Biomedical subjects

Carmen Castresana

Publications and source records attributed to Carmen Castresana.

9 recordsLinked to original sources

PubMed2006

Synthesis of 3-oxalinolenic acid and beta-oxidation-resistant 3-oxa-oxylipins.

3-Oxalinolenic acid (3-oxa-9(Z),12(Z),15(Z)-octadecatrienoic acid or (6(Z),9(Z),12(Z)-pentadecatrienyloxy)acetic acid) was synthesized from 5(Z),8(Z),11(Z),14(Z),17(Z)-eicosapentaenoic acid by a sequence involving the C15 aldehyde 3(Z),6(Z),9(Z),12(Z)-pentadecatetraenal as a key intermediate. Conversion of the aldehyde by isomerization and two steps of reduction afforded 6(Z),9(Z),12(Z)-pentadecatrienol, which was coupled to bromoacetate to afford after purification by HPLC >99%-pure 3-oxalinolenic acid in 10-15% overall yield. 3-Oxalinolenic acid was efficiently oxygenated by soybean lipoxygenase-1 into 3-oxa-13(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid, and this hydroperoxide could be further converted chemically into 3-oxa-13(S)-hydroxy-9(Z),11 (E),15(Z)-octadecatrienoic acid and 3-oxa-13-oxo-9(Z),11 (E),15(Z)-octadecatrienoic acid. The 3-oxa-hydroperoxide also served as the substrate for the plant enzymes allene oxide synthase, divinyl ether synthase, and hydroperoxide lyase to produce 3-oxa-12-oxo-10,15(Z)-phytodienoic acid and other 3-oxa-oxylipins that were characterized by MS. 3-Oxalinolenic acid was not oxygenated by 9-lipoxygenase from tomato but was converted at a slow rate into 3-oxa-9(S)-hydroperoxy-10(E),12(Z),15(Z)-octadecatrienoic acid by recombinant maize 9-lipoxygenase. Recombinant alpha-dioxygenase-1 from Arabidopsis thaliana catalyzed the conversion of 3-oxalinolenic acid into a 2-hydroperoxide, which underwent spontaneous degradation into a mixture of 6,9,12-pentadecatrienol and 6,9,12-pentadecatrienyl formate. A novel alpha-dioxygenase from the moss Physcomitrella patens was cloned and expressed and was found to display the same activity with 3-oxalinolenic acid as Arabidopsis thaliana alpha-dioxygenase-1. Lipoxygenase-generated 3-oxa-oxylipins are resistant toward beta-oxidation and have the potential for displaying enhanced biological activity in situations where activity is limited by metabolic degradation.

Chromatography, High Pressure Liquid↗

PubMed2005

Evaluation of the antimicrobial activities of plant oxylipins supports their involvement in defense against pathogens.

Plant oxylipins are a large family of metabolites derived from polyunsaturated fatty acids. The characterization of mutants or transgenic plants affected in the biosynthesis or perception of oxylipins has recently emphasized the role of the so-called oxylipin pathway in plant defense against pests and pathogens. In this context, presumed functions of oxylipins include direct antimicrobial effect, stimulation of plant defense gene expression, and regulation of plant cell death. However, the precise contribution of individual oxylipins to plant defense remains essentially unknown. To get a better insight into the biological activities of oxylipins, in vitro growth inhibition assays were used to investigate the direct antimicrobial activities of 43 natural oxylipins against a set of 13 plant pathogenic microorganisms including bacteria, oomycetes, and fungi. This study showed unequivocally that most oxylipins are able to impair growth of some plant microbial pathogens, with only two out of 43 oxylipins being completely inactive against all the tested organisms, and 26 oxylipins showing inhibitory activity toward at least three different microbes. Six oxylipins strongly inhibited mycelial growth and spore germination of eukaryotic microbes, including compounds that had not previously been ascribed an antimicrobial activity, such as 13-keto-9(Z),11(E),15(Z)-octadecatrienoic acid and 12-oxo-10,15(Z)-phytodienoic acid. Interestingly, this first large-scale comparative assessment of the antimicrobial effects of oxylipins reveals that regulators of plant defense responses are also the most active oxylipins against eukaryotic microorganisms, suggesting that such oxylipins might contribute to plant defense through their effects both on the plant and on pathogens, possibly through related mechanisms.

Anti-Infective Agents↗

PubMed2005

Alpha-dioxygenases.

Alpha-dioxygenases constitute a family of fatty acid-metabolizing enzymes recently discovered in plants. The present paper gives a brief overview of the literature dealing with these enzymes and additionally reports the new finding of an alpha-dioxygenase in the moss, Physcomitrella patens, and some properties of this enzyme.

Amino Acid Sequence↗

PubMed2005

Arabidopsis SHMT1, a serine hydroxymethyltransferase that functions in the photorespiratory pathway influences resistance to biotic and abiotic stress.

We found that a recessive mutation, shmt1-1, causes aberrant regulation of cell death resulting in chlorotic and necrotic lesion formation under a variety of environmental conditions. Salicylic acid-inducible genes and genes involved in H(2)O(2) detoxification were expressed constitutively in shmt1-1 plants in direct correlation with the severity of the lesions. The shmt1-1 mutants were more susceptible than control plants to infection with biotrophic and necrotrophic pathogens, developing severe infection symptoms in a high percentage of infected leaves. In addition, mutants carrying shmt1-1 or a loss-of-function shmt1-2 allele, were smaller and showed a greater loss of chlorophyll and greater accumulation of H(2)O(2) than wild-type plants when subjected to salt stress. SHMT1 was map-based cloned and found to encode a serine hydroxymetyltransferase (SHMT1) involved in the photorespiratory pathway. Our results indicate that this enzymatic activity plays a critical role in controlling the cell damage provoked by abiotic stresses such as high light and salt and in restricting pathogen-induced cell death, supporting the notion that photorespiration forms part of the dissipatory mechanisms of plants to minimize production of reactive oxygen species (ROS) at the chloroplast and to mitigate oxidative damage. Moreover, results shown here indicate that whereas production of ROS is an essential component of the hypersensitive defense response, the excessive accumulation of these toxic compounds impairs cell death containment and counteracts the effectiveness of the plant defenses to restrict pathogen infection.

Arabidopsis↗

PubMed2004

A Pinus radiata AAA-ATPase, the expression of which increases with tree ageing.

Age-dependent changes in gene expression profiles were studied in vegetative Pinus radiata buds by means of differential display. Among several candidate cDNAs, a 327 bp fragment that shows high homology with an Arabidopsis thaliana 20S proteasome ATPase designated RPT5a was found. Northern hybridization confirmed that the accumulation of this transcript increases with tree ageing, suggesting a possible role of this AAA-ATPase gene in development-related specific proteolysis.

Adenosine Triphosphatases↗

PubMed2003

Activation of the fatty acid alpha-dioxygenase pathway during bacterial infection of tobacco leaves. Formation of oxylipins protecting against cell death.

A pathogen-induced oxygenase showing homology to prostaglandin endoperoxide synthases-1 and -2 was recently characterized by in vitro experiments as a fatty acid alpha-dioxygenase catalyzing formation of unstable 2(R)-hydroperoxy fatty acids. To study the activity of this enzyme under in vivo conditions and to elucidate the fate of enzymatically produced 2-hydroperoxides, leaves of tobacco were analyzed for the presence of alpha-dioxygenase-generated compounds as well as for lipoxygenase (LOX) products and free fatty acids. Low basal levels of 2-hydroxylinolenic acid (0.4 nmol/g leaves fresh weight) and 8,11,14-heptadecatrienoic acid (0.1 nmol/g) could be demonstrated. These levels increased strongly upon infection with the bacterium Pseudomonas syringae pv syringae (548 and 47 nmol/g, respectively). Transgenic tobacco plants overexpressing alpha-dioxygenase were developed, and incompatible infection of such plants led to a dramatic elevation of 2-hydroxylinolenic acid (1778 nmol/g) and 8,11,14-heptadecatrienoic acid (86 nmol/g), whereas the levels of LOX products were strongly decreased. Further analysis of oxylipins in infected leaves revealed the presence of a number of 2-hydroxy fatty acids differing with respect to chain length and degree of unsaturation as well as two new doubly oxygenated oxylipins identified as 2(R),9(S)-dihydroxy-10(E),12(Z),15(Z)-octadecatrienoic acid and 2(R),9(S)-dihydroxy-10(E),12(Z)-octadecadienoic acid. alpha-Dioxygenase-generated 2-hydroxylinolenic acid, and to a lesser extent lipoxygenase-generated 9-hydroxyoctadecatrienoic acid, exerted a tissue-protective effect in bacterially infected tobacco leaves.

Bacterial Infections↗

PubMed2002

Fatty acid alpha-dioxygenases.

This paper will briefly review the biochemistry, molecular biology and functionality of alpha-dioxygenases from tobacco, Arabidopsis, cucumber, pea, rice and algae. Alpha-dioxygenase treated in this review has emerged as a third group of fatty acid dioxygenases along with lipoxygenases and endoperoxide synthases.

Algal Proteins↗

PubMed2002

Involvement of the Arabidopsis alpha-DOX1 fatty acid dioxygenase in protection against oxidative stress and cell death.

alpha-dioxygenases (alpha-DOXs) catalyze the primary oxygenation of fatty acids into a newly identified group of oxylipins. Here we show that expression of the Arabidopsis alpha-DOX1 gene is induced in response to both incompatible and compatible bacterial infections. However, the level of alpha-DOX1 mRNA and dioxygenase activity appears earlier and reaches higher values when infection promotes a hypersensitive reaction. Furthermore, whereas gene expression is confined to necrotic lesions during the hypersensitive response, it occurs throughout the chlorotic area during a compatible interaction. Accumulation of alpha-DOX1 transcripts is impaired in SA-compromised plants and induced by SA and by chemicals generating nitric oxide (NO), intracellular superoxide or singlet oxygen, three signals mediating host cell death. Transgenic plants with altered levels of alpha-dioxygenase react like wild-type plants to a compatible pathogen. In contrast, plants with reduced activity develop a more rapid and severe necrotic response than wild-type plants to incompatible bacteria and paraquat treatment, respectively, and a milder response when alpha-DOX1 is overproduced. Our results suggest that plant alpha-dioxygenases are used to generate lipid-derived molecules for a process that protects plant tissues from oxidative stress and cell death.

Abscisic Acid↗

PubMed2002

AtCOX17, an Arabidopsis homolog of the yeast copper chaperone COX17.

We have identified a new plant gene, AtCOX17, encoding a protein that shares sequence similarity to COX17, a Cu-binding protein from yeast (Saccharomyces cerevisiae) and vertebrates that mediates the delivery of Cu to the mitochondria for the assembly of a functional cytochrome oxidase complex. The newly characterized Arabidopsis protein has six Cys residues at positions corresponding to those known to coordinate Cu binding in the yeast homolog. Moreover, we show that the Arabidopsis COX17 cDNA complements a COX17 mutant of yeast restoring the respiratory deficiency associated with that mutation. These two lines of evidence indicate that the plant protein identified here is a functional equivalent of yeast COX17 and might serve as a Cu delivery protein for the plant mitochondria. COX17 was identified by investigating the hypersensitive response-like necrotic response provoked in tobacco (Nicotiana tabacum) leaves after harpin inoculation. AtCOX17 expression was activated by high concentrations of Cu, bacterial inoculation, salicylic acid treatment, and treatments that generated NO and hydrogen peroxide. All of the conditions inducing COX17 are known to inhibit mitochondrial respiration and to produce an increase of reactive oxygen species, suggesting that gene induction occurs in response to stress situations that interfere with mitochondrial function.

Amino Acid Sequence↗