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F Madueño

Publications and source records attributed to F Madueño.

17 recordsLinked to original sources
PubMed2001

Analysis of PEAM4, the pea AP1 functional homologue, supports a model for AP1-like genes controlling both floral meristem and floral organ identity in different plant species.

APETALA1 (AP1) and its homologue SQUAMOSA (SQUA) are key regulatory genes specifying floral meristem identity in the model plants Arabidopsis and Antirrhinum. Despite many similarities in their sequence, expression and functions, only AP1 appears to have the additional role of specifying sepal and petal identity. No true AP1/SQUA-functional homologues from any other plant species have been functionally studied in detail, therefore the question of how the different functions of AP1-like genes are conserved between species has not been addressed. We have isolated and characterized PEAM4, the AP1/SQUA-functional homologue from pea, a plant with a different floral morphology and inflorescence architecture to that of Arabidopsis or Antirrhinum. PEAM4 encodes for a polypeptide 76% identical to AP1, but lacks the C-terminal prenylation motif, common to AP1 and SQUA, that has been suggested to control the activity of AP1. Nevertheless, constitutive expression of PEAM4 caused early flowering in tobacco and Arabidopsis. In Arabidopsis, PEAM4 also caused inflorescence-to-flower transformations similar to constitutive AP1 expression, and was able to rescue the floral organ defects of the strong ap1-1 mutant. Our results suggest that the control of both floral meristem and floral organ identity by AP1 is not restricted to Arabidopsis, but is extended to species with diverse floral morphologies, such as pea.

Amino Acid Sequence↗
PubMed1999

Dimerization of Arabidopsis 14-3-3 proteins: structural requirements within the N-terminal domain and effect of calcium.

The structural requirements for dimerization of RCI14A and RCI14B, two 14-3-3 isoforms from Arabidopsis thaliana, have been analyzed by testing truncated forms of RCI14A for dimerization with full-length RCI14A and RCI14B. The results show that only the fourth helix of the truncated partner is essential for dimerization, which represents a difference from what is known for animal isoforms. On the other hand, the effect of calcium has been tested in RCI14A homodimerization. Millimolar concentrations of calcium exert a negative, dose-dependent effect that involves the C-terminal domain of RCI14A and might modulate interactions with other cellular components or among Arabidopsis 14-3-3 isoforms.

14-3-3 Proteins↗
PubMed1999

Identification of genes specifically expressed in cauliflower reproductive meristems. Molecular characterization of BoREM1.

Using the meristems of the cauliflower curd as a source of tissue and a series of subtractive hybridizations and amplification reactions, we have constructed a cDNA library highly enriched in cDNAs expressed in reproductive meristems. The analysis of a sample of 250 clones from this library identified 22 cDNA clones corresponding to genes specifically expressed in these cauliflower meristems. Apart from two clones that corresponded to APETALA1, and two other ones showing similarity to different aminoacyl-tRNA synthetases, the remaining clones showed no similarity to any sequence in the databases and may correspond to novel genes. One of these clones, BoREM1, was further characterized and found to correspond to a gene encoding a protein with features of regulatory proteins that follows a expression pattern very similar to the LEAFY transcripts.

Amino Acid Sequence↗
PubMed1999

Snakin-1, a peptide from potato that is active against plant pathogens.

A new type of antimicrobial peptide, snakin-1 (SN1), has been isolated from potato tubers and found to be active, at concentrations < 10 microM, against bacterial and fungal pathogens from potato and other plant species. The action of SN1 and potato defensin PTH1 was synergistic against the bacterium Clavibacter michiganensis subsp. sepedonicus and additive against the fungus Botrytis cinerea. Snakin-1 causes aggregation of both gram-positive and gram-negative bacteria. The peptide has 63 amino acid residues (M(r) 6,922), 12 of which are cysteines, and is unrelated to any previously isolated protein, although it is homologous to amino acid sequences deduced from cloned cDNAs that encode gibberellin-inducible mRNAs and has some sequence motifs in common with kistrin and other hemotoxic snake venoms. A degenerate oligonucleotide probe based on the internal sequence CCEECKC has been used to clone an SN1 cDNA. With the cDNA used as probe, one copy of the StSN1 gene per haploid genome has been estimated and expression of the gene has been detected in tubers, stems, axillary buds, and young floral buds. Expression levels in petals and carpels from fully developed flowers were much higher than in sepals and stamens. The expression pattern of gene StSN1 suggests that protein SN1 may be a component of constitutive defense barriers, especially those of storage and reproductive plant organs.

Amino Acid Sequence↗
PubMed1998

Low temperature regulates Arabidopsis Lhcb gene expression in a light-independent manner.

Low temperature treatment of dark-grown seedlings of Arabidopsis thaliana results in a rapid increase in the amount of mRNAs encoding for the major polypeptides of the light-harvesting complex of photosystem II (Lhcb1 genes). This increase is transient and seems to be due mainly to the accumulation of Lhcb1*3 transcripts, indicating that low temperature differentially regulates the expression of the Arabidopsis Lhcb1 gene family in the dark. A 1.34 kb fragment of the Lhcb1*3 promoter is sufficient to confer low temperature regulation to a reporter gene in transgenic Arabidopsis etiolated seedlings, suggesting that the regulation is occurring at the transcriptional level. The cold-induced accumulation of Lhcb1*3 mRNA is not part of a general response to stressful conditions since no accumulation is detected in response to water stress, anaerobiosis or salt stress. The amount of Lhcb1*3 mRNA decrease in response to exogenous abscisic acid (ABA) suggesting that this phytohormone acts as a negative regulator. Moreover, the accumulation of Lhcb1*3 mRNAs in cold-treated ABA deficient etiolated seedlings is higher than that of wild-type and ABA insensitive etiolated seedlings, indicating that low temperature regulation of Lhcb1*3 is not mediated by ABA.

Abscisic Acid↗
PubMed1997

Different roles of flowering-time genes in the activation of floral initiation genes in Arabidopsis.

We have analyzed double mutants that combine late-flowering mutations at four flowering-time loci (FVE, FPA, FWA, and FT) with mutations at the LEAFY (LFY), APETALA1 (AP1), and TERMINAL FLOWER1 (TFL1) loci involved in the floral initiation process (FLIP). Double mutants between ft-1 or fwa-1 and lfy-6 completely lack flowerlike structures, indicating that both FWA and FT act redundantly with LFY to control AP1. Moreover, the phenotypes of ft-1 ap1-1 and fwa-1 ap1-1 double mutants are reminiscent of the phenotype of ap1-1 cal-1 double mutants, suggesting that FWA and FT could also be involved in the control of other FLIP genes. Such extreme phenotypes were not observed in double mutants between fve-2 or fpa-1 and lfy-6 ap1-1. Each of these showed a phenotype similar to that of ap1-1 or lfy-6 mutants grown under noninductive photoperiods, suggesting a redundant interaction with FLIP genes. Finally, the phenotype of double mutants combining the late-flowering mutations with tfl1-2 were also consistent with the different roles of flowering-time genes.

Arabidopsis↗
PubMed1996

Manipulating photosynthesis.

The levels of individual photosynthetic proteins can be independently decreased by the Agrobacterium-mediated transformation of plants with antisense RNA constructs. Protocols for the introduction of such constructs into Agrobacterium, the Agrobacterium-mediated transformation of tobacco leaf disks, and the screening and analysis of the transgenic plants produced are described.

Agrobacterium tumefaciens↗
PubMed1994

The thylakoid-targeting domain of the chloroplast Rieske iron-sulfur protein is located in the N-terminal hydrophobic region of the mature protein.

The thylakoid-targeting domain of the Rieske FeS protein has been located in the N-terminal 55 amino acids of the mature protein by importing chimeric and truncated precursor proteins into isolated pea chloroplasts. A chimeric protein consisting of the presequence of ribulose-bisphosphate carboxylase/oxygenase (Rubisco) small subunit fused to the mature Rieske protein sequence was imported by chloroplasts, processed in the stroma, and translocated into the thylakoids, indicating that the thylakoid-targeting information was located within the mature Rieske protein. A truncated Rieske protein precursor consisting of the presequence and the N-terminal 55 amino acids of the mature protein was imported by chloroplasts and routed to the thylakoids, indicating that the thylakoid-targeting domain of the Rieske protein is located within the predominantly hydrophobic N-terminal region of the mature protein. Chimeric proteins consisting of this truncated Rieske protein precursor fused to the mature Rubisco small subunit and to plastocyanin were efficiently imported by chloroplasts and translocated across the thylakoid membrane. A proton-motive force was necessary for thylakoid translocation of the mature Rieske protein, the truncated Rieske protein, and the fusion protein consisting of the truncated Rieske protein and the mature Rubisco small subunit. In contrast, plastocyanin and the fusion of the truncated Rieske protein with plastocyanin were translocated across the thylakoid membrane in the presence of nigericin and valinomycin, indicating that the energy requirement for thylakoid translocation was conferred by the passenger protein and not by the thylakoid-targeting sequence.

Base Sequence↗
PubMed1993

Sequence analysis of thymidine kinase-defective mutants of equine herpesvirus-1 (EHV-1).

We have amplified, cloned and sequenced the gene encoding the thymidine kinase (TK) of a wild-type strain (Ab4) of equine herpesvirus-1 (EHV-1) and two mutants with defective TK activity isolated for resistance to penciclovir (PCV). One of the mutants, PR1, has suffered a 879-bp deletion which reduces the size of TK to 180 bp. The other mutant, PR3, has an adenine to cytosine mutation resulting in a Lys38-->Thr change. This mutation modifies the amino acid sequence of a domain involved in binding ATP, leading to non-detectable enzymatic activity. Lys38 thus appears to be essential for the activity of the TK of EHV-1.

Amino Acid Sequence↗
PubMed1992

Import and processing of the precursor of the Rieske FeS protein of tobacco chloroplasts.

cDNA clones encoding the precursor of the Rieske FeS protein of tobacco chloroplasts have been characterised and shown to derive from two different genes. The 5' ends of the corresponding transcripts have been cloned using primer extension and PCR. The nucleotide sequences of the cDNAs (and their 5' extensions) predict precursors for the tobacco proteins which differ in 4 amino acid residues out of a total of 228 residues and show high homology with the pea and spinach precursors. The tobacco precursor proteins contain N-terminal presequences of 49 amino acid residues which lack 17 amino acid residues present at the N-terminus of the spinach presequence. The 26 kDa precursor obtained by transcription and translation of one of these cDNAs in vitro was efficiently imported and correctly processed to the mature 20 kDa protein by isolated pea or tobacco chloroplasts. The precursor was also processed to its mature size by a peptidase present in the stroma of chloroplasts.

Amino Acid Sequence↗
PubMed1992

Import and processing of the precursor of the delta subunit of tobacco chloroplast ATP synthase.

A cDNA clone encoding the complete precursor of the delta subunit of chloroplast ATP synthase has been isolated from a tobacco (Nicotiana tabacum) leaf cDNA library in lambda gt11. The 880 bp insert encodes a polypeptide of 248 amino acid residues, of which 61 residues constitute an N-terminal presequence and 187 residues make up the mature delta subunit. Transcription and translation of the cDNA in vitro produced a protein of 29 kDa which was imported by isolated pea chloroplasts and processed to the mature 20 kDa subunit. The delta subunit precursor was processed to the mature size by a processing peptidase present in pea stromal extracts. Hybridisation of the cDNA to Southern blots of tobacco genomic DNA suggests the presence of two genes in the haploid genome.

Amino Acid Sequence↗
PubMed1992

Clustering of genes involved in nitrate assimilation in the cyanobacterium Synechococcus.

A region of the genome of the cyanobacterium Synechococcus R2, that bears a cluster of genes involved in nitrate assimilation, has been cloned and the relative positions of some of the genes in the region have been determined. Mutations generated by insertion of an antibiotic-resistance gene cassette into the gene encoding nitrite reductase are associated with reduced expression of nitrate reductase; cotranscription of nitrate assimilation genes in the cluster is inferred from this finding.

Blotting, Southern↗
PubMed1991

Use of a mutant strain of the cyanobacterium Synechococcus R2 for the determination of nitrate.

A sensitive procedure for the determination of nitrate within the 1- to 50-microM range is described. The method is based on the photoreduction of nitrate to nitrite by whole cells of a nitrite reductase-less mutant strain of the unicellular cyanobacterium Synechococcus R2. Cell suspensions of this cyanobacterium retain high levels of nitrate photoreduction activity for at least 2 months when maintained in the presence of dimethyl sulfoxide at -70 degrees C.

Cryopreservation↗
PubMed1990

Identification and cloning of a regulatory gene for nitrogen assimilation in the cyanobacterium Synechococcus sp. strain PCC 7942.

Twenty-seven mutants that were unable to assimilate nitrate were isolated from Synechococcus sp. strain PCC 7942. In addition to mutants that lacked nitrate reductase or nitrite reductase, seven pleiotropic mutants impaired in both reductases, glutamine synthetase, and methylammonium transport were also isolated. One of the pleiotropic mutants was complemented by transformation with a cosmid gene bank from wild-type strain PCC 7942. Three complementing cosmids were isolated, and a 3.1-kilobase-pair DNA fragment that was still able to complement the mutant was identified. The regulatory gene that was cloned (ntcA) appeared to be required for full expression of proteins subject to ammonium repression in Synechococcus sp.

Cloning, Molecular↗