RESUMEN
The TRANSPARENT TESTA GLABRA1 (TTG1) locus regulates several developmental and biochemical pathways in Arabidopsis, including the formation of hairs on leaves, stems, and roots, and the production of seed mucilage and anthocyanin pigments. The TTG1 locus has been isolated by positional cloning, and its identity was confirmed by complementation of a ttg1 mutant. The locus encodes a protein of 341 amino acid residues with four WD40 repeats. The protein is similar to AN11, a regulator of anthocyanin biosynthesis in petunia, and more distantly related to those of the beta subunits of heterotrimeric G proteins, which suggests a role for TTG1 in signal transduction to downstream transcription factors. The 1.5-kb TTG1 transcript is present in all major organs of Arabidopsis. Sequence analysis of six mutant alleles has identified base changes producing truncations or single amino acid changes in the TTG1 protein.
Asunto(s)
Antocianinas/biosíntesis , Proteínas de Arabidopsis , Arabidopsis/genética , Proteínas de Plantas/genética , Alelos , Secuencia de Aminoácidos , Arabidopsis/metabolismo , Secuencia de Bases , ADN de Plantas , Prueba de Complementación Genética , Datos de Secuencia Molecular , Mutación , Proteínas de Plantas/fisiología , Conformación Proteica , Homología de Secuencia de AminoácidoRESUMEN
The ETR1 receptor from Arabidopsis binds the gaseous hormone ethylene. A copper ion associated with the ethylene-binding domain is required for high-affinity ethylene-binding activity. A missense mutation in the domain that renders the plant insensitive to ethylene eliminates both ethylene binding and the interaction of copper with the receptor. A sequence from the genome of the cyanobacterium Synechocystis sp. strain 6803 that shows homology to the ethylene-binding domain of ETR1 encodes a functional ethylene-binding protein. On the basis of sequence conservation between the Arabidopsis and the cyanobacterial ethylene-binding domains and on in vitro mutagenesis of ETR1, a structural model for this copper-based ethylene sensor domain is presented.
Asunto(s)
Arabidopsis/metabolismo , Cobre/metabolismo , Etilenos/metabolismo , Proteínas de Plantas/metabolismo , Receptores de Superficie Celular/metabolismo , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Arabidopsis/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Sitios de Unión , Secuencia Conservada , Cobre/análisis , Sulfato de Cobre/farmacología , Cianobacterias/genética , Cianobacterias/metabolismo , Dimerización , Modelos Moleculares , Mutagénesis , Sistemas de Lectura Abierta , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/aislamiento & purificación , Receptores de Superficie Celular/química , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/aislamiento & purificación , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Saccharomyces cerevisiae , Plata/metabolismo , Plata/farmacologíaRESUMEN
The gaseous hormone ethylene regulates many aspects of plant growth and development. Ethylene is perceived by a family of high-affinity receptors typified by the ETR1 protein from Arabidopsis. The ETR1 gene codes for a protein which contains a hydrophobic N-terminal domain that binds ethylene and a C-terminal domain that is related in sequence to histidine kinase-response regulator two-component signal transducers found in bacteria. A structural model for the ethylene-binding domain is presented in which a Cu(I) ion is coordinated within membrane-spanning alpha-helices of the hydrophobic domain. It is proposed that binding of ethylene to the transition metal would induce a conformational change in the sensor domain that would be propagated to the cytoplasmic transmitter domain of the protein. A total of four additional genes that are related in sequence to ETR1 have been identified in Arabidopsis. Specific missense mutations in any one of the five genes leads to ethylene insensitivity in planta. Models for signal transduction that can account for the genetic dominance of these mutations are discussed.
Asunto(s)
Arabidopsis/metabolismo , Proteínas de Plantas/química , Receptores de Superficie Celular/química , Arabidopsis/genética , Etilenos/metabolismo , Genes de Plantas , Modelos Biológicos , Modelos Moleculares , Mutación , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Conformación Proteica , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Transducción de SeñalRESUMEN
Appendage formation is organized by signals from discrete sources that presumably act upon downstream genes to control growth and patterning. The Drosophila vestigial gene is selectively required for wing-cell proliferation, and is sufficient to induce outgrowths of wing tissue from eyes, legs and antennae. Different signals activate separate enhancers to control vestigial expression: first, in the dorsal/ventral organizer through the Notch pathway, and subsequently, in the developing wing blade by decapentaplegic and a signal from the dorsal/ventral organizer. Signal integration must be a general feature of genes like vestigial, that regulate growth or patterning along more than one axis.
Asunto(s)
Proteínas de Drosophila , Drosophila/genética , Regulación del Desarrollo de la Expresión Génica , Proteínas Nucleares/genética , Transducción de Señal , Alas de Animales/embriología , Animales , Secuencia de Bases , ADN , Huella de ADN , Drosophila/embriología , Elementos de Facilitación Genéticos , Hormonas de Insectos/fisiología , Datos de Secuencia Molecular , Proteínas Nucleares/fisiología , Proteínas Represoras/fisiologíaRESUMEN
A genomic clone containing the gl1-2 allele has been isolated and sequenced. The predicted amino acid sequence of the gl1-2 protein is identical to that of the GL1-Col allele up to position 201. At this point in the coding region of gl1-2 there is a deletion relative to the wild-type sequence that results in an in-frame stop codon at position 202. This deletion removes 27 amino acid residues, including a highly negatively charged region, from the predicted gl1-2 polypeptide. The loss of this negatively charged carboxy-terminal region from the gl1-2 product is most likely the cause of the partial loss of gene activity which results in a reduction in leaf trichome initiation.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis/genética , Proteínas de Unión al ADN , Genes de Plantas , Proteínas de Plantas/genética , Alelos , Secuencia de Aminoácidos , Arabidopsis/ultraestructura , Secuencia de Bases , Clonación Molecular , ADN , Exones , Datos de Secuencia Molecular , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido NucleicoRESUMEN
Self-incompatibility in Brassica oleracea is controlled by the highly polymorphic S locus. Isolation and subsequent characterization of the S-locus-glycoprotein (SLG) gene, which encodes the S-locus-specific glycoprotein (SLSG), has revealed the presence of a self-incompatibility multigene family. One of these S-locus-related genes, SLR1, has been shown to be expressed. In this study we present the isolation and preliminary characterization of a second expressed S-locus-related sequence, SLR2. Through restriction fragment length polymorphism (RFLP) linkage analysis we demonstrate that the SLR1 and SLR2 loci reside approximately 18.5 map units apart in one linkage group that segregates independently of the S-locus. The identification of a second SLR gene expressed in stigmas suggests that loci unlinked to the S-locus may play a role in the self-incompatibility response, or in pollination in general.