Action of Intracellular Proteinases on Mitochondrial Translation Products of<i>Neurospora crassa</i>and<i>Schizosaccharomyces pombe</i>

Michel, Rainer; Liebl, Anton; Hartmann, Anton; Neupert, Walter

doi:10.1515/bchm2.1976.357.1.415

Cited by 18 publications

(10 citation statements)

References 7 publications

(6 reference statements)

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“…Purity was assessed by enzyme-marker studies and by a rationale of macromolecule labeling used in the purification of synaptic vesicles (6) of mammals. Osmotically induced density changes were shown to be the cause of the source of variation in density (1.06 to 1.35 g/cm3) reported by previous workers (16,17,19,21) for the N. crassa vacuole.(This paper is drawn from a dissertation by L.E.V. in partial fulfillment of the requirements for the Ph.D. in Biological Sciences, University of California, Irvine, 1980.)…”

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confidence: 73%

“…The identity of isolated N. crassa vacuoles has been unclear, owing to the variety ofmarkers studied by various workers and the different particle densities reported (16,17,19,21,35 , unpublished data). Given the high density of the contents, isopycnic equilibrium is never reached during centrifugation in a sucrose gradient.…”

Section: Discussionmentioning

confidence: 99%

“…The organelle, called the "vesicle," was more dense than mitochondria (35) and invited comparison with the dense protease-containing particle, later called the vacuole (21), of Matile and co-workers (19). Because Weiss did not detect appreciable protease activity in his early work, and because the vacuole of N. crassa was characterized in certain conditions as a rather light organelle by other workers (17), the identity of the N. crassa vacuole remained open.…”

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Purification of vacuoles from Neurospora crassa.

Vaughn

Davis

1981

Mol. Cell. Biol.

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The Neurospora crassa vacuole, defined by its content of basic amino acids, polyphosphate, protease, phosphatases, and a-mannosidase, was purified to near homogeneity. The procedure depends upon homogenization of snail gut enzymedigested cells in a buffer osmotically stabilized with 1 M sorbitol, differential centrifugation of the extract, and sucrose density gradient centrifugation of the organellar pellet. Isopycnic centrifugation of vacuoles in 2.25 M sorbitol-Metrizamide density gradients yielded a peak (density, 1.31 g/cm3) of vacuolar markers coincident with 'P-phospholipids, trichloroacetate-insoluble '4C, and trichloroacetate-soluble "4C. A trail of macromolecular markers in the lighter portions of the gradient reflected, at least in part, heterogeneity of the vacuoles. Almost no contamination by mitochondria or glyoxysomes was detected. Vacuoles were very heterogeneous in size as estimated by velocity sedimentation, but most were larger than mitochondria. Variations of the osmotic strength of the medium were found to alter the equilibrium density of vacuole preparations from 1.06 g/cm3 to over 1.3 g/cm3. This explains the great variation in density reported previously for the "vacuole," the "vesicle," and the "protease particle" of N. crassa, all of which appear to be the same entity.In 1973, Weiss (35) and Subramanian et al. (28) reported the existence of an organelle in Neurospora crassa which sequestered basic amino acids. The organelle, called the "vesicle," was more dense than mitochondria (35) and invited comparison with the dense protease-containing particle, later called the vacuole (21), of Matile and co-workers (19). Because Weiss did not detect appreciable protease activity in his early work, and because the vacuole of N. crassa was characterized in certain conditions as a rather light organelle by other workers (17), the identity of the N. crassa vacuole remained open. In the meantime, Wiemken and his co-workers purified vacuoles from yeasts (11,38). Although yeast vacuoles are of low density and quite large, they contain most of the cellular basic amino acids, polyphosphates, proteases, a-mannosidase, and other hydrolytic enzymes (39). Recently, we showed (9) that the basic amino acids are located in the same dense organelle as the polyphosphates of N. crassa. We report here the purification of the N. crassa vacuole, defined by its amino acid and polyphosphate content, and its association with protease, a-mannosidase, and certain other enzyme activities. Purity was assessed by enzyme-marker studies and by a rationale of macromolecule labeling used in the purification of synaptic vesicles (6) of mammals. Osmotically induced density changes were shown to be the cause of the source of variation in density (1.06 to 1.35 g/cm3) reported by previous workers (16,17,19,21) for the N. crassa vacuole.(This paper is drawn from a dissertation by L.E.V. in partial fulfillment of the requirements for the Ph.D. in Biological Sciences, University of California, Irvine, 1980.) MATERIALS AND METHODSStr...

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confidence: 73%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Purification of vacuoles from Neurospora crassa.

Vaughn

Davis

1981

Mol. Cell. Biol.

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“…The question arises whether the observed breakdown of mitochondrial translation products could be due to contaminating cytoplasmic proteinases. Vesicles containing proteinases capable of rapidly hydrolysing mitochondrial translation products were detected by Michel et al (1976) in mitochondrial preparations from Neurospora crassa. These proteinases were activated by Triton X-100.…”

Section: Resultsmentioning

confidence: 99%

Proteolysis of the products of mitochondrial protein synthesis in yeast mitochondria and submitochondrial particles

Kalnov¹,

Novikova²,

Zubatov³

et al. 1979

Biochemical Journal

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Degradation of mitochondrial translation products in Saccharomyces cerevisiae mitochondria was studied by selectively labelling these entities in vivo in the presence of cycloheximide and following their fate in isolated mitochondria. One-third to one-half of the mitochondrial translation products are shown to be degraded, depending on the culture growth phase, with an approximate half-life of 35 min. This process is shown to be ATP-dependent, enhanced in the presence of puromycin and inhibited by chloramphenicol. Further, the proteolysis is suppressed by detergents and is insensitive to antisera against yeast proteinases A and B when measured in mitochondria or 'inside-out' submitochondrial particles. It is concluded that the breakdown of mitochondrial translation products is most probably due to the action of endogenous proteinase(s) associated with the mitochondrial inner membrane. This proteinase is inhibited by phenylmethanesulphonyl fluoride, leupeptin, antipain and chymostatin.

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“…Methods for removing cell wall fragments and for separating mitochondria and vacuoles with little cross-contamination are reported. The latter is important, as noted by previous workers (5), if protease-free preparations of mitochondria are to be obtained. Further, Neurospora vacuoles, which are rather fragile, have only recently been isolated in a pure state (2); the new method of isolation will facilitate further intensive study.…”

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confidence: 79%