Mechanism of photo-induced and antimycin A-induced carotenoid synthesis in mycobacterium marinum. Requirements for carotenogenesis and further evidence for protein synthesis following induction

At concentrations of 0.1 Lf (0.25 µg.)/ml., or greater, diphtheria toxin produces an immediate decrease (40 ± 5 per cent) in the steady-state level of incorporation of inorganic phosphate into ATP by cultures of normal human kidney cells growing at 37°C. in the presence of glucose. The effect is readily reversible by specific antitoxin for a period of 30 minutes or more after adding toxin. Protein synthesis in these cells continues at a normal rate for 60 minutes after adding toxin and the toxin-treated cells are able to take up and concentrate potassium ions normally for at least 1 hour. Even high concentrations of toxin (5 Lf/ml. or more) fail to effect either protein synthesis or ATP formation by cultures of spleen cells from the mouse, an animal that is relatively resistant to the lethal action of the toxin. Of various inhibitors studied, antimycin A most closely resembles toxin in its action, both on protein synthesis and on ATP formation. Mouse cells are considerably more resistant to antimycin A than are human kidney cells. Human kidney cells treated with saturating doses of toxin continue to form RNA at a normal rate for about 1 hour, after which the rates of both Pi32 incorporation and of 6-C14-orotic acid incorporation into RNA sharply decline and continue at about 40 to 50 per cent their initial rate. At 37°C., S35-methionine incorporation into cell protein ceases altogether 60 to 75 minutes after addition of a saturating dose of toxin. The effect of saturating doses of toxin on S35-methionine incorporation into human kidney cell protein at different temperatures, has been studied. It is concluded from the present studies that diphtheria toxin exerts a primary, reversible effect at the surface of susceptible cells where it inhibits cytochrome-linked phosphorylation concerned with transport of inorganic phosphate across the cell membrane.

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Bead rings at the endoplasmic reticulum-golgi complex boundary: morphological changes accompanying inihibition of intracellular transport of secretory proteins in arthropod fat body tissue

The Journal of Cell Biology ◽

10.1083/jcb.90.1.92 ◽

1981 ◽

Vol 90 (1) ◽

pp. 92-100 ◽

Cited By ~ 11

Author(s):

DA Brodie

Keyword(s):

Endoplasmic Reticulum ◽

Protein Synthesis ◽

Oxidative Phosphorylation ◽

Golgi Complex ◽

Intracellular Transport ◽

Ring Structure ◽

Prolonged Treatment ◽

Antimycin A ◽

Secretory Material ◽

Rough Er

Golgi complex beads are 10-nm particles arranged in rings on the smooth surface of rough endoplasmic reticulum (ER) makind the forming face of the Golgi complex (GC). In arthropod cells they stain specifically with bismuth. Their morphology has been studied after treatment with reagents known to interfere with GC function. Inhibitors of oxidative phosphorylation (antimycin A, cyanide, and anoxia), but not an inhibitor of glycolysis (iodoacetate), both cause the bead rings to collapse and the GC saccules to round up, and inhibit transition vesicle (TV) formation. Cycloheximide blocks protein synthesis on ribosomes but does not stop TV formation or disrupt bead rings, even after prolonged treatment (6 h) to allow emptying of the rough ER cisternae. Thus the collapse of bead rings is not attributable to inhibition of protein synthesis, and the ring structure of beads does not require continued protein synthesis and secretion for its maintenance. Valinomycin has effects on the GC similar to those of antimycin A, but A23187, monensin, and lasalocid do not affect bead ring structure or TV formation. These results are consistent with valinomycin's secondarily uncoupling mitochondria, which collapses bead rings and prevents TV formation. Thus inhibitors of oxidative phosphorylation do not influence the beads through cation movement. Because mononsin and lasalocid block secretion at the level of the condensing vacuoles, bead rings are not influenced by blocks in secretion distal to them or by the backup of secretory material. These experiments are consistent with inhibitors of oxidative phosphorylation collapsing bead rings by decreasing intracellular ATP. The concomitant block to TV formation and the collapse of bead rings suggests that integrity of the bead rings is essential for the transport of secretory material from the rough ER to the GC.

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Cytosolic translational responses differ under conditions of severe short-term and long-term mitochondrial stress

Molecular Biology of the Cell ◽

10.1091/mbc.e18-10-0628 ◽

2019 ◽

Vol 30 (15) ◽

pp. 1864-1877 ◽

Cited By ~ 6

Author(s):

Lukasz Samluk ◽

Malgorzata Urbanska ◽

Katarzyna Kisielewska ◽

Karthik Mohanraj ◽

Min-Ji Kim ◽

...

Keyword(s):

Protein Synthesis ◽

Genetic Alterations ◽

Prolonged Treatment ◽

Compensatory Mechanism ◽

Antimycin A ◽

Short Term ◽

Mitochondrial Stress ◽

Mtor Kinase ◽

Inhibition Of Protein Synthesis

Previous studies demonstrated that cells inhibit protein synthesis as a compensatory mechanism for mitochondrial dysfunction. Protein synthesis can be attenuated by 1) the inhibition of mTOR kinase, which results in a decrease in the phosphorylation of S6K1 and 4E-BP1 proteins, and 2) an increase in the phosphorylation of eIF2α protein. The present study investigated both of these pathways under conditions of short-term acute and long-term mitochondrial stress. Short-term responses were triggered in mammalian cells by treatment with menadione, antimycin A, or CCCP. Long-term mitochondrial stress was induced by prolonged treatment with menadione or rotenone and expression of genetic alterations, such as knocking down the MIA40 oxidoreductase or knocking out NDUFA11 protein. Short-term menadione, antimycin A, or CCCP cell treatment led to the inhibition of protein synthesis, accompanied by a decrease in mTOR kinase activity, an increase in the phosphorylation of eIF2α (Ser51), and an increase in the level of ATF4 transcription factor. Conversely, long-term stress led to a decrease in eIF2α (Ser51) phosphorylation and ATF4 expression and to an increase in S6K1 (Thr389) phosphorylation. Thus, under long-term mitochondrial stress, cells trigger long-lasting adaptive responses for protection against excessive inhibition of protein synthesis.

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Homochirality as the Signature of Extra-Terrestrial Life

International Astronomical Union Colloquium ◽

10.1017/s0252921100015037 ◽

1997 ◽

Vol 161 ◽

pp. 505-510

Author(s):

Alexandra J. MacDermott ◽

Laurence D. Barron ◽

Andrè Brack ◽

Thomas Buhse ◽

John R. Cronin ◽

...

Keyword(s):

Amino Acids ◽

Protein Synthesis ◽

Optical Rotation ◽

Physical Origin ◽

Natural Choice ◽

Rosetta Mission ◽

Terrestrial Life ◽

Subsurface Layers ◽

Solar System Bodies ◽

Origin Of Homochirality

AbstractThe most characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images. We therefore suggest that a search for extra-terrestrial life can be approached as a Search for Extra- Terrestrial Homochirality (SETH). The natural choice for a SETH instrument is optical rotation, and we describe a novel miniaturized space polarimeter, called the SETH Cigar, which could be used to detect optical rotation as the homochiral signature of life on other planets. Moving parts are avoided by replacing the normal rotating polarizer by multiple fixed polarizers at different angles as in the eye of the bee. We believe that homochirality may be found in the subsurface layers on Mars as a relic of extinct life, and on other solar system bodies as a sign of advanced pre-biotic chemistry. We discuss the chiral GC-MS planned for the Roland lander of the Rosetta mission to a comet and conclude with theories of the physical origin of homochirality.

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Lymphocyte activity and protein synthesis

Clinical Science ◽

10.1042/cs20010237 ◽

2001 ◽

Vol 101 (6) ◽

pp. 591

Author(s):

DEREK C. MACALLAN

Keyword(s):

Protein Synthesis ◽

Lymphocyte Activity

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