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Photosynthetic redox control of nuclear gene expression 总被引:9,自引:0,他引:9
Chloroplasts contain 3000-4000 different proteins but only a small subset of them is encoded in the plastid genome while the majority is encoded in the nucleus. Expression of these genes therefore requires a high degree of co-ordination between nucleus and chloroplast. This is achieved by a bilateral information exchange between both compartments including nucleus-to-plastid (anterograde) and plastid-to-nucleus (retrograde) signals. The latter represent a functional feedback control which couples the expression of nuclear encoded plastid proteins to the actual functional state of the organelle. The efficiency of photosynthesis is a very important parameter in this context since it is influenced by many environmental conditions and therefore represents a sensor for the residing environment. Components of the photosynthetic electron transport chain exhibit significant changes in their reduction/oxidation (redox) state depending on the photosynthetic electron flow and therefore serve as signalling parameters which report environmental influences on photosynthesis. Such redox signals control chloroplast and nuclear gene expression events and play an important role in the co-ordination of both genetic compartments. It is discussed here which photosynthetic parameters are known to control nuclear gene expression, how these signals are transduced toward the nucleus, and how they interact with other plastid retrograde signals and cytosolic light perception systems. 相似文献
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In vivo visualization of Mg-protoporphyrin IX, a coordinator of photosynthetic gene expression in the nucleus and the chloroplast 总被引:1,自引:0,他引:1
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The photosynthetic apparatus is composed of proteins encoded by genes from both the nucleus and the chloroplast. To ensure that the photosynthetic complexes are assembled stoichiometrically and to enable their rapid reorganization in response to a changing environment, the plastids emit signals that regulate nuclear gene expression to match the status of the plastids. One of the plastid signals, the chlorophyll intermediate Mg-ProtoporphyrinIX (Mg-ProtoIX) accumulates under stress conditions and acts as a negative regulator of photosynthetic gene expression. By taking advantage of the photoreactive property of tetrapyrroles, Mg-ProtoIX could be visualized in the cells using confocal laser scanning spectroscopy. Our results demonstrate that Mg-ProtoIX accumulated both in the chloroplast and in the cytosol during stress conditions. Thus, the signaling metabolite is exported from the chloroplast, transmitting the plastid signal to the cytosol. Our results from the Mg-ProtoIX over- and underaccumulating mutants copper response defect and genome uncoupled5, respectively, demonstrate that the expression of both nuclear- and plastid-encoded photosynthesis genes is regulated by the accumulation of Mg-ProtoIX. Thus, stress-induced accumulation of the signaling metabolite Mg-ProtoIX coordinates nuclear and plastidic photosynthetic gene expression. 相似文献
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Hassidim M Yakir E Fradkin D Hilman D Kron I Keren N Harir Y Yerushalmi S Green RM 《The Plant journal : for cell and molecular biology》2007,51(4):551-562
The Arabidopsis circadian system regulates the expression of up to 36% of the nuclear genome, including many genes that encode photosynthetic proteins. The expression of nuclear-encoded photosynthesis genes is also regulated by signals from the chloroplasts, a process known as retrograde signaling. We have identified CHLOROPLAST RNA BINDING (CRB), a putative RNA-binding protein, and have shown that it is important for the proper functioning of the chloroplast. crb plants are smaller and paler than wild-type plants, and have altered chloroplast morphology and photosynthetic performance. Surprisingly, mutations in CRB also affect the circadian system, altering the expression of both oscillator and output genes. In order to determine whether the changes in circadian gene expression are specific to mutations in the CRB gene, or are more generally caused by the malfunctioning of the chloroplast, we also examined the circadian system in mutations affecting STN7, GUN1, and GUN5, unrelated nuclear-encoded chloroplast proteins known to be involved in retrograde signaling. Our results provide evidence that the functional state of the chloroplast may be an important factor that affects the circadian system. 相似文献
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A structural phylogenetic map for chloroplast photosynthesis 总被引:2,自引:0,他引:2
Chloroplasts are cytoplasmic organelles and the sites of photosynthesis in eukaryotic cells. Advances in structural biology and comparative genomics allow us to identify individual components of the photosynthetic apparatus precisely with respect to the subcellular location of their genes. Here we present outline maps of four energy-transducing thylakoid membranes. The maps for land plants and red and green algae distinguish protein subunits encoded in the nucleus from those encoded in the chloroplast. We find no defining structural feature that is common to all chloroplast gene products. Instead, conserved patterns of gene location are consistent with photosynthetic redox chemistry exerting gene regulatory control over its own rate-limiting steps. Chloroplast DNA carries genes whose expression is placed under this control. 相似文献
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Why chloroplasts and mitochondria contain genomes 总被引:2,自引:0,他引:2
Allen JF 《Comparative and Functional Genomics》2003,4(1):31-36
Chloroplasts and mitochondria originated as bacterial symbionts. The larger, host
cells acquired genetic information from their prokaryotic guests by lateral gene
transfer. The prokaryotically-derived genes of the eukaryotic cell nucleus now
function to encode the great majority of chloroplast and mitochondrial proteins,
as well as many proteins of the nucleus and cytosol. Genes are copied and moved
between cellular compartments with relative ease, and there is no established obstacle
to successful import of any protein precursor from the cytosol. Yet chloroplasts and
mitochondria have not abdicated all genes and gene expression to the nucleus and
to cytosolic translation. What, then, do chloroplast- and mitochondrially-encoded
proteins have in common that confers a selective advantage on the cytoplasmic
location of their genes? The proposal advanced here is that co-location of chloroplast
and mitochondrial genes with their gene products is required for rapid and direct
regulatory coupling. Redox control of gene expression is suggested as the common
feature of those chloroplast and mitochondrial proteins that are encoded in situ.
Recent evidence is consistent with this hypothesis, and its underlying assumptions
and predictions are described. 相似文献
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