Activity of phosphatidylcholine-transfer protein from spinach (Spinacia oleracea) leaves with mitochondria and chloroplasts.
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ABSTRACT:
SUBMITTER: Julienne M
PROVIDER: S-EPMC1163194 | biostudies-other | 1981 Sep
REPOSITORIES: biostudies-other
Similar Datasets
Project description:When intact spinach chloroplasts were supplied with [32P]Pi, stromal protein phosphorylation was found to occur in the dark. On illumination the thylakoid protein kinase was activated and the amount of label found in thylakoid proteins quickly exceeded that incorporated into stromal protein, such that the latter was found to account for only 10-15% of the total radioactivity bound to chloroplast proteins after 5 min illumination. The rate of phosphorylation of stromal polypeptides was unchanged by light. After SDS/polyacrylamide-gel electrophoresis, more than 15 labelled polypeptides of stromal origin were observed. A polypeptide with an Mr of approx. 70 000 had the highest specific activity of labelling. Both the large and small subunits of the ribulose-1,5-bisphosphate carboxylase were phosphorylated. The level of phosphorylation of stromal protein was increased by CO2 fixation in intact chloroplasts. This increase was not observed in the absence of NaHCO3 or in the presence of the phosphoribulokinase inhibitor DL-glyceraldehyde. These effects appeared to be largely due to changes in the phosphorylation state of the large and small subunits of ribulose-1,5-bisphosphate carboxylase. Studies with the reconstituted chloroplast system showed that the thylakoid protein kinase(s) played no part in the phosphorylation of stromal protein. The rate and level of phosphorylation of stromal protein was unaffected by the activation state of the thylakoid protein kinase and was unchanged when thylakoids were omitted from the reaction medium. The phosphorylation of stromal proteins is therefore catalysed by a discrete soluble protein kinase.
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Project description:Diacylgalactosylglycerol synthesis was a prerequisite for the incorporation of [1-14C]-acetate into linoleate and alpha-linolenate of isolated spinach (Spinacia oleracea) chloroplasts. Oleate at position 1 of diacylgalactosylglycerol was desaturated to linoleate and alpha-linolenate both in the light and in the dark. Some desaturation of palmitate was also observed after prolonged incubations.
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Project description:During the course of NH4+ (or NO2-)-plus-alpha-oxoglutarate-dependent O2 evolution in spinach (Spinacia oleracea) chloroplasts, glutamate was continuously excreted out of the chloroplasts. Under these conditions, for each molecule of NO2- or NH4+ which disappeared, one molecule of glutamate accumulated in the medium and the concentration of glutamate in the stroma space was maintained constant. SO4(2-) (or SO3(2-) behave as inhibitors of NH4+ incorporation into glutamate by intact chloroplasts. This considerable inhibition of glutamate synthesis by SO4(2-) was correlated with a rapid decline in the stromal Pi concentration. The reloading of stromal Pi with either external Pi or PPi4- relieved SO4(2-)-induced inhibition of glutamate synthesis by intact chloroplasts. It was concluded that SO4(2-) induced a rapid efflux of stromal Pi out of the chloroplast, leading to a limitation of ATP synthesis and therefore to an arrest of ATP-dependent glutamine synthetase functioning.
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Project description:Essentially chlorophyll-free mitochondria from photosynthetic (leaf) and non-photosynthetic tissue (petiole) were isolated from spinach (Spinacia oleracea). Leaf mitochondria were found to contain more phosphatidylcholine than phosphatidylethanolamine compared with petiole mitochondria. Galactolipids were found in small and equal amounts (5 mol of galactolipids/100 mol of galactolipids and phospholipids) in both leaf and petiole mitochondria. Fatty acid composition showed a significant difference in the amounts of C18:2 and C18:3 acids. The C18:2/C18:3 ratio was more than twice as high in all of the phospholipids studied from petiole mitochondria compared with the ratio in leaf mitochondria. More than 50% (mol/100 mol) of the fatty acids in the major lipids (phosphatidylcholine, phosphatidylethanolamine and cardiolipin) in petiole mitochondria were C18:2. In the minor lipids (phosphatidylinositol and phosphatidylglycerol), C16:0 dominated in both leaf and petiole mitochondria.
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Project description:Spinach (Spinacia oleracea) has cold tolerant but heat sensitive characteristics. The spinach variety 'Island,' is suitable for summer periods. There is lack molecular information available for spinach in response to heat stress. In this study, high throughput de novo transcriptome sequencing and gene expression analyses were carried out at different spinach variety 'Island' leaves (grown at 24?°C (control), exposed to 35?°C for 30?min (S1), and 5?h (S2)). A total of 133,200,898 clean reads were assembled into 59,413 unigenes (average size 1259.55?bp). 33,573 unigenes could match to public databases. The DEG of controls vs S1 was 986, the DEG of control vs S2 was 1741 and the DEG of S1 vs S2 was 1587. Gene Ontology (GO) and pathway enrichment analysis indicated that a great deal of heat-responsive genes and other stress-responsive genes were identified in these DEGs, suggesting that the heat stress may have induced an extensive abiotic stress effect. Comparative transcriptome analysis found 896 unique genes in spinach heat response transcript. The expression patterns of 13 selected genes were verified by RT-qPCR (quantitative real-time PCR). Our study found a series of candidate genes and pathways that may be related to heat resistance in spinach.
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Project description:Preparations of acetyl-CoA carboxylase [acetyl-CoA-carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] have been obtained from the plastids of avocado (Persea americana) fruit mesocarp and from spinach (Spinacia oleracea) chloroplasts. Both preparations required bovine serum albumin, HCO3-, citrate and glycerol for stabilization. The molecular weight of the avocado enzyme was about 6.5 X 10(5) on the basis of 1 mol of biotin/mol of enzyme, the behaviour of both enzymes on gel filtration being in accord with such a value. Removal of the stabilizing bovine serum albumin resulted in the loss of a biotin-containing fragment from the avocado enzyme. Citrate stabilized the enzyme at 10 mM and activated it optimally at 3.0 mM, effecting an approx. 2-fold increase in Vmax. It is suggested that in vivo the enzyme may be located within the chloroplast lamellae.
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Project description:Mitochondria isolated from spinach (Spinacia oleracea) leaves oxidized glycine with a stoichiometry of CO2 evolution to O2 uptake of 2 : 1. In the absence of added substrate, the mitochondria exhibited an extremely low endogenous rate of O2 uptake.
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Project description:Spinach (Spinacia oleracea L.) is an economically important vegetable crop. Here we describe the complete mitochondrial DNA sequence of spinach, which has a length of 329,613 bp and a GC content of 43.4%. It is separated by a pair of directly repeated elements of 7286 bp, to form a large single copy region of 229,375 bp and a small single copy region of 85,666 bp. The genome contains 29 protein-coding genes, 4 pseudogenes, 24 tRNA genes, and 3 rRNA genes. A phylogenetic analysis revealed that spinach was closely related to Beta vulgaris (sugar beet), both belonging to the Amaranthaceae family.
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Project description:Spinach (Spinacia oleracea L.) is an economically important and globally consumed popular leafy vegetable that is heat-sensitive. Heat stress caused by global climate change is one of the primary deleterious elements limiting spinach production worldwide. Little work has been done to explore the heat-responsive mechanisms of spinach under high temperature-induced stress. In the present study, we used iTRAQ-based proteomic and transcriptomic approaches to investigate physiological, metabolic, and proteomic responses of spinach in response to day / night temperature of 35°C / 25°C compared to 20°C / 15°C for 4 days. A total of 3,543 differentially expressed genes (DEGs) were detected using transcriptome sequencing, of which 2,086 DEGs were downregulated and 1,457 were upregulated. The DEGs were mainly involved in superoxide dismutase activity, catalase, and peroxidase activity. A total of 3,246 differentially abundant proteins were detected using iTAQ-based quantitative proteomic approach, from which 567 differentially expressed proteins (DEPs) (277 upregulated and 290 downregulated) were identified. DEPs were mainly assigned to pathways related to metabolism, signal transduction, protein degradation, defense, and antioxidant. Four genes - superoxide dismutase (SOD, LOC110788339), catalase (CAT, LOC110790286), peroxidase (POD, LOC110775253), and heat shock protein (HSP, LOC110799288) - were validated using quantitative real-time PCR (qRT-PCR) to verify the proteomic and transcriptomic analyses, showing different transcriptional and translational expression levels. The findings of this study provide a fundamental understanding of the metabolic pathways and biological processes that control adaptation to heat stress in spinach, and provide novel insight into the development of heat-tolerant spinach.
2020-06-24 | GSE153070 | GEO
Project description:Spinacia oleracea strain:Spinach Raw sequence reads
| PRJNA576552 | ENA