent greening and phototrophic growth. Our discovery of a bilin-dependent nuclear gene network implicates a widespread use of bilins as retrograde signals in oxygenic photosynthetic species. Our studies also suggest that bilins trigger critical metabolic pathways to detoxify molecular oxygen produced by photosynthesis, thereby permitting survival and phototrophic growth during the light period.biliverdin | heme oxygenase | iron homeostasis | oxidative stress | RNA-Seq analysisT he daily light-dark cycle requires all oxygenic photosynthetic species to survive the repeated transition from prolonged darkness to phototrophic metabolism at dawn. Most plants are unable to synthesize chlorophyll in darkness and therefore accumulate photosensitizing chlorophyll precursors at night (1). Sunrise induces an oxidative burst as photosynthesis resumes, so the transition to daylight requires careful coordination of many lightdependent processes. Multiple photoreceptors perform such roles in plants, the most notable being the red-sensing, linear tetrapyrrole (bilin)-based phytochromes and the blue-sensing, flavin-based cryptochromes and phototropins (2-5). Bilins are well-established plant retrograde signals, synthesized in plastids but enabling light sensing by cytosolic phytochromes. Phytochrome photoconversion then triggers nuclear translocation to positively regulate photosynthesis-associated nuclear gene (PhANG) expression (6, 7).Genetic studies suggest that plastids also export negative retrograde signals, metabolites that suppress nuclear gene networks targeted by phytochromes (8-10). Among these metabolites are abscisic acid (ABA) (11), tetrapyrroles (12-14), 3′-phosphoadenosine 5′-phosphate (PAP) (15), β-cyclocitral (16), and methylerythritol cyclodiphosphate (MEcPP) (17). Although hypothetical export of a negative tetrapyrrole signal has received considerable support, biochemical evidence for such a retrograde signal remains equivocal in plants (18)(19)(20). Chlorophyte algae diverged from the streptophyte plant lineage over 500 million years ago but share a common chlorophyll a/b-based photosynthetic lightharvesting app...

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Section: Rna-seq Analysismentioning

confidence: 99%

Retrograde bilin signaling enables Chlamydomonas greening and phototrophic survival

Duanmu

Casero

Dent

et al. 2013

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

111

172

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“…Therefore, we will pay particular attention on photoreceptors of these two species. The unicellular alga C. reinhardtii is a widely recognized model organism for the investigation of biological processes including photosynthesis and light-dependent physiological and behavioral responses (Berthold et al 2008;Foster et al 1984;Huang and Beck 2003;Rochaix 2002). However, the confusing maze behind the individual activities of photoreceptors in the multicellular alga V. carteri will help us to understand the link between light and complex light-affected cellular processes such as cellular differentiation (Kirk and Kirk 1985), which have been required for evolutionary transition from unicellular organisms into a multicellular one (Kirk 2005).…”

Section: Introductionmentioning

confidence: 99%

Algal photoreceptors: in vivo functions and potential applications

Kianianmomeni

Hallmann

2013

Planta

107

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“…Specifically, Chlamydomonas possesses a single phototropin (Huang and Beck, 2003), rhodopsins, including channelrhodopsins (Nagel et al, 2002(Nagel et al, , 2003Kateriya et al, 2004), a plant-like cryptochrome (Reisdorph and Small, 2004), and an animal-like cryptochrome that responds to both blue and red light (Beel et al, 2012). Furthermore, a histidine kinase rhodopsin was recently characterized that exists in both UV-A-and blue-light-absorbing isoforms (Luck et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

UV-B Perception and Acclimation in Chlamydomonas reinhardtii

et al. 2016

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Plants perceive UV-B, an intrinsic component of sunlight, via a signaling pathway that is mediated by the photoreceptor UV RESISTANCE LOCUS8 (UVR8) and induces UV-B acclimation. To test whether similar UV-B perception mechanisms exist in the evolutionarily distant green alga Chlamydomonas reinhardtii, we identified Chlamydomonas orthologs of UVR8 and the key signaling factor CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). Cr-UVR8 shares sequence and structural similarity to Arabidopsis thaliana UVR8, has conserved tryptophan residues for UV-B photoreception, monomerizes upon UV-B exposure, and interacts with Cr-COP1 in a UV-B-dependent manner. Moreover, Cr-UVR8 can interact with At-COP1 and complement the Arabidopsis uvr8 mutant, demonstrating that it is a functional UV-B photoreceptor. Chlamydomonas shows apparent UV-B acclimation in colony survival and photosynthetic efficiency assays. UV-B exposure, at low levels that induce acclimation, led to broad changes in the Chlamydomonas transcriptome, including in genes related to photosynthesis. Impaired UV-B-induced activation in the Cr-COP1 mutant hit1 indicates that UVR8-COP1 signaling induces transcriptome changes in response to UV-B. Also, hit1 mutants are impaired in UV-B acclimation. Chlamydomonas UV-B acclimation preserved the photosystem II core proteins D1 and D2 under UV-B stress, which mitigated UV-B-induced photoinhibition. These findings highlight the early evolution of UVR8 photoreceptor signaling in the green lineage to induce UV-B acclimation and protection.

show abstract

Phototropin is the blue-light receptor that controls multiple steps in the sexual life cycle of the green alga Chlamydomonas reinhardtii

Cited by 189 publications

References 50 publications

Retrograde bilin signaling enables Chlamydomonas greening and phototrophic survival

Retrograde bilin signaling enables Chlamydomonas greening and phototrophic survival

Algal photoreceptors: in vivo functions and potential applications

UV-B Perception and Acclimation in Chlamydomonas reinhardtii

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