scholarly journals Yeast cells lacking 5'-->3' exoribonuclease 1 contain mRNA species that are poly(A) deficient and partially lack the 5' cap structure.

1993 ◽  
Vol 13 (8) ◽  
pp. 4826-4835 ◽  
Author(s):  
C L Hsu ◽  
A Stevens

Analysis of the slowed turnover rates of several specific mRNA species and the higher cellular levels of some of these mRNAs in Saccharomyces cerevisiae lacking 5'-->3' exoribonuclease 1 (xrn1 cells) has led to the finding that these yeast contain higher amounts of essentially full-length mRNAs that do not bind to oligo(dT)-cellulose. On the other hand, the length of mRNA poly(A) chains found after pulse-labeling of cells lacking the exoribonuclease, the cellular rate of synthesis of oligo(dT)-bound mRNA, and the initial rate of its deadenylation appeared quite similar to the same measurements in wild-type yeast cells. Examination of the 5' cap structure status of the poly(A)-deficient mRNAs by comparative analysis of the m7G content of poly(A)- and poly(A)+ RNA fractions of wild-type and xrn1 cells suggested that the xrn1 poly(A)- mRNA fraction is low in cap structure content. Further analysis of the 5' termini by measurements of the rate of 5'-->3' exoribonuclease 1 hydrolysis of specific full-length mRNA species showed that approximately 50% of the xrn1 poly(A)-deficient mRNA species lack the cap structure. Primer extension analysis of the 5' terminus of ribosomal protein 51A (RP51A) mRNA showed that about 30% of the poly(A)-deficient molecules of the xrn1 cells are slightly shorter at the 5' end. The finding of some accumulation of poly(A)-deficient mRNA species partially lacking the cap structure together with the reduction of the rate of mRNA turnover in cells lacking the enzyme suggest a possible role for 5'-->3' exoribonuclease 1 in the mRNA turnover process.

1993 ◽  
Vol 13 (8) ◽  
pp. 4826-4835
Author(s):  
C L Hsu ◽  
A Stevens

Analysis of the slowed turnover rates of several specific mRNA species and the higher cellular levels of some of these mRNAs in Saccharomyces cerevisiae lacking 5'-->3' exoribonuclease 1 (xrn1 cells) has led to the finding that these yeast contain higher amounts of essentially full-length mRNAs that do not bind to oligo(dT)-cellulose. On the other hand, the length of mRNA poly(A) chains found after pulse-labeling of cells lacking the exoribonuclease, the cellular rate of synthesis of oligo(dT)-bound mRNA, and the initial rate of its deadenylation appeared quite similar to the same measurements in wild-type yeast cells. Examination of the 5' cap structure status of the poly(A)-deficient mRNAs by comparative analysis of the m7G content of poly(A)- and poly(A)+ RNA fractions of wild-type and xrn1 cells suggested that the xrn1 poly(A)- mRNA fraction is low in cap structure content. Further analysis of the 5' termini by measurements of the rate of 5'-->3' exoribonuclease 1 hydrolysis of specific full-length mRNA species showed that approximately 50% of the xrn1 poly(A)-deficient mRNA species lack the cap structure. Primer extension analysis of the 5' terminus of ribosomal protein 51A (RP51A) mRNA showed that about 30% of the poly(A)-deficient molecules of the xrn1 cells are slightly shorter at the 5' end. The finding of some accumulation of poly(A)-deficient mRNA species partially lacking the cap structure together with the reduction of the rate of mRNA turnover in cells lacking the enzyme suggest a possible role for 5'-->3' exoribonuclease 1 in the mRNA turnover process.


1978 ◽  
Vol 119 (2) ◽  
pp. 213-235 ◽  
Author(s):  
Godeleine Fonty ◽  
Regina Goursot ◽  
David Wilkie ◽  
Giorgio Bernardi

1978 ◽  
Vol 24 (6) ◽  
pp. 637-642 ◽  
Author(s):  
K. C. Thomas ◽  
Mary Spencer

Effects of the carbon source and oxygen on ethylene production by the yeast Saccharomyces cerevisiae have been studied. The amounts of ethylene evolved by the yeast culture were less than those detected in the blank (an equal volume of uninoculated medium), suggesting a net absorption of ethylene by the yeast cells. Addition of glucose to the lactate-grown yeast culture induced ethylene production. This glucose-induced stimulation of ethylene production was inhibited to a great extent by cycloheximide. Results suggested that the yeast cells in the presence of glucose synthesized an ethylene precursor and passed it into the medium. The conversion of this precursor to ethylene might be stimulated by oxygen. The fact that ethylene was produced by the yeast growing anaerobically and also by respiration-deficient mutants isolated from the wild-type yeast suggested that mitochondrial ATP synthesis was not an absolute requirement for ethylene biogenesis.


1972 ◽  
Vol 65 (2) ◽  
pp. 207-212 ◽  
Author(s):  
Stanslav D. Ehrlich ◽  
Jean-Paul Thiery ◽  
Giorgio Bernardi

1999 ◽  
Vol 10 (11) ◽  
pp. 3943-3957 ◽  
Author(s):  
Alan L. Munn ◽  
Antje Heese-Peck ◽  
Brian J. Stevenson ◽  
Harald Pichler ◽  
Howard Riezman

Sterols are major components of the plasma membrane, but their functions in this membrane are not well understood. We isolated a mutant defective in the internalization step of endocytosis in a gene (ERG2) encoding a C-8 sterol isomerase that acts in the late part of the ergosterol biosynthetic pathway. In the absence of Erg2p, yeast cells accumulate sterols structurally different from ergosterol, which is the major sterol in wild-type yeast. To investigate the structural requirements of ergosterol for endocytosis in more detail, several erg mutants (erg2Δ, erg6Δ, anderg2Δerg6Δ) were made. Analysis of fluid phase and receptor-mediated endocytosis indicates that changes in the sterol composition lead to a defect in the internalization step. Vesicle formation and fusion along the secretory pathway were not strongly affected in the ergΔ mutants. The severity of the endocytic defect correlates with changes in sterol structure and with the abundance of specific sterols in the ergΔ mutants. Desaturation of the B ring of the sterol molecules is important for the internalization step. A single desaturation at C-8,9 was not sufficient to support internalization at 37°C whereas two double bonds, either at C-5,6 and C-7,8 or at C-5,6 and C-8,9, allowed internalization.


2019 ◽  
Vol 20 (16) ◽  
pp. 4023 ◽  
Author(s):  
Justyna P. Wróblewska ◽  
Ida J. van der Klei

There is an ongoing debate on how peroxisomes form: by growth and fission of pre-existing peroxisomes or de novo from another membrane. It has been proposed that, in wild type yeast cells, peroxisome fission and careful segregation of the organelles over mother cells and buds is essential for organelle maintenance. Using live cell imaging we observed that cells of the yeast Hansenula polymorpha, lacking the peroxisome fission protein Pex11, still show peroxisome fission and inheritance. Also, in cells of mutants without the peroxisome inheritance protein Inp2 peroxisome segregation can still occur. In contrast, peroxisome fission and inheritance were not observed in cells of a pex11 inp2 double deletion strain. In buds of cells of this double mutant, new organelles likely appear de novo. Growth of pex11 inp2 cells on methanol, a growth substrate that requires functional peroxisomes, is retarded relative to the wild type control. Based on these observations we conclude that in H. polymorpha de novo peroxisome formation is a rescue mechanism, which is less efficient than organelle fission and inheritance to maintain functional peroxisomes.


1990 ◽  
Vol 110 (1) ◽  
pp. 105-114 ◽  
Author(s):  
B K Haarer ◽  
S H Lillie ◽  
A E Adams ◽  
V Magdolen ◽  
W Bandlow ◽  
...  

We have isolated profilin from yeast (Saccharomyces cerevisiae) and have microsequenced a portion of the protein to confirm its identity; the region microsequenced agrees with the predicted amino acid sequence from a profilin gene recently isolated from S. cerevisiae (Magdolen, V., U. Oechsner, G. Müller, and W. Bandlow. 1988. Mol. Cell. Biol. 8:5108-5115). Yeast profilin resembles profilins from other organisms in molecular mass and in the ability to bind to polyproline, retard the rate of actin polymerization, and inhibit hydrolysis of ATP by monomeric actin. Using strains that carry disruptions or deletions of the profilin gene, we have found that, under appropriate conditions, cells can survive without detectable profilin. Such cells grow slowly, are temperature sensitive, lose the normal ellipsoidal shape of yeast cells, often become multinucleate, and generally grow much larger than wild-type cells. In addition, these cells exhibit delocalized deposition of cell wall chitin and have dramatically altered actin distributions.


1972 ◽  
Vol 65 (2) ◽  
pp. 173-189 ◽  
Author(s):  
Giorgio Bernardi ◽  
Gianni Piperno ◽  
Godeleine Fonty

1977 ◽  
Vol 110 (1) ◽  
pp. 17-47 ◽  
Author(s):  
Ariel Prunell ◽  
Helena Kopecka ◽  
François Strauss ◽  
Giorgio Bernardi

1986 ◽  
Vol 6 (2) ◽  
pp. 488-493
Author(s):  
T M Rickey ◽  
A S Lewin

We isolated the gene for citrate synthase (citrate oxaloacetate lyase; EC 4.1.3.7) from Saccharomyces cerevisiae and ablated it by inserting the yeast LEU2 gene within its reading frame. This revealed a second, nonmitochondrial citrate synthase. Like the mitochondrial enzyme, this enzyme was sensitive to glucose repression. It did not react with antibodies against mitochondrial citrate synthase. Haploid cells lacking a gene for mitochondrial citrate synthase grew somewhat slower than wild-type yeast cells, but exhibited no auxotrophic growth requirements.


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