Plant Lipid-Transfer Proteins (LTPs) exhibit the ability to reversibly bind/transport lipids in v... more Plant Lipid-Transfer Proteins (LTPs) exhibit the ability to reversibly bind/transport lipids in vitro. LTPs have been involved in diverse physiological processes but conclusive evidence on their role has only been presented for a few members, none of them related to seed physiology. Arabidopsis seeds rely on storage oil breakdown to supply carbon skeletons and energy for seedling growth. Here, Arabidopsis ltp3 mutant was analysed for its ability to germinate and for seedling establishment. Ltp3 showed delayed germination and reduced germination frequency. Seedling growth appeared reduced in the mutant but this growth restriction was rescued by the addition of an exogenous carbon supply, suggesting a defective oil mobilization. Lipid breakdown analysis during seedling growth revealed a differential profile in the mutant compared to the wild type. The involvement of LTP3 in germination and seedling growth and its relationship with the lipid transfer ability of this protein is discussed.
Nitric oxide (NO) is a major plant signaling molecule that plays key roles during plant-pathogen ... more Nitric oxide (NO) is a major plant signaling molecule that plays key roles during plant-pathogen interactions and plant development. Previous work showed the participation of NO in the development and lignin composition of sunflower roots. Thereby, we have hypothesized that NO applications could control the attack of the fungal pathogen Verticillium dahliae in sunflower. Seedlings growing hydroponically were pretreated with NO donors and further inoculated with the fungus. Evaluation of disease symptoms showed that NO pretreatments could not reduce Verticillium wilt. Strikingly, NO donors appear to promote the fungal infection. These results indicate that NO applications were unable to protect sunflower from Verticillium attack and highlight the role played by the fine tuning regulation of NO levels required to balance plant responses between development and defense.
Ha-AP10 is a basic antifungal peptide from sunflower seeds (Helianthus annuus antifungal peptide ... more Ha-AP10 is a basic antifungal peptide from sunflower seeds (Helianthus annuus antifungal peptide of 10 kDa) belonging to the family of plant lipid transfer proteins. We report here its expression in E. coli [Glutathione S-transferase (GST) system] and its phosphorylation by endogenous membrane-bound calcium-dependent protein kinases.
A mitochondrial plasmid of 1,939 bp (P2) from a cytoplasmic male-sterile line of sunflower has be... more A mitochondrial plasmid of 1,939 bp (P2) from a cytoplasmic male-sterile line of sunflower has been cloned and sequenced. It presents 437 bp of near-perfect homology to the 1.4-kb mitochondrial plasmid P1 from sunflower. Sequences homologous to P2 were found in nuclear DNA. P2 was transcribed into a major 980-nucleotide (nt) RNA molecule and two minor transcripts of 570 and
ABSTRACT Helianthinins are storage proteins present in Helianthus annuus seeds, belonging to the ... more ABSTRACT Helianthinins are storage proteins present in Helianthus annuus seeds, belonging to the 11S globulin family. Here we describe that a fraction of the helianthinins is phosphorylated. This conclusion is supported by different criteria, including identification by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry of major protein bands revealed with a specific dye for phosphoproteins, anti-phosphoserine antibody and binding to a phosphoprotein affinity matrix. Moreover, we show that the phosphorylation status of helianthinins changes following germination.
Many proteins exerting antifungal activity in vitro have been isolated although in certain cases ... more Many proteins exerting antifungal activity in vitro have been isolated although in certain cases their contribution in plant resistance to fungal attack is unclear. Screening for antifungal proteins from sunflower seeds, we have detected a basic polypeptide (Ha-AP15) homologous to the previously described storage protein 2S albumin. Results reported here indicate that Ha-AP15 exerts a weak inhibition of hyphal elongation
A 16-kDa protein was isolated from Helianthus annuus flowers by its ability to inhibit the germin... more A 16-kDa protein was isolated from Helianthus annuus flowers by its ability to inhibit the germination of fungal spores. This protein, SAP16, displays an associated activity of trypsin inhibitor and was further purified to apparent homogeneity by affinity chromatography on ...
Trypomastigote cells of Trypanosoma cruzi incubated with [U-14C]glucose accumulated dolichol-P-P-... more Trypomastigote cells of Trypanosoma cruzi incubated with [U-14C]glucose accumulated dolichol-P-P-linked Man7GlcNAc2 and Man9GlcNAc2. Evidence is presented indicating that both oligosaccharides were transferred to asparagine residues in proteins. On the other hand, intracellular amastigotes behaved as epimastigotes, i.e., only Man9GlcNAc2 accumulated and was transferred to proteins under similar incubation conditions. Intracellular amastigotes differed, therefore, from amastigotes obtained from an axenic culture, which behaved as trypomastigotes. A similar processing of protein-linked Man9GlcNAc2 and Man8GlcNAc2 occurred in epimastigotes and trypomastigotes but the structure of the main Man7GlcNAc2 isomer produced by demannosylation of the above mentioned oligosaccharides differed from that of the Man7GlcNAc2 transferred in trypomastigotes and amastigotes from axenic cultures. The infective trypomastigote stage of the parasite showed, therefore, an alteration in the mechanism of protein N-glycosylation when compared to the other stages, namely epimastigote (insect vector stage) and amastigote (mammalian intracellular stage). Complex-type, asparagine-bound oligosaccharides were found to be synthesized in both epimastigotes and trypomastigotes but the amounts of those compounds were extremely low when compared to those of high mannose-type oligosaccharides.
Nonspecific lipid transfer proteins (nsLTPs) belong to a large family of plant proteins whose fun... more Nonspecific lipid transfer proteins (nsLTPs) belong to a large family of plant proteins whose function in vivo remains unknown. In this research, we studied a LTP previously isolated from sunflower seeds (Ha-AP10), which displays strong antimicrobial activity against a model fungus. The protein is present during at least the first 5 days of germination, and tissue printing experiments revealed the homogeneous distribution of the protein in the cotyledons. Here we report that Ha-AP10 exerts a weak inhibitory effect on the growth of Alternaria alternata, a fungus that naturally attacks sunflower seeds. These data put into question the contribution of Ha-AP10 as an antimicrobial protein of direct effect on pathogenic fungus, and rather suggest a function related to the mobilization of lipid reserves. We also show that the levels of Ha-AP10 in germinating seeds increase upon salt stress, fungal infection and ABA treatment, indicating that it somehow participates in the adaptative responses of germinating sunflower seeds.
Plant Lipid-Transfer Proteins (LTPs) exhibit the ability to reversibly bind/transport lipids in v... more Plant Lipid-Transfer Proteins (LTPs) exhibit the ability to reversibly bind/transport lipids in vitro. LTPs have been involved in diverse physiological processes but conclusive evidence on their role has only been presented for a few members, none of them related to seed physiology. Arabidopsis seeds rely on storage oil breakdown to supply carbon skeletons and energy for seedling growth. Here, Arabidopsis ltp3 mutant was analysed for its ability to germinate and for seedling establishment. Ltp3 showed delayed germination and reduced germination frequency. Seedling growth appeared reduced in the mutant but this growth restriction was rescued by the addition of an exogenous carbon supply, suggesting a defective oil mobilization. Lipid breakdown analysis during seedling growth revealed a differential profile in the mutant compared to the wild type. The involvement of LTP3 in germination and seedling growth and its relationship with the lipid transfer ability of this protein is discussed.
Nitric oxide (NO) is a major plant signaling molecule that plays key roles during plant-pathogen ... more Nitric oxide (NO) is a major plant signaling molecule that plays key roles during plant-pathogen interactions and plant development. Previous work showed the participation of NO in the development and lignin composition of sunflower roots. Thereby, we have hypothesized that NO applications could control the attack of the fungal pathogen Verticillium dahliae in sunflower. Seedlings growing hydroponically were pretreated with NO donors and further inoculated with the fungus. Evaluation of disease symptoms showed that NO pretreatments could not reduce Verticillium wilt. Strikingly, NO donors appear to promote the fungal infection. These results indicate that NO applications were unable to protect sunflower from Verticillium attack and highlight the role played by the fine tuning regulation of NO levels required to balance plant responses between development and defense.
Ha-AP10 is a basic antifungal peptide from sunflower seeds (Helianthus annuus antifungal peptide ... more Ha-AP10 is a basic antifungal peptide from sunflower seeds (Helianthus annuus antifungal peptide of 10 kDa) belonging to the family of plant lipid transfer proteins. We report here its expression in E. coli [Glutathione S-transferase (GST) system] and its phosphorylation by endogenous membrane-bound calcium-dependent protein kinases.
A mitochondrial plasmid of 1,939 bp (P2) from a cytoplasmic male-sterile line of sunflower has be... more A mitochondrial plasmid of 1,939 bp (P2) from a cytoplasmic male-sterile line of sunflower has been cloned and sequenced. It presents 437 bp of near-perfect homology to the 1.4-kb mitochondrial plasmid P1 from sunflower. Sequences homologous to P2 were found in nuclear DNA. P2 was transcribed into a major 980-nucleotide (nt) RNA molecule and two minor transcripts of 570 and
ABSTRACT Helianthinins are storage proteins present in Helianthus annuus seeds, belonging to the ... more ABSTRACT Helianthinins are storage proteins present in Helianthus annuus seeds, belonging to the 11S globulin family. Here we describe that a fraction of the helianthinins is phosphorylated. This conclusion is supported by different criteria, including identification by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry of major protein bands revealed with a specific dye for phosphoproteins, anti-phosphoserine antibody and binding to a phosphoprotein affinity matrix. Moreover, we show that the phosphorylation status of helianthinins changes following germination.
Many proteins exerting antifungal activity in vitro have been isolated although in certain cases ... more Many proteins exerting antifungal activity in vitro have been isolated although in certain cases their contribution in plant resistance to fungal attack is unclear. Screening for antifungal proteins from sunflower seeds, we have detected a basic polypeptide (Ha-AP15) homologous to the previously described storage protein 2S albumin. Results reported here indicate that Ha-AP15 exerts a weak inhibition of hyphal elongation
A 16-kDa protein was isolated from Helianthus annuus flowers by its ability to inhibit the germin... more A 16-kDa protein was isolated from Helianthus annuus flowers by its ability to inhibit the germination of fungal spores. This protein, SAP16, displays an associated activity of trypsin inhibitor and was further purified to apparent homogeneity by affinity chromatography on ...
Trypomastigote cells of Trypanosoma cruzi incubated with [U-14C]glucose accumulated dolichol-P-P-... more Trypomastigote cells of Trypanosoma cruzi incubated with [U-14C]glucose accumulated dolichol-P-P-linked Man7GlcNAc2 and Man9GlcNAc2. Evidence is presented indicating that both oligosaccharides were transferred to asparagine residues in proteins. On the other hand, intracellular amastigotes behaved as epimastigotes, i.e., only Man9GlcNAc2 accumulated and was transferred to proteins under similar incubation conditions. Intracellular amastigotes differed, therefore, from amastigotes obtained from an axenic culture, which behaved as trypomastigotes. A similar processing of protein-linked Man9GlcNAc2 and Man8GlcNAc2 occurred in epimastigotes and trypomastigotes but the structure of the main Man7GlcNAc2 isomer produced by demannosylation of the above mentioned oligosaccharides differed from that of the Man7GlcNAc2 transferred in trypomastigotes and amastigotes from axenic cultures. The infective trypomastigote stage of the parasite showed, therefore, an alteration in the mechanism of protein N-glycosylation when compared to the other stages, namely epimastigote (insect vector stage) and amastigote (mammalian intracellular stage). Complex-type, asparagine-bound oligosaccharides were found to be synthesized in both epimastigotes and trypomastigotes but the amounts of those compounds were extremely low when compared to those of high mannose-type oligosaccharides.
Nonspecific lipid transfer proteins (nsLTPs) belong to a large family of plant proteins whose fun... more Nonspecific lipid transfer proteins (nsLTPs) belong to a large family of plant proteins whose function in vivo remains unknown. In this research, we studied a LTP previously isolated from sunflower seeds (Ha-AP10), which displays strong antimicrobial activity against a model fungus. The protein is present during at least the first 5 days of germination, and tissue printing experiments revealed the homogeneous distribution of the protein in the cotyledons. Here we report that Ha-AP10 exerts a weak inhibitory effect on the growth of Alternaria alternata, a fungus that naturally attacks sunflower seeds. These data put into question the contribution of Ha-AP10 as an antimicrobial protein of direct effect on pathogenic fungus, and rather suggest a function related to the mobilization of lipid reserves. We also show that the levels of Ha-AP10 in germinating seeds increase upon salt stress, fungal infection and ABA treatment, indicating that it somehow participates in the adaptative responses of germinating sunflower seeds.
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