Events Surrounding the Early Development of <i>Euglena</i> Chloroplasts

Egan, James M.; Dorsky, David; Schiff, Jerome A.

doi:10.1104/pp.56.2.318

Cited by 50 publications

(27 citation statements)

References 21 publications

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“…4). The LEV-induced rates of paramylum breakdown are the same during the first 12 hr of treatment in the light or the dark. After this time, cells treated with LEV in the light degrade paramylum faster than cells treated with LEV in the dark.…”

Section: Resultsmentioning

confidence: 62%

“…In Euglena, a nonchloroplast, blue-absorbing photoreceptor controls cytoplasmic ribosomal RNA synthesis (5,36), carotenoid synthesis (8), the synthesis of a number of proteins (27), and the events required for the elimination of the lag period in Chl synthesis (12,17). Cell division (7,20), and protein synthesis and turnover (15,28) are also regulated by a nonchloroplast photoreceptor.…”

Section: Discussionmentioning

confidence: 99%

“…The control of these compartments seems to involve separate photoreceptors, the plastid compartment being regulated by a red-blue photoreceptor similar or identical to PChl(ide) (13) whereas the nonchloroplast compartment(s) are regulated by a photoreceptor absorbing mainly in the blue region of the spectrum (12,27). Among the processes which have been shown to be under light control and required in the nonchloroplast portion of the cell is the aerobic metabolism of paramylum which is necessary to supply energy and carbon for plastid development (9,10,14,19,25).…”

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confidence: 99%

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Events Surrounding the Early Development of Euglena Chloroplasts

Schwartzbach¹,

Schiff²,

Goldstein³

1975

Plant Physiol.

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Section: Resultsmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Events Surrounding the Early Development of Euglena Chloroplasts

Schwartzbach¹,

Schiff²,

Goldstein³

1975

Plant Physiol.

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“…One of these, a red-blue receptor which may be identical with Pchl(ide) appears to be present in the chloroplast and seems to control the synthesis of proteins on both chloroplast and cytoplasmic ribosomes (6,24). Although the increase in the levels of a large number of chloroplast localized polypeptides and the decrease in the levels of a large number of mitochondrial polypeptides is independent of Chl synthesis or chloroplast protein synthesis (18), the bleached mutant W3BUL has lost the ability to photoregulate the levels of many, but not all, proteins (15) which are found in the chloroplast, cytoplasm, and mitochondria.…”

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confidence: 99%

“…The blue absorbing nonchloroplast photoreceptor is also present in bleached mutants (3,12,20,(24)(25)(26). Events specifically required for chloroplast development, such as cytoplasmic rRNA synthesis (3), the synthesis of proteins required for rapid Chl synthesis (6), and the mobilization and aerobic metabolism of storage carbohydrates (25), appear to be controlled by the blue photoreceptor. Like Chl synthesis, all of the light dependent changes in polypeptide levels detected by two dimensional gel electrophoresis are catabolite sensitive; they are inhibited when cells are provided with specific carbon sources (16).…”

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Photocontrol of Chloroplast and Mitochondrial Polypeptide Levels in Euglena

Monroy

Gómez-Silva²,

Schwartzbach³

et al. 1986

Plant Physiol.

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Two dimensional polyacrylme gel electrophoresis resolved protein from intact chkroplasts of wild type Eugkxagrailis Klebs var. bacillaris Cori into 185 polypeptides of which 55 were lli on the whole cell polypeptide map. Of these chloroplast polypeptides, the relative amounts of 49 inased, the relative amounts of two decreased, and the relative amounts of four polypeptides were unaltered by exposure of dark grown resting cells to Light for 72 hours. Proteins from intact purified mitochondria obtined from a bleached mutant (W,.BSmL) lacking plastids were resolved into 193 polypeptides of which 44 were lalized on the whole cell polypeptide map from wild type cells. Of these mitochondrial polypeptides, the relative amount of one increased, the relative amounts of 12 were unaltered, and the relative amounts of 31 decreased after exposure of the dark grown rest cells to light. Since it is known that the development of the choroplast in Eagkxa occurs without a net increase in total cellular protein and without a chae in the size of the cellular amino acid pools, the degradation of mitochondrial polypeptides represents a major source of amino acids for the synthesis of chloroplast polypeptides.Light acting through a blue absorbing nonchloroplast photoreceptor, a red absorbing nonchloroplast photoreceptor, and a blue-red absorbing chloroplast photoreceptor which may be Pchl(ide) controls the polypeptide con;position of Euglena (24). mitochondrial Cyt (23). Based on electron microscopic (13,22,23) and autoradiographic studies (23), mitochondrial structure and proteins appear to be degraded during chloroplast development.In nondividing carbon starved resting cells, the carbon skeletons and energy required for chloroplast development are obtained through the degradation of preexisting molecules. Light promotes the degradation of the storage carbohydrate paramylum (25) and the degradation of RNA (3). Chloroplast proteins are synthesized in the absence of a net increase in total cellular proteins (23,24). Since the size of the amino acid pools remains constant during chloroplast development (23), the amino acids used for the synthesis of chloroplast proteins must be derived through the degradation of preexisting proteins. In photosynthetic cells, the chloroplast can provide most of the ATP, fatty acids, storage carbohydrates, and carbon skeletons required for growth. Enzymes required for the synthesis of these compounds during organotrophic growth are at least partially gratuitous during phototrophic growth and they are likely to be degraded to provide the amino acids for the synthesis of chloroplast proteins.Although it is clear that light selectively alters the polypeptide composition of the cell, the extent to which these alterations are localized in specific cellular compartments remains unclear. Studies of changes in the specific activity of individual enzymes are time consuming and they provide information regarding only a single enzyme whose regulation may not be charcteristic of the regulation of the majority...

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Photo and Nutritional Regulation of Euglena Organelle Development

Schwartzbach

2017

Advances in Experimental Medicine and Biology

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Euglena can use light and CO, photosynthesis, as well as a large variety of organic molecules as the sole source of carbon and energy for growth. Light induces the enzymes, in this case an entire organelle, the chloroplast, that is required to use CO as the sole source of carbon and energy for growth. Ethanol, but not malate, inhibits the photoinduction of chloroplast enzymes and induces the synthesis of the glyoxylate cycle enzymes that comprise the unique metabolic pathway leading to two carbon, ethanol and acetate, assimilation. In resting, carbon starved cells, light mobilizes the degradation of the storage carbohydrate paramylum and transiently induces the mitochondrial proteins required for the aerobic metabolism of paramylum to provide the carbon and energy required for chloroplast development. Other mitochondrial proteins are degraded upon light exposure providing the amino acids required for the synthesis of light induced proteins. Changes in protein levels are due to increased and decreased rates of synthesis rather than changes in degradation rates. Changes in protein synthesis rates occur in the absence of a concomitant increase in the levels of mRNAs encoding these proteins indicative of photo and metabolic control at the translational rather than the transcriptional level. The fraction of mRNA encoding a light induced protein such as the light harvesting chlorophyll a/b binding protein of photosystem II, (LHCPII) associated with polysomes in the dark is similar to the fraction associated with polysomes in the light indicative of photoregulation at the level of translational elongation. Ethanol, a carbon source whose assimilation requires carbon source specific enzymes, the glyoxylate cycle enzymes, represses the synthesis of chloroplast enzymes uniquely required to use light and CO as the sole source of carbon and energy for growth. The catabolite sensitivity of chloroplast development provides a mechanism to prioritize carbon source utilization. Euglena uses all of its resources to develop the metabolic capacity to utilize carbon sources such as ethanol which are rarely in the environment and delays until the rare carbon source is no longer available forming the chloroplast which is required to utilize the ubiquitous carbon source, light and CO.

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Events Surrounding the Early Development of Euglena Chloroplasts

Cited by 50 publications

References 21 publications

Events Surrounding the Early Development of Euglena Chloroplasts

Events Surrounding the Early Development of Euglena Chloroplasts

Photocontrol of Chloroplast and Mitochondrial Polypeptide Levels in Euglena

Photo and Nutritional Regulation of Euglena Organelle Development

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