RESUMEN
We have designed and implemented the first worldwide You Tube channel with 22 videos covering common questions asked in familial cancer susceptibility clinics. We discuss the use of the videos including demographics of registered You Tube users, and what lessons have been learnt about how the general public uses medical information online. The most popular video on inheritance patterns has been watched on average 84 times per month. The mostly highly viewed videos include inheritance patterns, breast cancer screening and hereditary non-polyposis colorectal cancer. Registered viewers were more commonly male and the average age of the registered user was 45-54 years; similar to that seen in Genetics Clinics suggesting that age may not be a major barrier to access to this type of information for patients. The videos have been viewed in more than 140 countries confirming that there is clearly an audience for this type of information. Patient feedback questionnaires indicate that these videos provide a useful aide memoir for the clinic appointment, and most people would recommend them to others. In summary, You Tube videos are easy and cost effective to make. They have the ability to disseminate genetics education to a worldwide audience and may be a useful adjunct to clinical appointments.
Asunto(s)
Internet , Neoplasias/genética , Neoplasias de la Mama/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Salud de la Familia , Retroalimentación , Femenino , Predisposición Genética a la Enfermedad , Humanos , Difusión de la Información , Internet/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Encuestas y Cuestionarios , Grabación en VideoRESUMEN
Dark-grown transgenic Arabidopsis seedlings expressing the C-terminal domains (CCT) of the cryptochrome (CRY) blue light photoreceptors exhibit features that are normally associated only with light-grown seedlings, indicating that the signaling mechanism of Arabidopsis CRY is mediated through CCT. The phenotypic properties mediated by CCT are remarkably similar to those of the constitutive photomorphogenic1 (cop1) mutants. Here we show that Arabidopsis cryptochrome 1 (CRY1) and its C-terminal domain (CCT1) interacted strongly with the COP1 protein. Coimmunoprecipitation studies showed that CRY1 was bound to COP1 in extracts from both dark- and light-grown Arabidopsis. An interaction also was observed between the C-terminal domain of Arabidopsis phytochrome B and COP1, suggesting that phytochrome signaling also proceeds, at least in part, through direct interaction with COP1. These findings give new insight into the initial step in light signaling in Arabidopsis, providing a molecular link between the blue light receptor, CRY1, and COP1, a negative regulator of photomorphogenesis.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis/metabolismo , Proteínas Arqueales , Proteínas de Drosophila , Proteínas del Ojo , Células Fotorreceptoras de Invertebrados , Proteínas de Plantas/metabolismo , Transducción de Señal , Factores de Transcripción , Ubiquitina-Proteína Ligasas , Animales , Arabidopsis/genética , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Criptocromos , Flavoproteínas/genética , Flavoproteínas/metabolismo , Regulación Fúngica de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Humanos , Luz , Modelos Biológicos , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Mutagénesis , Células Fotorreceptoras , Fitocromo/genética , Fitocromo/metabolismo , Fitocromo B , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Mutación Puntual , Unión Proteica , Mapeo de Interacción de Proteínas , Receptores Acoplados a Proteínas G , Saccharomyces cerevisiae/genética , Técnicas del Sistema de Dos HíbridosRESUMEN
Lipoic acid is an essential cofactor for a variety of mitochondrial enzymes. We have characterised a gene from Saccharomyces cerevisiae which appears to encode a protein involved in the attachment of lipoic acid groups to the pyruvate dehydrogenase and glycine decarboxylase complexes. The predicted protein product of this gene has significant identity to the lipoyl ligase B of both Escherichia coli and Kluyveromyces lactis. A strain harbouring a null allele of this S. cerevisiae gene is respiratory deficient due to inactive pyruvate dehydrogenase, and is unable to utilise glycine as a sole nitrogen source.
Asunto(s)
Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/enzimología , Ácido Tióctico/metabolismo , Aciltransferasas , Aminoácido Oxidorreductasas/metabolismo , Secuencia de Aminoácidos , Clonación Molecular , Proteínas Fúngicas/química , Eliminación de Gen , Genes Fúngicos , Glicina-Deshidrogenasa (Descarboxilante) , Mitocondrias/enzimología , Mitocondrias/metabolismo , Datos de Secuencia Molecular , Péptido Sintasas/genética , Péptido Sintasas/metabolismo , Complejo Piruvato Deshidrogenasa/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crecimiento & desarrollo , Análisis de Secuencia de ADNRESUMEN
In photosynthetic cells, chloroplasts migrate towards illuminated sites to optimize photosynthesis and move away from excessively illuminated areas to protect the photosynthetic machinery. Although this movement of chloroplasts in response to light has been known for over a century, the photoreceptor mediating this process has not been identified. The Arabidopsis gene NPL1 (ref. 2) is a paralogue of the NPH1 gene, which encodes phototropin, a photoreceptor for phototropic bending. Here we show that NPL1 is required for chloroplast relocation induced by blue light. A loss-of-function npl1 mutant showed no chloroplast avoidance response in strong blue light, whereas the accumulation of chloroplasts in weak light was normal. These results indicate that NPL1 may function as a photoreceptor mediating chloroplast relocation.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis/fisiología , Cloroplastos/fisiología , Proteínas de Drosophila , Proteínas del Ojo , Luz , Células Fotorreceptoras de Invertebrados , Proteínas de Plantas/genética , Proteínas de Plantas/fisiología , Arabidopsis/genética , Criptocromos , Flavoproteínas/genética , Flavoproteínas/fisiología , Expresión Génica , Genes de Plantas , Movimiento , Mutación , Fosfoproteínas/genética , Fosfoproteínas/fisiología , Hojas de la Planta/fisiología , Proteínas Serina-Treonina Quinasas , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores Acoplados a Proteínas GRESUMEN
Most organisms, from cyanobacteria to mammals, use circadian clocks to coordinate their activities with the natural 24-h light/dark cycle. The clock proteins of Drosophila and mammals exhibit striking homology but do not show similarity with clock proteins found so far from either cyanobacteria or Neurospora. Each of these organisms uses a transcriptionally regulated negative feedback loop in which the messenger RNA levels of the clock components cycle over a 24-h period. Proteins containing PAS domains are invariably found in at least one component of the characterized eukaryotic clocks. Here we describe ADAGIO1 (ADO1), a gene of Arabidopsis thaliana that encodes a protein containing a PAS domain. We found that a loss-of-function ado1 mutant is altered in both gene expression and cotyledon movement in circadian rhythmicity. Under constant white or blue light, the ado1 mutant exhibits a longer period than that of wild-type Arabidopsis seedlings, whereas under red light cotyledon movement and stem elongation are arrhythmic. Both yeast two-hybrid and in vitro binding studies show that there is a physical interaction between ADO1 and the photoreceptors CRY1 and phyB. We propose that ADO1 is an important component of the Arabidopsis circadian system.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis/fisiología , Relojes Biológicos , Ritmo Circadiano , Proteínas de Drosophila , Proteínas del Ojo , Flavoproteínas/metabolismo , Células Fotorreceptoras de Invertebrados , Células Fotorreceptoras , Fitocromo/metabolismo , Proteínas de Plantas/metabolismo , Factores de Transcripción , Animales , Arabidopsis/genética , Northern Blotting , Cotiledón/metabolismo , Criptocromos , Genes de Plantas , Luz , Mutación , Fitocromo B , Proteínas de Plantas/genética , Reacción en Cadena de la Polimerasa , ARN Mensajero/metabolismo , ARN de Planta/metabolismo , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Receptores Acoplados a Proteínas GRESUMEN
Cryptochrome blue light photoreceptors share sequence similarity to photolyases, flavoproteins that mediate light-dependent DNA repair. However, cryptochromes lack photolyase activity and are characterized by distinguishing C-terminal domains. Here we show that the signaling mechanism of Arabidopsis cryptochrome is mediated through the C terminus. On fusion with beta-glucuronidase (GUS), both the Arabidopsis CRY1 C-terminal domain (CCT1) and the CRY2 C-terminal domain (CCT2) mediate a constitutive light response. This constitutive photomorphogenic (COP) phenotype was not observed for mutants of cct1 corresponding to previously described cry1 alleles. We propose that the C-terminal domain of Arabidopsis cryptochrome is maintained in an inactive state in the dark. Irradiation with blue light relieves this repression, presumably through an intra- or intermolecular redox reaction mediated through the flavin bound to the N-terminal photolyase-like domain.
Asunto(s)
Arabidopsis/fisiología , Proteínas de Drosophila , Proteínas del Ojo , Flavoproteínas/química , Flavoproteínas/fisiología , Luz , Células Fotorreceptoras de Invertebrados , Células Fotorreceptoras/fisiología , Alelos , Animales , Antocianinas/biosíntesis , Arabidopsis/metabolismo , Proteínas de Arabidopsis , Núcleo Celular/metabolismo , Criptocromos , Reparación del ADN , Desoxirribodipirimidina Fotoliasa/química , Drosophila , Flavoproteínas/genética , Glucuronidasa/metabolismo , Humanos , Immunoblotting , Modelos Biológicos , Mutagénesis , Oxidación-Reducción , Fenotipo , Plantas Modificadas Genéticamente , Plastidios/fisiología , Mutación Puntual , Estructura Terciaria de Proteína , Receptores Acoplados a Proteínas G , Proteínas Recombinantes de Fusión/metabolismo , Transducción de Señal , TransgenesRESUMEN
Lig1 was found in a differential-display screen for early genes expressed during phytochrome-controlled sporulation of Physarum polycephalum plasmodia. A stretch of 218 amino acids of the predicted sequence of Lig1 shares 32% sequence identity to that of the Schizosaccharomyces pombe cell-cycle and DNA-damage checkpoint gene hus1. In addition Lig1 is homologous to proteins of unknown function in Homo sapiens (35% identity) and Mus musculus (31% identity). Induction of lig1 expression was found to be controlled downstream from the point of integration of the phytochrome-activated pathway and the pathway sensing the metabolic state, but upstream of the developmental switch. The lig1 expression level in individual plasmodia correlated positively with the probability to sporulate. Sensory control of the lig1 expression level and its association with the developmental switch suggests a possible mechanism for the coordination of differentiation and the control of cell-cycle progression during the sporulation of P. polycephalum.
Asunto(s)
Proteínas de Ciclo Celular/genética , Regulación del Desarrollo de la Expresión Génica , Physarum polycephalum/genética , Fitocromo/metabolismo , Proteínas Protozoarias , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Ciclo Celular , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Diferenciación Celular , Genes Protozoarios/genética , Genes Protozoarios/fisiología , Luz , Datos de Secuencia Molecular , Physarum polycephalum/citología , Physarum polycephalum/crecimiento & desarrollo , Physarum polycephalum/metabolismo , ARN Mensajero/análisis , ARN Mensajero/genética , ARN Protozoario/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Schizosaccharomyces/genética , Proteínas de Schizosaccharomyces pombe , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Esporas/genética , Activación TranscripcionalRESUMEN
Cryptochromes are blue, ultraviolet-A photoreceptors. They were first characterized for Arabidopsis and are also found in ferns and algae; they appear to be ubiquitous in the plant kingdom. They are flavoproteins similar in sequence to photolyases, their presumptive evolutionary ancestors. Cryptochromes mediate a variety of light responses, including entrainment of circadian rhythms in Arabidopsis, Drosophila, and mammals. Sequence comparison indicates that the plant and animal cryptochrome families have distinct evolutionary histories, with the plant cryptochromes being of ancient evolutionary origin and the animal cryptochromes having evolved relatively recently. This process of repeated evolution may have coincided with the origin in animals of a modified circadian clock based on the PERIOD, TIMELESS, CLOCK, and CYCLE proteins.
Asunto(s)
Desoxirribodipirimidina Fotoliasa/metabolismo , Proteínas de Drosophila , Proteínas del Ojo , Flavoproteínas/fisiología , Células Fotorreceptoras de Invertebrados , Células Fotorreceptoras/fisiología , Transducción de Señal , Animales , Núcleo Celular/metabolismo , Ritmo Circadiano , Criptocromos , Desoxirribodipirimidina Fotoliasa/química , Evolución Molecular , Flavoproteínas/química , Humanos , Luz , Células Fotorreceptoras/química , Proteínas del Complejo del Centro de Reacción Fotosintética/metabolismo , Plantas/metabolismo , Receptores Acoplados a Proteínas GRESUMEN
Mobilizable shuttle plasmids containing the origin-of-transfer (oriT) region of plasmids F (IncFI), ColIb-P9 (IncI1), and RP4/RP1 (IncPalpha) were constructed to test the ability of the cognate conjugation system to mediate gene transfer from Escherichia coli to Saccharomyces cerevisiae. Only the Palpha system caused detectable mobilization to yeast, giving peak values of 5 x 10(-5) transconjugants per recipient cell in 30 min. Transfer of the shuttle plasmid required carriage of oriT in cis and the provision in trans of the Palpha Tra1 core and Tra2 core regions. Genes outside the Tra1 core did not increase the mobilization efficiency. All 10 Tra2 core genes (trbB, -C, -D, -E, -F, -G, -H, -I, -J, and -L) required for plasmid transfer to E. coli K-12 were needed for transfer to yeast. To assess whether the mating-pair formation (Mpf) system or DNA-processing apparatus of the Palpha conjugation system is critical in transkingdom transfer, an assay using an IncQ-based shuttle plasmid specifying its own DNA-processing system was devised. RP1 but not ColIb mobilized the construct to yeast, indicating that the Mpf complex determined by the Tra2 core genes plus traF is primarily responsible for the remarkable fertility of the Palpha system in mediating gene transfer from bacteria to eukaryotes.
Asunto(s)
Conjugación Genética , Escherichia coli/genética , Plásmidos , Saccharomyces cerevisiae/genéticaRESUMEN
Plants have at least two major photosensory receptors: phytochrome (absorbing primarily red/far-red light) and cryptochrome (absorbing blue/UV-A light); considerable physiological and genetic evidence suggests some form of communication or functional dependence between the receptors. Here, we demonstrate in vitro, using purified recombinant photoreceptors, that Arabidopsis CRY1 and CRY2 (cryptochrome) are substrates for phosphorylation by a phytochrome A-associated kinase activity. Several mutations within the CRY1 C terminus lead to reduced phosphorylation by phytochrome preparations in vitro. Yeast two-hybrid interaction studies using expressed C-terminal fragments of CRY1 and phytochrome A from Arabidopsis confirm a direct physical interaction between both photoreceptors. In vivo labeling studies and specific mutant alleles of CRY1, which interfere with the function of phytochrome, suggest the possible relevance of these findings in vivo.
Asunto(s)
Arabidopsis/química , Proteínas de Drosophila , Proteínas del Ojo , Flavoproteínas/metabolismo , Células Fotorreceptoras de Invertebrados , Células Fotorreceptoras/metabolismo , Fitocromo/metabolismo , Proteínas de Plantas/metabolismo , Alelos , Arabidopsis/genética , Arabidopsis/fisiología , Proteínas de Arabidopsis , Criptocromos , Flavoproteínas/química , Flavoproteínas/genética , Mutación/genética , Mutación/fisiología , Fosfatos , Fosforilación/efectos de la radiación , Fosfotransferasas/metabolismo , Células Fotorreceptoras/química , Fitocromo/química , Fitocromo/fisiología , Fitocromo A , Proteínas de Plantas/química , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Unión Proteica , Receptores Acoplados a Proteínas G , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Saccharomyces cerevisiae/genéticaRESUMEN
Phototropism-bending towards the light-is one of the best known plant tropic responses. Despite being reported by Darwin and others over a century ago to be specifically under the control of blue light, the photoreceptors mediating phototropism have remained unknown. We have characterized a blue-light photoreceptor from Arabidopsis, named CRY1 for cryptochrome 1; this photoreceptor is a flavoprotein that mediates numerous blue-light-dependent responses. In Arabidopsis, HY4 (the gene encoding CRY1) is a member of a small gene family that also encodes a related photoreceptor, CRY2, which shares considerable functional overlap with CRY1. Here we report that mutant plants lacking both the CRY1 and the CRY2 blue-light photoreceptors are deficient in the phototropic response. Transgenic Arabidopsis plants overexpressing CRY1 or CRY2 show enhanced phototropic curvature. We conclude that cryptochrome is one of the photoreceptors mediating phototropism in plants.
Asunto(s)
Arabidopsis/fisiología , Proteínas de Drosophila , Proteínas del Ojo , Flavoproteínas/fisiología , Células Fotorreceptoras de Invertebrados , Células Fotorreceptoras/fisiología , Fototropismo , Proteínas de Plantas/fisiología , Antocianinas/metabolismo , Proteínas de Arabidopsis , Criptocromos , Flavoproteínas/genética , Mutación , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Receptores Acoplados a Proteínas GRESUMEN
Cryptochrome is a group of flavin-type blue light receptors that regulate plant growth and development. The function of Arabidopsis cryptochrome 2 in the early photomorphogenesis of seedlings was studied by using transgenic plants overexpressing CRY2 protein, and cry2 mutant plants accumulating no CRY2 protein. It is found that cryptochrome 2 mediates blue light-dependent inhibition of hypocotyl elongation and stimulation of cotyledon opening under low intensities of blue light. In contrast to CRY1, the expression of CRY2 is rapidly down-regulated by blue light in a light-intensity dependent manner, which provides a molecular mechanism to explain at least in part that cryptochrome 2 functions primarily under low light during the early development of seedlings.
Asunto(s)
Arabidopsis/fisiología , Proteínas de Drosophila , Proteínas del Ojo , Flavoproteínas/fisiología , Células Fotorreceptoras de Invertebrados , Proteínas de Plantas/fisiología , Secuencia de Aminoácidos , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis , Criptocromos , Desoxirribodipirimidina Fotoliasa/química , Escherichia coli/enzimología , Flavoproteínas/biosíntesis , Flavoproteínas/química , Hipocótilo , Luz , Iluminación , Datos de Secuencia Molecular , Proteínas de Plantas/biosíntesis , Proteínas de Plantas/química , Receptores Acoplados a Proteínas G , Alineación de Secuencia , Homología de Secuencia de AminoácidoRESUMEN
A blue light (cryptochrome) photoreceptor from Arabidopsis, cry1, has been identified recently and shown to mediate a number of blue light-dependent phenotypes. Similar to phytochrome, the cryptochrome photoreceptors are encoded by a gene family of homologous members with considerable amino acid sequence similarity within the N-terminal chromophore binding domain. The two members of the Arabidopsis cryptochrome gene family (CRY1 and CRY2) overlap in function, but their proteins differ in stability: cry2 is rapidly degraded under light fluences (green, blue, and UV) that activate the photoreceptor, but cry1 is not. Here, we demonstrate by overexpression in transgenic plants of cry1 and cry2 fusion constructs that their domains are functionally interchangeable. Hybrid receptor proteins mediate functions similar to cry1 and include inhibition of hypocotyl elongation and blue light-dependent anthocyanin accumulation; differences in activity appear to be correlated with differing protein stability. Because cry2 accumulates to high levels under low-light intensities, it may have greater significance in wild-type plants under conditions when light is limited.
Asunto(s)
Arabidopsis/fisiología , Proteínas de Drosophila , Proteínas del Ojo , Flavoproteínas/fisiología , Células Fotorreceptoras de Invertebrados , Proteínas de Plantas/fisiología , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Proteínas de Arabidopsis , Criptocromos , Cicloheximida/farmacología , Flavoproteínas/biosíntesis , Flavoproteínas/genética , Fenotipo , Células Fotorreceptoras , Proteínas de Plantas/biosíntesis , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Receptores Acoplados a Proteínas G , Proteínas Recombinantes de Fusión , Alineación de SecuenciaRESUMEN
The G-box is an important regulatory element found in the promoters of many different genes. Four members of an Arabidopsis gene family encoding basic leucine zipper proteins (GBFs) which bind the G-box have previously been cloned. To study GBFs, a polyclonal antibody was raised against GBF1 expressed in bacteria. This antibody also recognized GBF2 and GBF3. Immunoblot analysis of nuclear and cytoplasmic fractions from Arabidopsis and soybean (SB-M) cell cultures indicated that over 90% of proteins detected with anti-GBF1 were cytoplasmic. Electrophoretic mobility shift assays indicated that over 90% of G-box binding activity was cytoplasmic. DNA affinity chromatography demonstrated that each protein detected with anti-GBF1 specifically bound the G-box. To study individual GBFs, DNA constructs fusing GBF1, GBF2 and GBF4 to GUS were made and assayed by transient expression in SB-M protoplasts. Of GUS:GBF1 proteins, 50-62% were localized in the cytoplasm under all conditions tested, while 97% of GUS:GBF4 was localized in the nucleus. By contrast, whereas about 50% of GUS:GBF2 was found in the cytoplasm of dark-grown cells, over 80% of this protein was found in the nucleus in cells cultured under blue light. Deletion analysis of GBF1 identified a region between amino acids 112 and 164 apparently required for cytoplasmic retention. These results suggest the intriguing possibility that limitation of nuclear access may be an important control on GBF activity. In particular, GBF2 is apparently specifically imported into the nucleus in response to light.
Asunto(s)
Compartimento Celular/efectos de la radiación , Proteínas de Unión al ADN/metabolismo , Leucina Zippers , Proteínas de Plantas/metabolismo , Factores de Transcripción/metabolismo , Especificidad de Anticuerpos , Arabidopsis/citología , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico , Transporte Biológico/efectos de la radiación , Núcleo Celular/metabolismo , Células Cultivadas , Citoplasma/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/inmunología , Oscuridad , Factores de Unión a la G-Box , Genes Reporteros , Glucuronidasa/genética , Proteínas Fluorescentes Verdes , Luz , Proteínas Luminiscentes/genética , Proteínas de Plantas/genética , Unión Proteica , Proteínas Recombinantes de Fusión/metabolismo , Transducción de Señal , Glycine max/citología , Factores de Transcripción/genética , Factores de Transcripción/inmunologíaRESUMEN
Blue-light responses in higher plants are mediated by specific photoreceptors, which are thought to be flavoproteins; one such flavin-type blue-light receptor, CRY1 (for cryptochrome), which mediates inhibition of hypocotyl elongation and anthocyanin biosynthesis, has recently been characterized. Prompted by classical photobiological studies suggesting possible co-action of the red/far-red absorbing photoreceptor phytochrome with blue-light photoreceptors in certain plant species, the role of phytochrome in CRY1 action in Arabidopsis was investigated. The activity of the CRY1 photoreceptor can be substantially altered by manipulating the levels of active phytochrome (Pfr) with red or far-red light pulses subsequent to blue-light treatments. Furthermore, analysis of severely phytochrome-deficient mutants showed that CRY1-mediated blue-light responses were considerably reduced, even though Western blots confirmed that levels of CRY1 photoreceptor are unaffected in these phytochrome-deficient mutant backgrounds. It was concluded that CRY1-mediated inhibition of hypocotyl elongation and anthocyanin production requires active phytochrome for full expression, and that this requirement can be supplied by low levels of either phyA or phyB.
Asunto(s)
Arabidopsis/fisiología , Proteínas de Drosophila , Proteínas del Ojo , Flavoproteínas/fisiología , Luz , Células Fotorreceptoras de Invertebrados , Células Fotorreceptoras , Fitocromo/fisiología , Proteínas de Plantas/fisiología , Factores de Transcripción , Antocianinas/biosíntesis , Arabidopsis/genética , Proteínas de Arabidopsis , Criptocromos , Flavoproteínas/biosíntesis , Flavoproteínas/genética , Hipocótilo , Cinética , Fitocromo A , Fitocromo B , Proteínas de Plantas/biosíntesis , Proteínas de Plantas/genética , Receptores Acoplados a Proteínas GRESUMEN
The important issue of photoreactivation DNA repair in plants has become even more interesting in recent years because a family of genes that are highly homologous to photoreactivating DNA repair enzymes but that function as blue light photoreceptors has been isolated. Here, we report the isolation of a novel photolyase-like sequence from Arabidopsis designated PHR1 (for photoreactivating enzyme). It shares little sequence similarity with either type I photolyases or the cryptochrome family of blue light photoreceptors. Instead, the PHR1 gene encodes an amino acid sequence with significant homology to the recently characterized type II photolyases identified in a number of prokaryotic and animal systems. PHR1 is a single-copy gene and is not expressed in dark-grown etiolated seedlings: the message is light inducible, which is similar to the expression profile for photoreactivation activity in plants. The PHR1 protein complements a photolyase-deficient mutant of Escherichia coli and thus confers photoreactivation activity. In addition, an Arabidopsis mutant that is entirely lacking in photolyase activity has been found to contain a lesion within this Arabidopsis type II photolyase sequence. We conclude that PHR1 represents a genuine plant photolyase gene and that the plant genes with homology to type I photolyases (the cryptochrome family of blue light photoreceptors) do not contribute to photoreactivation repair, at least in the case of Arabidopsis.