Search results for "Peas"

Expression of the pea S -adenosylmethionine decarboxylase gene is involved in developmental and environmental responses

2002

A cDNA, able to complement the S-adenosyl-L-methionine decarboxylase (SAMdC; EC 4.1.1.50)-defective yeast strain Y342, has been isolated from pea (Pisum sativum L.). Expression of the SAMdC gene was characterised during pea development. Northern analysis showed a differential expression of the pea SAMdC gene in vegetative and reproductive tissues. The highest SAMdC mRNA levels were found in undifferentiated callus and tissues with high rates of cell division, and at the onset of fruit development. SAMdC expression was also induced in senescing ovaries, probably in relation to an accumulation of spermine during ovary senescence. Finally, the levels of SAMdC transcripts in leaves and shoots w…

Hormonal regulation of S-adenosylmethionine synthase transcripts in pea ovaries

1996

Two cDNA clones coding for S-adenosyl-L-methionine synthase (SAMs, EC 2.5.1.6) have been isolated from a cDNA library of gibberellic acid-treated unpollinated pea ovaries. Both cDNAs were sequenced showing a high degree of identity but coding for different SAMs polypeptides. The presence of two SAMs genes in pea was further confirmed by Southern analysis. Expression of the SAMs genes in the pea plant was found at different levels in vegetative and reproductive tissues. We characterized the expression levels of SAMs genes during the development or senescence of pea ovaries. Northern analysis showed that transcription of SAMs genes in parthenocarpic fruits was upregulated by auxins in the sam…

Large-scale gene discovery in the pea aphid Acyrthosiphon pisum (Hemiptera)

2006

A large-scale sequencing analysis of the Hemiptera Acyrthosiphon pisumexpressed sequence tags corresponding to about 12,000 unique transcripts is described, along with an in silico profiling analysis that identifies 135 aphid tissue-specific transcripts.

BOTANICAL CONTRIBUTION TO ARCHAEOLOGICAL LAND EVALUATION IN THE FP7 MEMOLA PROJECT

2014

Determination of relative chlorophyll binding affinities in the major light-harvesting chlorophyll a/b complex.

2002

The major light-harvesting complex (LHCIIb) of photosystem II can be reconstituted in vitro from its recombinant apoprotein in the presence of a mixture of carotenoids and chlorophylls a and b. By varying the chlorophyll a/b ratio in the reconstitution mixture, the relative amounts of chlorophyll a and chlorophyll b bound to LHCIIb can be changed. We have analyzed the chlorophyll stoichiometry in recombinant wild type and mutant LHCIIb reconstituted at different chlorophyll a/b ratios in order to assess relative affinities of the chlorophyll-binding sites. This approach reveals five sites that exclusively bind chlorophyll b. Another site exhibits a slight preference of chlorophyll b over ch…

Random mutations directed to transmembrane and loop domains of the light-harvesting chlorophyll a/b protein: impact on pigment binding.

1999

The major light-harvesting complex of photosystem II (LHCII) can be reconstituted in vitro by folding its bacterially expressed apoprotein, Lhcb, in detergent solution in the presence of chlorophylls and carotenoids. To compare the impact of alpha-helical transmembrane domains and hydrophilic loop domains of the apoprotein on complex formation and stability, we introduced random mutations into a segment of the protein comprising the stromal loop, the third (C-proximal) transmembrane helix, and part of the amphipathic helix in the C-terminal domain. The mutant versions of Lhcb were screened for the loss of their ability to form stable LHCII upon reconstitution in vitro. Most steps during the…

Exchange of Pigment-Binding Amino Acids in Light-Harvesting Chlorophyll a/b Protein

1999

Four amino acids in the major light-harvesting chlorophyll (Chl) a/b complex (LHCII) that are thought to coordinate Chl molecules have been exchanged with amino acids that presumably cannot bind Chl. Amino acids H68, Q131, Q197, and H212 are positioned in helixes B, C, A, and D, respectively, and, according to the LHCII crystal structure [Kühlbrandt, W., et al. (1994) Nature 367, 614-621], coordinate the Chl molecules named a(5), b(6), a(3), and b(3). Moreover, a double mutant was analyzed carrying exchanges at positions E65 and H68, presumably affecting Chls a(4) and a(5). All mutant proteins could be reconstituted in vitro with pigments, although the thermal stability of the resulting mut…

Cadmium accumulation and buffering of cadmium-induced stress by arbuscular mycorrhiza in three Pisum sativum L. genotypes

2002

The role of arbuscular mycorrhiza in reducing Cd stress was investigated in three genotypes of Pisum sativum L. (cv. Frisson, VIR4788, VIR7128), grown in soil/sand pot cultures in the presence and absence of 2-3 mg kg(-1) bioavailable Cd, and inoculated or not with the arbuscular mycorrhizal fungus Glomus intraradices. Shoot, root and pod biomass were decreased by Cd in non-mycorrhizal plants. The presence of mycorrhiza attenuated the negative effect of Cd so that shoot biomass and activity of photosystem II, based on chlorophyll a fluorescence, were not significantly different between mycorrhizal plants growing in the presence or absence of the heavy metal (HM). Total P concentrations were…

Water-Soluble Chlorophyll Protein (WSCP) Stably Binds Two or Four Chlorophylls

2017

Water-soluble chlorophyll proteins (WSCPs) of class IIa from Brassicaceae form tetrameric complexes containing one chlorophyll (Chl) per apoprotein but no carotenoids. The complexes are remarkably stable toward dissociation and protein denaturation even at 100 °C and extreme pH values, and the Chls are partially protected against photooxidation. There are several hypotheses that explain the biological role of WSCPs, one of them proposing that they function as a scavenger of Chls set free upon plant senescence or pathogen attack. The biochemical properties of WSCP described in this paper are consistent with the protein acting as an efficient and flexible Chl scavenger. At limiting Chl concen…

Early folding events during light harvesting complex II assembly in vitro monitored by pulsed electron paramagnetic resonance

2016

Efficient energy transfer in the major light harvesting complex II (LHCII) of green plants is facilitated by the precise alignment of pigments due to the protein matrix they are bound to. Much is known about the import of the LHCII apoprotein into the chloroplast via the TOC/TIC system and its targeting to the thylakoid membrane but information is sparse about when and where the pigments are bound and how this is coordinated with protein folding. In vitro, the LHCII apoprotein spontaneously folds and binds its pigments if the detergent-solubilized protein is combined with a mixture of chlorophylls a and b and carotenoids. In the present work, we employed this approach to study apoprotein fo…