|
| ||
|
|
||
Blue-light Receptors (blue-light + receptor)
Selected AbstractsCHARACTERIZATION OF A DINOFLAGELLATE CRYPTOCHROME BLUE-LIGHT RECEPTOR WITH A POSSIBLE ROLE IN CIRCADIAN CONTROL OF THE CELL CYCLE,JOURNAL OF PHYCOLOGY, Issue 3 2007Stephanie A. Brunelle Karenia brevis (C. C. Davis) G. Hansen et Moestrup is a dinoflagellate responsible for red tides in the Gulf of Mexico. The signaling pathways regulating its cell cycle are of interest because they are the key to the formation of toxic blooms that cause mass marine animal die-offs and human illness. Karenia brevis displays phased cell division, in which cells enter S phase at precise times relative to the onset of light. Here, we demonstrate that a circadian rhythm underlies this behavior and that light quality affects the rate of cell-cycle progression: in blue light, K. brevis entered the S phase early relative to its behavior in white light of similar intensity, whereas in red light, K. brevis was not affected. A data base of 25,000 K. brevis expressed sequence tags (ESTs) revealed several sequences with similarity to cryptochrome blue-light receptors, but none related to known red-light receptors. We characterized the K. brevis cryptochrome (Kb CRY) and modeled its three-dimensional protein structure. Phylogenetic analysis of the photolyase/CRY gene family showed that Kb CRY is a member of the cryptochrome DASH (CRY DASH) clade. Western blotting with an antibody designed to bind a conserved peptide within Kb CRY identified a single band at ,55 kDa. Immunolocalization showed that Kb CRY, like CRY DASH in Arabidopsis, is localized to the chloroplast. This is the first blue-light receptor to be characterized in a dinoflagellate. As the Kb CRY appears to be the only blue-light receptor expressed, it is a likely candidate for circadian entrainment of the cell cycle. [source] Phototropins and Their LOV Domains: Versatile Plant Blue-Light ReceptorsJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 1 2007Winslow R. Briggs Abstract The phototropins phot1 and phot2 are plant blue-light receptors that mediate phototropism, chloroplast movements, stomatal opening, leaf expansion, the rapid inhibition of hypocotyl growth in etiolated seedlings, and possibly solar tracking by leaves in those species in which it occurs. The phototropins are plasma membrane-associated hydrophilic proteins with two chromophore domains (designated LOV1 and LOV2 for their resemblance to domains in other signaling proteins that detect light, oxygen, or voltage) in their N-terminal half and a classic serine/threonine kinase domain in their C-terminal half. Both chromophore domains bind flavin mononucleotide (FMN) and both undergo light-activated formation of a covalent bond between a nearby cysteine and the C(4a) carbon of the FMN to form the signaling state. LOV2-cysteinyl adduct formation leads to the release downstream of a tightly bound amphipathic ,-helix, a step required for activation of the kinase function. This cysteinyl adduct then slowly decays over a matter of seconds or minutes to return the photoreceptor chromophore modules to their ground state. Functional LOV2 is required for light-activated phosphorylation and for various blue-light responses mediated by the phototropins. The function of LOV1 is still unknown, although it may serve to modulate the signal generated by LOV2. The LOV domain is an ancient chromophore module found in a wide range of otherwise unrelated proteins in fungi and prokaryotes, the latter including cyanobacteria, eubacteria, and archaea. Further general reviews on the phototropins are those by Celaya and Liscum (2005) and Christie and Briggs (2005). [source] CHARACTERIZATION OF A DINOFLAGELLATE CRYPTOCHROME BLUE-LIGHT RECEPTOR WITH A POSSIBLE ROLE IN CIRCADIAN CONTROL OF THE CELL CYCLE,JOURNAL OF PHYCOLOGY, Issue 3 2007Stephanie A. Brunelle Karenia brevis (C. C. Davis) G. Hansen et Moestrup is a dinoflagellate responsible for red tides in the Gulf of Mexico. The signaling pathways regulating its cell cycle are of interest because they are the key to the formation of toxic blooms that cause mass marine animal die-offs and human illness. Karenia brevis displays phased cell division, in which cells enter S phase at precise times relative to the onset of light. Here, we demonstrate that a circadian rhythm underlies this behavior and that light quality affects the rate of cell-cycle progression: in blue light, K. brevis entered the S phase early relative to its behavior in white light of similar intensity, whereas in red light, K. brevis was not affected. A data base of 25,000 K. brevis expressed sequence tags (ESTs) revealed several sequences with similarity to cryptochrome blue-light receptors, but none related to known red-light receptors. We characterized the K. brevis cryptochrome (Kb CRY) and modeled its three-dimensional protein structure. Phylogenetic analysis of the photolyase/CRY gene family showed that Kb CRY is a member of the cryptochrome DASH (CRY DASH) clade. Western blotting with an antibody designed to bind a conserved peptide within Kb CRY identified a single band at ,55 kDa. Immunolocalization showed that Kb CRY, like CRY DASH in Arabidopsis, is localized to the chloroplast. This is the first blue-light receptor to be characterized in a dinoflagellate. As the Kb CRY appears to be the only blue-light receptor expressed, it is a likely candidate for circadian entrainment of the cell cycle. [source] Phototropins and Their LOV Domains: Versatile Plant Blue-Light ReceptorsJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 1 2007Winslow R. Briggs Abstract The phototropins phot1 and phot2 are plant blue-light receptors that mediate phototropism, chloroplast movements, stomatal opening, leaf expansion, the rapid inhibition of hypocotyl growth in etiolated seedlings, and possibly solar tracking by leaves in those species in which it occurs. The phototropins are plasma membrane-associated hydrophilic proteins with two chromophore domains (designated LOV1 and LOV2 for their resemblance to domains in other signaling proteins that detect light, oxygen, or voltage) in their N-terminal half and a classic serine/threonine kinase domain in their C-terminal half. Both chromophore domains bind flavin mononucleotide (FMN) and both undergo light-activated formation of a covalent bond between a nearby cysteine and the C(4a) carbon of the FMN to form the signaling state. LOV2-cysteinyl adduct formation leads to the release downstream of a tightly bound amphipathic ,-helix, a step required for activation of the kinase function. This cysteinyl adduct then slowly decays over a matter of seconds or minutes to return the photoreceptor chromophore modules to their ground state. Functional LOV2 is required for light-activated phosphorylation and for various blue-light responses mediated by the phototropins. The function of LOV1 is still unknown, although it may serve to modulate the signal generated by LOV2. The LOV domain is an ancient chromophore module found in a wide range of otherwise unrelated proteins in fungi and prokaryotes, the latter including cyanobacteria, eubacteria, and archaea. Further general reviews on the phototropins are those by Celaya and Liscum (2005) and Christie and Briggs (2005). [source] CHARACTERIZATION OF A DINOFLAGELLATE CRYPTOCHROME BLUE-LIGHT RECEPTOR WITH A POSSIBLE ROLE IN CIRCADIAN CONTROL OF THE CELL CYCLE,JOURNAL OF PHYCOLOGY, Issue 3 2007Stephanie A. Brunelle Karenia brevis (C. C. Davis) G. Hansen et Moestrup is a dinoflagellate responsible for red tides in the Gulf of Mexico. The signaling pathways regulating its cell cycle are of interest because they are the key to the formation of toxic blooms that cause mass marine animal die-offs and human illness. Karenia brevis displays phased cell division, in which cells enter S phase at precise times relative to the onset of light. Here, we demonstrate that a circadian rhythm underlies this behavior and that light quality affects the rate of cell-cycle progression: in blue light, K. brevis entered the S phase early relative to its behavior in white light of similar intensity, whereas in red light, K. brevis was not affected. A data base of 25,000 K. brevis expressed sequence tags (ESTs) revealed several sequences with similarity to cryptochrome blue-light receptors, but none related to known red-light receptors. We characterized the K. brevis cryptochrome (Kb CRY) and modeled its three-dimensional protein structure. Phylogenetic analysis of the photolyase/CRY gene family showed that Kb CRY is a member of the cryptochrome DASH (CRY DASH) clade. Western blotting with an antibody designed to bind a conserved peptide within Kb CRY identified a single band at ,55 kDa. Immunolocalization showed that Kb CRY, like CRY DASH in Arabidopsis, is localized to the chloroplast. This is the first blue-light receptor to be characterized in a dinoflagellate. As the Kb CRY appears to be the only blue-light receptor expressed, it is a likely candidate for circadian entrainment of the cell cycle. [source] | ||||||||||