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1.
Plant J ; 37(4): 566-77, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14756763

RESUMO

Flower development in angiosperms is regulated by the family of MADS-box transcription factors. MADS-box genes have also been reported from gymnosperms, another major group of seed plants. AGAMOUS (AG) is the class C MADS-box floral organ identity gene controlling the stamen and carpel development in Arabidopsis. We report the characterization of an ortholog of the AG gene, named Cycas AGAMOUS (CyAG), from the primitive gymnosperm Cycas edentata. The expression pattern of CyAG in Cycas parallels that of AG in Arabidopsis. Additionally, the gene structure, including the number and location of the introns, is conserved in CyAG and other AG orthologs known. Most importantly, functional analysis shows that CyAG driven by the AG promoter can rescue the loss-of-function ag mutant of Arabidopsis. However, the ectopic expression of CyAG in ag mutant Arabidopsis cannot produce the carpeloid and stamenoid organs in the first and second whorls, although the stamen and carpel are rescued in the third and fourth whorls of the transformants. These observations show that the molecular mechanism of class C function controlling reproductive organ identity (stamen and carpel of angiosperms or microsporophyll and megasporophyll of gymnosperms) arose before the divergence of angiosperms and gymnosperms, and has been conserved during 300 million years of evolution thereafter.


Assuntos
Cycadopsida/crescimento & desenvolvimento , Evolução Molecular , Flores/crescimento & desenvolvimento , Proteínas de Domínio MADS/genética , Magnoliopsida/crescimento & desenvolvimento , Proteínas de Plantas/genética , Sequência de Aminoácidos , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Clonagem Molecular , Cycadopsida/química , Cycadopsida/genética , Cycadopsida/metabolismo , Cycas/genética , Cycas/crescimento & desenvolvimento , Cycas/metabolismo , DNA de Plantas/química , DNA de Plantas/genética , Flores/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/metabolismo , Magnoliopsida/genética , Magnoliopsida/metabolismo , Dados de Sequência Molecular , Mutação , Filogenia , Proteínas de Plantas/metabolismo , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos
2.
Gene ; 312: 103-9, 2003 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-12909345

RESUMO

We isolated a 918 bp long full-length rice HMGB1 cDNA, which has an open reading frame of 471 bp encoding 157 amino acids, with a central domain of high sequence similarity to the HMG-box domain of other plant HMGB1 proteins. RNA gel blot analysis indicated that rice HMGB1 gene is constitutively expressed in various tissues and organs. Southern hybridization and sequence analyses suggested that a single copy of the HMGB1 gene composed of seven exons and six introns exists in rice. We have also cloned a 1755 bp long 5' flanking region of the rice HMGB1 gene, which can be regarded as its promoter. 5' deletion analysis of this promoter indicated that positive cis-elements residing between -1400 and -1115 are important to enhance quantitative expression, whereas negative cis-elements between -1755 and -1400 and between -1115 and -351 inhibit expression.


Assuntos
Proteína HMGB1/genética , Oryza/genética , Região 5'-Flanqueadora/genética , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , DNA Complementar/química , DNA Complementar/genética , DNA de Plantas/química , DNA de Plantas/genética , Éxons , Regulação da Expressão Gênica de Plantas , Glucuronidase/genética , Glucuronidase/metabolismo , Íntrons , Dados de Sequência Molecular , Proteínas de Plantas/genética , Regiões Promotoras Genéticas/genética , RNA de Plantas/genética , RNA de Plantas/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos
3.
Biochemistry ; 42(21): 6596-607, 2003 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-12767244

RESUMO

Wheat HMGa protein is a typical member of the plant HMGA family. It has four AT hooks and a histone H1-like region. A panel of deletion mutants of HMGa was generated to study the role of different regions of HMGa in its binding to 4H (a synthetic DNA that mimics the in vivo structure of intermediates of homologous recombination and DNA repair) and linear DNAs. Although the histone H1-like region of HMGa does not bind to 4H or linear DNAs, it does enhance the binding. Mutants with any two adjacent AT hooks show specific binding to both 4H and linear P268 (and P31) with different binding affinities, which is partly due to the flanking regions between AT hooks. Conformational studies indicate that the alpha-helical content of HMGa increases significantly when it binds to 4H compared to that after binding to P31, linear DNA. In contrast, linear DNA, but not 4H, undergoes substantial conformational change when it binds to HMGa, indicating that linear DNA is relatively more flexible than 4H. A more significant difference in the affinities of binding of the mutants of HMGa to 4H was observed compared to their affinities of binding to linear DNA, P31. These differences could be due to the rigidity of the DNA and the characters of the AT hook regions in the mutants.


Assuntos
DNA/química , Proteínas de Grupo de Alta Mobilidade/química , Proteínas de Plantas , Triticum/metabolismo , Sequência de Aminoácidos , Dicroísmo Circular , DNA/metabolismo , Deleção de Genes , Histonas/química , Cinética , Dados de Sequência Molecular , Mutação , Plasmídeos/metabolismo , Ligação Proteica , Conformação Proteica , Estrutura Terciária de Proteína , Relação Estrutura-Atividade , Ressonância de Plasmônio de Superfície , Fatores de Tempo
4.
Arch Biochem Biophys ; 411(1): 105-11, 2003 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-12590928

RESUMO

We analyzed the DNA-binding and DNA-bending properties of recombinant HMGB1 proteins based on a rice HMGB1 cDNA. Electrophoretic mobility shift assay demonstrated that rice HMGB1 can bind synthetic four-way junction (4H) DNA and DNA minicircles efficiently but the binding to 4H can be completed out by HMGA and histone H1. Conformational changes were detected by circular dichroism analysis with 4H DNA bound to various concentrations of HMGB1 or its truncated forms. T4 ligase-mediated circularization assays with short DNA fragments of 123 bp showed that the protein is capable of increasing DNA flexibility. The 123-bp DNA formed closed circular monomers efficiently in its presence, similar to that in an earlier study on maize HMG. Additionally, our results show for the first time that the basic N-terminal domain enhances the affinity of the plant HMGB1 protein for 4H DNA, while the acidic C-terminal domain has the converse effects.


Assuntos
DNA/química , Proteína HMGB1/química , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos/química , Oryza/química , Sequência de Bases , Dicroísmo Circular , DNA/efeitos dos fármacos , DNA Complementar/química , Proteína HMGB1/farmacologia , Proteínas de Plantas/química , Proteínas de Plantas/farmacologia , Reação em Cadeia da Polimerase
5.
Arch Biochem Biophys ; 409(2): 357-66, 2003 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-12504903

RESUMO

Plant high-mobility-group (HMG) chromosomal proteins are the most abundant and ubiquitous nonhistone proteins found in the nuclei of higher eukaryotes. There are only two families of HMG proteins, namely, HMGA and HMGB in plants. The cDNA encoding wheat HMGa protein was isolated and characterized. Wheat HMGA cDNA encodes a protein of 189 amino acid residues. At its N terminus, there is a histone H1-like structure, which is a common feature of plant HMGA proteins, followed by four AT-hook motifs. Polymerase chain reaction results show that the gene contains a single intron of 134 bp. All four AT-hook motifs are encoded by the second exon. Northern blot results show that the expression of HMGA gene is much higher in organs undergoing active cell proliferation. Gel retardation analysis show that wheat HMGa, b, c and histone H1 bind to four-way-junction DNA with high binding affinity, but affinity is dramatically reduced with increasing Mg(2+) and Na(+) ion concentration. Competition binding studies show that proteins share overlapping binding sites on four-way-junction DNA. HMGd does not bind to four-way-junction DNA.


Assuntos
DNA de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas HMGA/química , Proteínas HMGA/genética , Proteínas de Grupo de Alta Mobilidade/genética , Proteínas Nucleares/genética , Proteínas de Plantas/genética , Triticum/genética , Triticum/metabolismo , Motivos AT-Hook , Sequência de Aminoácidos , Sequência de Bases , Divisão Celular , DNA de Plantas/química , Proteínas de Ligação a DNA/efeitos dos fármacos , Proteínas de Ligação a DNA/metabolismo , Relação Dose-Resposta a Droga , Éxons , Proteínas HMGA/efeitos dos fármacos , Proteínas HMGA/isolamento & purificação , Proteínas HMGA/metabolismo , Proteínas HMGB/efeitos dos fármacos , Proteínas HMGB/metabolismo , Proteínas de Grupo de Alta Mobilidade/isolamento & purificação , Proteínas de Grupo de Alta Mobilidade/metabolismo , Histonas/efeitos dos fármacos , Histonas/metabolismo , Íntrons , Magnésio/farmacologia , Dados de Sequência Molecular , Proteínas Nucleares/isolamento & purificação , Proteínas Nucleares/metabolismo , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/metabolismo , Ligação Proteica/efeitos dos fármacos , Estrutura Terciária de Proteína , Sódio/farmacologia , Espermidina/farmacologia
6.
Mech Dev ; 114(1-2): 149-52, 2002 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12175502

RESUMO

To better understand the molecular mechanisms controlling development of sexual characters in Cycas edentata, we attempted to clone genes expressed differentially in male or female reproductive organs. We report a novel gene, named Fortune-1 (Ft-1), with enhanced expression in male reproductive organs. The 593-base-pair Ft-1 cDNA is predicted to encode a 77-amino-acid protein, and exists as a single copy gene in the C. edentata genome. Ft-1 expression is enhanced in male cones, including the cone axis, microsporophylls and microsporangia, but is reduced in ovules and undetectable in megasporophylls. Ft-1 is also weakly detectable in leaves. In roots and stems of C. edentata, Ft-1 transcripts are undetectable. The secondary structure prediction and homology search of Ft-1 protein show that it has a helix-loop-helix motif, and is without any homologue in the database.


Assuntos
Gleiquênias/genética , Fenômenos Fisiológicos Vegetais , Proteínas de Plantas/biossíntese , Proteínas de Plantas/genética , Sequência de Aminoácidos , Sequência de Bases , Southern Blotting , Clonagem Molecular , DNA Complementar/metabolismo , Hibridização In Situ , Dados de Sequência Molecular , RNA Mensageiro/metabolismo , Homologia de Sequência de Aminoácidos
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