| 1. |
- Albertsson, Per-Åke
(författare)
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A quantitative model of the domain structure of the photosynthetic membrane
- 2001
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Ingår i: Trends in Plant Science. - 1360-1385. ; 6:8, s. 349-358
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Tidskriftsartikel (refereegranskat)abstract
- A model is presented that gives a quantitative picture of the distribution of the photosynthetic components in the photosynthetic membrane of higher plants. A salient feature of the model is that most of the pigments are located in the grana where photosystem I and II carry out linear electron transport, whereas the stroma lamellae, which harbour <20% of the pigments, carry out photosystem-I-mediated cyclic electron transport. This arrangement derives from the observation that more pigments are associated with photosystem I, which therefore captures more quanta than photosystem II. The excess pigments associated with photosystem I are thought to be located in the stroma lamellae.
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| 2. |
- Allen, John
(författare)
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Cyclic, pseudocyclic and noncyclic photophosphorylation: new links in the chain.
- 2003
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Ingår i: Trends in Plant Science. - 1360-1385. ; 8:1, s. 15-19
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthetic electron transport is coupled to ATP synthesis. This process – photosynthetic phosphorylation – proceeds by several alternative electron-transport pathways in isolated chloroplasts. The question: ‘Which of these works in real life?’ has long occupied students of photosynthesis. Recent results from structural biology and genomics suggest that the answer is ‘All of them’. The interplay between the pathways might explain the flexibility of photosynthesis in meeting different metabolic demands for ATP.
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| 3. |
- Allen, J.F., et al.
(författare)
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Molecular recognition in thylakoid structure and function
- 2001
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Ingår i: Trends in Plant Science. - 1360-1385. ; 6:7, s. 317-326
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Tidskriftsartikel (refereegranskat)abstract
- In photosynthesis, light-harvesting chlorophyll molecules are shunted between photosystems by phosphorylation of the protein to which they are bound, An anchor for the phosphorylated chlorophyll-protein complex has now been identified in the reaction centre of chloroplast photosystem I. This finding supports the idea that molecular recognition, not membrane surface charge, governs the architecture of the chloroplast thylakoid membrane. We describe a model for the chloroplast thylakoid membrane that is consistent with recent structural data that specify the relative dimensions of intrinsic protein complexes and their dispositions within the membrane. Control of molecular recognition accommodates membrane stacking, lateral heterogeneity and regulation of light-harvesting function by means of protein phosphorylation during state transitions - adaptations that compensate for selective excitation of photosystem I or photosystem II. High-resolution structural description of membrane protein-protein interactions is now required to understand thylakoid structure and regulation of photosynthesis.
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| 4. |
- Escobar, Matthew, et al.
(författare)
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Agrobacterium tumefaciens as an agent of disease
- 2003
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Ingår i: Trends in Plant Science. - 1360-1385. ; 8:8, s. 380-386
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Forskningsöversikt (refereegranskat)abstract
- Twenty-six years ago it was found that the common soil bacterium Agrobacterium tumefaciens is capable of extraordinary feats of interkingdom genetic transfer. Since this discovery, A. tumefaciens has served as a model system for the study of type IV bacterial secretory systems, horizontal gene transfer and bacterial-plant signal exchange. It has also been modified for controlled genetic transformation of plants, a core technology of plant molecular biology. These areas have often overshadowed its role as a serious, widespread phytopathogen - the primary driver of the first 80 years of Agrobacteriurn research. Now, the diverse areas of A. tumefaciens research are again converging because new discoveries in transformation biology and the use of A. tumefaciens vectors are allowing the development of novel, effective biotechnology-based strategies for the control of crown gall disease.
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| 5. |
- Kjellbom, Per, et al.
(författare)
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Aquaporins and water homeostasis in plants
- 1999
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Ingår i: Trends in Plant Science. - 1360-1385. ; 4:8, s. 308-314
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Forskningsöversikt (refereegranskat)abstract
- Aquaporins are water channel proteins of vacuolar and plasma membranes. When opened they facilitate the passive movement of water molecules down a water potential gradient. In Arabidopsis, 30 genes have been found that code for aquaporin homologues. Some of these genes code for highly abundant constitutively expressed proteins and some are known to be temporally and spatially regulated during development and in response to stress. The water transport activity of two aquaporins is regulated at the protein level by phosphorylation and dephosphorylation. At a given time, cells express several different aquaporins, and it is probable that vacuolar and plasma membrane aquaporins acting in concert are responsible for the cytosolic osmoregulation that is necessary for maintaining normal metabolic processes. Inhibition studies of aquaporins in vivo and antisense mutant studies suggest that, in addition to cytosolic osmoregulation, aquaporins are important for the bulk flow of water in plants.
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| 6. |
- Møller, Ian M., et al.
(författare)
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The role of NADP in the mitochondrial matrix
- 1998
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Ingår i: Trends in Plant Science. - 1360-1385. ; 3:1, s. 21-27
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Tidskriftsartikel (refereegranskat)abstract
- Many diverse metabolic processes are coupled to the turnover of the coenzyme NADP in the matrix of plant mitochondria. NADPH can be produced via the NADP-specific isocitrate dehydrogenase as well as via enzymes like NAD-malic enzyme, NAD-malate dehydrogenase and Δ1-pyrroline-5-carboxylate dehydrogenase. Although not NADP-specific, the latter enzymes can all catalyse the reduction of NADP+ at appreciable rates. The NADPH produced can be used in folate metabolism, by glutathione reductase for protection against oxidative damage, and by thioredoxin reductase in the (putative) regulation of metabolic pathways via thiol-group reduction. It can also be oxidized by the respiratory chain via a Ca2+-dependent NADPH dehydrogenase - this is a potential way of regulating the NADP reduction level in the matrix and thus, indirectly, the other processes. It is now possible to present an integrated picture of NADP turnover inside the mitochondrion.
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| 7. |
- Harrar, Y., et al.
(författare)
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FKBPs : at the crossroads of folding and transduction
- 2001
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385 .- 1878-4372. ; 6:9, s. 426-431
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Forskningsöversikt (refereegranskat)abstract
- FK506-binding proteins (FKBPs) belong to the large family of peptidyl-prolyl cis-trans isomerases, which are known to be involved in many cellular processes, such as cell signalling, protein trafficking and transcription. FKBPs associate into protein complexes, although the involvement and precise role of their foldase activity remain to be elucidated. FKBPs represent a large gene family in plants that is involved in growth and development. Disruption of genes encoding FKBPs in plants and animals has underlined the importance of this family of proteins in the regulation of cell division and differentiation.
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| 8. |
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| 9. |
- Sjöling, Sara, et al.
(författare)
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Mitochondrial targeting peptides in plants
- 1998
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Ingår i: Trends in Plant Science. - 1360-1385 .- 1878-4372. ; 3:4, s. 136-140
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Tidskriftsartikel (refereegranskat)abstract
- Proteins function at distinct sites in the cell, yet most are primarily synthesized in the cytosol and must therefore be transported intracellularly to their final destination. Mitochondrial targeting peptides are localized at the N-terminus of the precursor proteins and most are cleaved off after import into mitochondria. Cleavage is catalysed by the general mitochondrial processing peptidase, which, in plants, is integrated into the bc1 complex of the respiratory chain. This peptidase recognizes the cleavage sites of nearly 1000 precursor proteins that have no sequence similarity.
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| 10. |
- Allen, John
(författare)
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Cytochrome b(6)f: structure for signalling and vectorial metabolism
- 2004
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385. ; 9:3, s. 130-137
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Forskningsöversikt (refereegranskat)abstract
- Following decades of detailed kinetic and spectroscopic evidence, two new, independent X-ray structures for the cytochrome b(6)f complex of photosynthesis now reveal the arrangement of its key electron carriers relative to each other, and to their protein ligands. But these are not predictable additions to the structural collection. The complex is dimeric, and encloses a central chamber in which plastoquinone and its redox intermediates couple proton translocation with cytochrome oxidation and reduction. The structures also announce a fourth, wholly unexpected haem, that could be the long-sought, missing link of photosystem I cyclic photophosphorylation. One chlorophyll molecule and one carotenoid molecule add to the enigma of this dark, downhill electron transfer complex, linking the real photosystems I and II. Conserved structural features offer clues to the evolution of photosynthesis, and to the initiation of redox signals required for genome function.
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