Post-transcriptional regulation by light of the biosynthesis ofEuglena ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit

Keller, Mario; Chan, Raquel L.; Tessier, Luc-Henri; Weil, Jacques-Henry; Imbault, P.

doi:10.1007/bf00036807

Cited by 34 publications

(23 citation statements)

References 33 publications

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“…Other light-regulated plant proteins displaying this behavior are usually enzymes involved in basic metabolic activities, such as nitrate reductase (Naussaume et al, 1995), the small subunit of Rubisco (Keller et al, 1991), and starch phosphorylase (St. Pierre et al, 1996). This report suggests that these mechanisms may regulate alkaloid biosynthesis for an undetermined but important reason.…”

Section: A Photoreversible Phytochrome Is Involved In the Activation mentioning

confidence: 99%

Developmental and Light Regulation of Desacetoxyvindoline 4-Hydroxylase in Catharanthus roseus (L.) G. Don.1

Vázquez‐Flota

Luca

1998

Plant Physiology

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The expression of desacetoxyvindoline 4-hydroxylase (D4H), which catalyzes the second to the last reaction in vindoline biosynthesis in Catharanthus roseus, appears to be under complex, multilevel developmental and light regulation. Developmental studies with etiolated and light-treated seedlings suggested that although light had variable effects on the levels of d4h transcripts, those of D4H protein and enzyme activity could be increased, depending on seedling development, up to 9-and 8-fold, respectively, compared with etiolated seedlings. However, light treatment of etiolated seedlings could stop and reverse the decline of d4h transcripts at later stages of seedling development. Repeated exposure of seedlings to light was also required to maintain the full spectrum of enzyme activity observed during seedling development. Further studies showed that a photoreversible phytochrome appeared to be involved in the activation of D4H, since red-light treatment of etiolated seedlings increased the detectable levels of d4h transcripts, D4H protein, and D4H enzyme activity, whereas far-red-light treatment completely reversed this process. Additional studies also confirmed that different major isoforms of D4H protein exist in etiolated (isoelectric point, 4.7) and light-grown (isoelectric point, 4.6) seedlings, suggesting that a component of the light-mediated activation of D4H may involve an undetermined posttranslational modification. The biological reasons for this complex control of vindoline biosynthesis may be related to the need to produce structures that could sequester away from cellular activities the cytotoxic vinblastine and vincristine dimers that are derived partially from vindoline.

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Section: A Photoreversible Phytochrome Is Involved In the Activation mentioning

confidence: 99%

Developmental and Light Regulation of Desacetoxyvindoline 4-Hydroxylase in Catharanthus roseus (L.) G. Don.1

Vázquez‐Flota

Luca

1998

Plant Physiology

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“…The half-time for pSSU to SSU conversion is 4 2 min (Keller et al, 1991), compared with 20 min for the pLHCPll (Rikin and Schwartzbach, 1988). Dueto the faster rate of the pSSU transport to the chloroplast and processing to the SSU, steady state levels of Golgi pSSU are probably below the detection limits of immunomicroscopy.…”

Section: Are All Euglena Chloroplast Proteins Transported To the Er Amentioning

confidence: 99%

A soluble protein is imported into Euglena chloroplasts as a membrane-bound precursor.

Sulli

Schwartzbach

1996

Plant Cell

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The Euglena precursor to the small subunit of ribulose-1,Bbisphosphate carboxylase/oxygenase (pSSU) is a polyprotein. To determine the transport route from cytoplasm to chloroplast, Euglena was pulse labeled with 35S-sulfate and the organelles were separated on sucrose gradients. After a pulse, pSSU was found in the endoplasmic reticulum (ER) and Golgi apparatus. During a chase, ER-and Golgi-localized pSSU decreased concomitant with the appearance of SSU in chloroplasts. SSU was not found in pSSU-containing ER and Golgi fractions. Na2C03 did not remove pSSU from ER or Golgi membranes, indicating that it was an integral membrane protein. pSSU was inserted in vitro into canine microsomes, and Na2C03 did not remove pSSU from the microsomal membrane. The in vivo and in vitro experiments show that Euglena pSSU is inserted into the ER membrane and transported as an integral membrane protein to the Golgi apparatus before chloroplast import and polyprotein processing.

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“…RUBISCO enzyme activity increases after a 12 h lag period upon light exposure (Bovarnick et al 1974a, b;Freyssinet et al 1984a;HovenkampObbema and Stegwee 1974;Laval-Martin et al 1981;Neumann and Parthier 1973;Pineau 1982) and the lag period can be eliminated by preillumination (Freyssinet et al 1984a;Schimpf et al 1982). The increase in enzyme activity is due to an increase in the amount of the large and the small subunit (Freyssinet et al 1984a;Keller et al 1991;Monroy and Schwartzbach 1983;Pineau 1982). Induction is light dependent (Freyssinet et al 1984a;Pineau 1982).…”

Section: Photocontrol Of Chloroplast Developmentmentioning

confidence: 92%

“…Induction is light dependent (Freyssinet et al 1984a;Pineau 1982). Pulse labeling has shown that the increase in RUBISCO protein levels is due to an increase in the rates of large and small subunit synthesis (Keller et al 1991;Monroy et al 1987).…”

Section: Photocontrol Of Chloroplast Developmentmentioning

confidence: 99%

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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Post-transcriptional regulation by light of the biosynthesis ofEuglena ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit

Cited by 34 publications

References 33 publications

Developmental and Light Regulation of Desacetoxyvindoline 4-Hydroxylase in Catharanthus roseus (L.) G. Don.1

Developmental and Light Regulation of Desacetoxyvindoline 4-Hydroxylase in Catharanthus roseus (L.) G. Don.1

A soluble protein is imported into Euglena chloroplasts as a membrane-bound precursor.

Photo and Nutritional Regulation of Euglena Organelle Development

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