Blue Light Signaling Chains in Phycomyces: Phototransduction of Carotenogenesis and Morphogenesis Involves Distinct Protein Kinase/Phosphatase Elements

Tsolakis, George; Parashi, Eleni; Galland, Paul; Kotzabasis, Kiriakos

doi:10.1006/fgbi.1999.1175

Cited by 12 publications

(8 citation statements)

References 45 publications

(36 reference statements)

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“…The action spectra for the high and low fluence responses of photomacrophorogenesis and photomicrophorogenesis suggest different but related photoreceptors, perhaps even four different receptors (Corrochano et al, 1988). A recent study has shown that the kinase inhibitor staurosporine can replace the effect of light in photophorogenesis (Tsolakis et al, 1999), suggesting that a kinase is inhibited during light signaling in photophorogenesis.…”

Section: Discussionmentioning

confidence: 99%

Role of Nitric Oxide Synthase in the Light-Induced Development of Sporangiophores in Phycomyces blakesleeanus

et al. 2001

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Blue light controls the development of sporangiophores in the zygomycete Phycomyces blakesleeanus Burgeff. Light represses the production of microsporangiophores and enhances the development of macrosporangiophores. Inhibition of the biosynthesis of tetrahydrobiopterin, a cofactor of NO synthase, inhibits this photomorphogenesis. Light induces production of citrulline from arginine in the mycelium and in sporangiophores. The citrulline-forming activity is dependent on NADPH, independent of calcium, and inhibited by NO synthase inhibitors. It is reduced in tetrahydrobiopterin-depleted mycelium. Light induces emission of NO from the developing fungus in the same order of magnitude as citrulline formation from arginine. The NO donor sodium nitroprusside can replace the light effect on sporangiophore development, and inhibitors of NO synthase repress it. We suggest that a fungal NO synthase is involved in sporangiophore development and propose its participation in light signaling.

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Section: Discussionmentioning

confidence: 99%

Role of Nitric Oxide Synthase in the Light-Induced Development of Sporangiophores in Phycomyces blakesleeanus

et al. 2001

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“…p-Carotene extractions were applied in mycelia either 72 h after the inoculation of dishes (treatments with analogues) or 24 h after mycelia filtration and transfemng onto minimal plates (experiments with toxins), according to the extraction protocol by Tsolakis eta[. (30).…”

Section: Methodsmentioning

confidence: 99%

“…Morphogenesis assays. The dry weight of macrophores and the mean microphore density per square millimeter per culture dish were determined either 96 h after the inoculation of plates (experiments with analogues) or 72 h after mycelia filtration and plate transfemng (toxin treatments with stating liquid cultures), as described before (30).…”

Section: Methodsmentioning

confidence: 99%

Involvement of G Proteins in the Mycelial Photoresponses of Phycomyces

Tsolakis¹,

Moschonas²,

Galland³

et al. 2004

Photchem. Photbio.

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Many responses of the zygomycete fungus Phycomyces blakesleeanus are mediated by blue light, e.g. the stimulation of p-carotene synthesis (photocarotenogenesis) and the formation of fruiting bodies (photomorphogenesis). Even though both responses have been described in detail genetically and biophysically, the underlying molecular events remain unknown. Applying a pharmacological approach in developing mycelia, we investigated the possible involvement of heterotrimeric G proteins in the blue-light transduction chains of both responses. G protein agonists (guanosine triphosphate analogues, cholera toxin, pertussis toxin) mimicked in darkness the effect of blue light for both responses, except for cholera toxin, which was ineffective in increasing the pcarotene content of dark-grown mycelia. Experiments combining the two toxins indicated that photocarotenogenesis could involve an inhibitory G protein (Gi) type, whereas photomorphogenesis may depend on a transducin (G, type)like heterotrimer. The determination of the carB (phytoene dehydrogenase) and chsl (chitin synthase 1) gene expression under various conditions of exogenous challenge supports the G protein participation. The fluctuations of the time course measurements of the carB and chsZ transcripts are discussed.

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“…Carotenogenesis is also less sensitive to light in other mutants, such as picA and picB [ 62 ], specifi cally affected in this response, or pimA , altered as well in photomorphogenesis [ 64 ]. These mutants might be affected in a signal transduction cascade involving phosphorylation events [ 65 ], connecting light detection and biochemical or developmental responses.…”

Section: Activation By Lightmentioning

confidence: 96%