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1.
EMBO J ; 25(18): 4400-11, 2006 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-16957775

RESUMO

Plants use sophisticated strategies to balance responses to oxidative stress. Programmed cell death, including the hypersensitive response (HR) associated with successful pathogen recognition, is one cellular response regulated by reactive oxygen in various cellular contexts. The Arabidopsis basic leucine zipper (bZIP) transcription factor AtbZIP10 shuttles between the nucleus and the cytoplasm and binds consensus G- and C-box DNA sequences. Surprisingly, AtbZIP10 can be retained outside the nucleus by LSD1, a protein that protects Arabidopsis cells from death in the face of oxidative stress signals. We demonstrate that AtbZIP10 is a positive mediator of the uncontrolled cell death observed in lsd1 mutants. AtbZIP10 and LSD1 act antagonistically in both pathogen-induced HR and basal defense responses. LSD1 likely functions as a cellular hub, where its interaction with AtbZIP10 and additional, as yet unidentified, proteins contributes significantly to plant oxidative stress responses.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Proteínas de Ligação a DNA/metabolismo , Fatores de Transcrição/metabolismo , Apoptose , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Fatores de Transcrição de Zíper de Leucina Básica/genética , Citoplasma/metabolismo , Proteínas de Ligação a DNA/genética , Genes de Plantas , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Mutação , Oomicetos/patogenicidade , Estresse Oxidativo , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Plantas Geneticamente Modificadas , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/genética , Técnicas do Sistema de Duplo-Híbrido
2.
Development ; 132(9): 2191-202, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15799999

RESUMO

Neurotrophins (Nt) and their tyrosine kinase Trk receptors play an essential role in the development and maintenance of the complex vertebrate nervous system. Invertebrate genome sequencing projects have suggested that the Nt/Trk system is a vertebrate innovation. We describe the isolation and characterisation of the amphioxus Trk receptor, AmphiTrk. Its ancestral link to vertebrate Trk receptors is supported by phylogenetic analysis and domain characterisation. The genomic structure of AmphiTrk strongly suggests that a ProtoTrk gene emerged by means of exon-shuffling prior to the cephalochordate/vertebrate split. We also examined the physiological response of AmphiTrk to vertebrate neurotrophins, and found that despite 500 million years of divergence, AmphiTrk transduces signals mediated by NGF, BDNF, NT3 and NT4. Markedly, AmphiTrk is able to activate survival and differentiation pathways, but fails to activate the PLCgamma pathway, which is involved in synaptic plasticity in higher vertebrates. AmphiTrk is expressed during amphioxus embryogenesis in sensory neural precursors in the epidermis, which possesses single migratory cells. We propose that the duplication and divergence of the Nt/Trk system, in tandem with recruitment of the PLCgamma pathway, may have provided the genetic basis for a key aspect of vertebrate evolution: the complexity of the nervous system.


Assuntos
Cordados não Vertebrados/metabolismo , Fatores de Crescimento Neural/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Células Receptoras Sensoriais/metabolismo , Transdução de Sinais/fisiologia , Sequência de Aminoácidos , Animais , Southern Blotting , Cordados não Vertebrados/embriologia , Humanos , Dados de Sequência Molecular , Estrutura Terciária de Proteína , Células Receptoras Sensoriais/embriologia , Análise de Sequência de Proteína , Vertebrados/metabolismo
3.
Plant J ; 40(3): 428-38, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15469500

RESUMO

Dynamic networks of protein-protein interactions regulate numerous cellular processes and determine the ability to respond appropriately to environmental stimuli. However, the investigation of protein complex formation in living plant cells by methods such as fluorescence resonance energy transfer has remained experimentally difficult, time consuming and requires sophisticated technical equipment. Here, we report the implementation of a bimolecular fluorescence complementation (BiFC) technique for visualization of protein-protein interactions in plant cells. This approach relies on the formation of a fluorescent complex by two non-fluorescent fragments of the yellow fluorescent protein brought together by association of interacting proteins fused to these fragments (Hu et al., 2002). To enable BiFC analyses in plant cells, we generated different complementary sets of expression vectors, which enable protein interaction studies in transiently or stably transformed cells. These vectors were used to investigate and visualize homodimerization of the basic leucine zipper (bZIP) transcription factor bZIP63 and the zinc finger protein lesion simulating disease 1 (LSD1) from Arabidopsis as well as the dimer formation of the tobacco 14-3-3 protein T14-3c. The interaction analyses of these model proteins established the feasibility of BiFC analyses for efficient visualization of structurally distinct proteins in different cellular compartments. Our investigations revealed a remarkable signal fluorescence intensity of interacting protein complexes as well as a high reproducibility and technical simplicity of the method in different plant systems. Consequently, the BiFC approach should significantly facilitate the visualization of the subcellular sites of protein interactions under conditions that closely reflect the normal physiological environment.


Assuntos
Arabidopsis/metabolismo , Nicotiana/metabolismo , Proteínas de Plantas/metabolismo , Espectrometria de Fluorescência/métodos , Proteínas de Arabidopsis/metabolismo , Proteínas de Bactérias , Fatores de Transcrição de Zíper de Leucina Básica , Citoplasma/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas Luminescentes , Ligação Proteica , Multimerização Proteica , Sensibilidade e Especificidade , Fatores de Transcrição/metabolismo
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