Mitochondrial and Cytoplasmic Polysomes from Neurospora crassa

Küntzel, Hans; Noll, Hans

doi:10.1038/2151340a0

Cited by 202 publications

(47 citation statements)

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“…In the best documented studies, the "ribosomal" RNA from Neurospora mitochondria has been shown to sediment like bacterial rRNA and more slowly than homologous cytoplasmic rRNA (5,6) . A similar situation appears to hold for yeast (4,(25)(26)(27) .…”

Section: Discussionmentioning

confidence: 99%

“…3) in hamster mitochondria ; (b) its base ratios THE JOURNAL OF CELL BIOLOGY . VOLUME 46, 1970 • pages 945-251 resembled those of mitochondrial ribosomal RNA from yeast (4) and Neurospora (5,6) ; and (c) it was separable into a major and a minor component on prolonged centrifugation or on acrylamide gel electrophoresis . However, the RNA appeared to be unusually small for ribosomal RNA .…”

Section: Introductionmentioning

confidence: 99%

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Mitochondrial Rna From Cultured Animal Cells

Montenecourt

Langsam

Dubin

1970

The Journal of Cell Biology

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Discrete RNA fractions sedimenting slightly slower than 18s ribosomal RNA have been found in mitochondrial preparations from both hamster (BHK-21) and mouse (L-929) cells . This RNA could be separated into two components, present in approximately equimolar amounts, by prolonged zonal centrifugation or acrylamide gel electrophoresis . The hamster components had sedimentation constants averaging 16 .8 and 13 .4, and molecular weights (estimated by gel electrophoresis) averaging 0.74 and 0.42 X 106 daltons . Mixed labeling experiments showed that the mouse components sedimented and electrophoresed 3-6% more slowly than the corresponding hamster components . The RNA from both cell lines resembled mitochondrial ribosomal RNA from yeast and Neurospora in being GC poor, and in addition the larger and smaller components resembled each other in base composition . These results, taken with those of other recent studies, are compatible with the idea that our high molecular weight mitochondrial RNA is ribosomal ; such RNA would then constitute a uniquely small size-class of ribosomal RNA .

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mitochondrial Rna From Cultured Animal Cells

Montenecourt

Langsam

Dubin

1970

The Journal of Cell Biology

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“…However, the different electrophoretic behaviors of Neurospora mitochondrial rRNA in standard Na buffer and Mg buffer which are shown in Fig.3, cannot be expleined solely on this basis, especially since Neurospora mitochondrial rRNA shows the highest G + C content among the three mitochondrial samples tested. It should be noted that Neurospora mitochondrial rRNA also shows some variation in its sedimentation velocity relative to E. coli rRNA in Mg and Na buffers [26]. Likewise, variations were reported [20] in the s20, of this mitochondrial rRNA relative to that of its homologous cytoplasmic rRNA in buffer of high (0.5M) and moderate (0.1 M) salt.…”

Section: Discussionmentioning

confidence: 99%

“…This is reflected, to an extent, in their different physical behaviors as well. For example, Neurospora mitochondrial rRNA, which has the highest G + C content (380/,, see [26]) among the mitochondrial rRNAs studied, shows higher Tm and ' J/ , H values a t 280 nm (cf., Table 1) and a faster sedimentation velocity in sucrose (cf., Fig.4) than the other mitochondrial rRNAs. I n general, the unique physico-chemical characteristics found for Aspergillus mitochondrial rRNA [l --51 appear to be characteristic of other fungal mitochondrial rRNAs.…”

Section: Discussionmentioning

confidence: 99%

Physico‐Chemical Properties of Mitochondrial Ribosomal RNA from Fungi

Edelman

Verma

Herzog

et al. 1971

European Journal of Biochemistry

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Several physico-chemical properties of mitochondrial and cytoplasmic ribosomal RNA from the filamentous fungi, Trichoderma viricle and Neurospora crassa were determined and compared with those for Aspergillus nidulans.1. The thermal denaturation patterns of the mitochondrial rRNAs differed markedly from those of their homologous cytoplasmic rRNAs. The two rRNAs, therefore, possess distinct conformations in solution. 2.The guanine + cytosine content of Trichoderma mitochondrial rRNA was shown to be very low (31.5 and 35.5O/, for the heavy and light components) and to differ considerably from that of its cytoplasmic rRNA (50 and 49 ,Io). Such nucleotide compositions are characteristic of fungal mitochondrial rRNA and account, at least in part, for the unusual physical characteristics which these polynucleotides exhibit.3. Polyacrylamide gel electrophoresis of mitochondrial and cytoplasmic rRNA was performed in buffers of different ionic strenghts. I n low-salt buffer, the relative mobilities of the mitochondrial rRNAs were severely retarded, causing mitochondrial rRNA to migrate more slowly than cytoplasmic rRNA. I n Mg buffer, mitochondrial and cytoplasmic rRNA co-electrophoresed and were easily distinguished from Escherichia coli rRNA. Thus, under certain conditions, the conformational peculiarities of fungal mitochondrial rRNAs are expressed with this technique as well. It is concluded that accurate extrapolations from electrophoretic mobilities to molecular weight values cannot be made for these rRNA samples.4. Mitochondrial rRNAs sediment more slowly than their corresponding cytoplasmic rRNAs. However, under the same experimental conditions the sedimentation velocity patterns for the various mitochondrial rRNAs are not identical.5. While the above measurements clearly distinguish mitochondrial rRNAs, as a group, from cytoplasmic and bacterial rRNAs, they also point out a considerable physical heterogeneity among the fungal mitochondrial rRNAs.I n previous reports we have described several physical and chemical characteristics of mitochondrial ribosomal RNA from the fungus, Aspergillus nidulans. Observations relating to size, conformation, nucleot,ide coniposition and nucleotide distribution have revealed that mitochondrial rRNA in this fungus differs markedly not only from its homologous cytoplasmic rRNA but from bacterial-type rRNA as well [i -61. In the present report we extend some of these observations to two other filamentous fungi, Trichoderrna viride and Neurospora crassa. In particular, thermally-induced absorbance changes and electrophoretic mobilities on polyacrylamide gels in buffers of different ionic strengths point out the conformational peculiarities of mitochondrial rRNA. These behaviors appear to be linked to the unusually low mole percentage of guanine and cytosine which the fungal mitochondrial rRNAs possess. While the physicochemical measurements serve to clearly distinguish fungal mitochondrial rRNA, as a group, from cytoplasmic and bacterial rRNAs, they also reveal differences among the ...

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“…Until now all preparations of mitochondrial polysomes have been obtained from organelles lysed by detergents . The polysomes are collected directly as a rapidly sedimenting fraction in analytical sucrose gradients (6)(7)(8)(9) or as a pellet sedimenting through high molarity sucrose in a step gradient (8) . In applying these methods to poky mitochondria and analyzing the subunit content of the polysome preparations after incubation with puromycin, we found that mass ratios of large to small ribosomal subunits were not 2 :1 but were close to 10 :1 .…”

Section: Introductionmentioning

confidence: 99%