A deletion that includes the segment coding for the signal peptidase cleavage site delays release of Saccharomyces cerevisiae acid phosphatase from the endoplasmic reticulum

1986 ◽  
Vol 6 (2) ◽  
pp. 723-729
Author(s):  
R Haguenauer-Tsapis ◽  
M Nagy ◽  
A Ryter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Acid Phosphatase ◽  
Cleavage Site ◽  
Ultrastructural Localization ◽  
Signal Peptidase ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
Sugar Chains ◽  
Pho5 Gene

We studied ultrastructural localization of acid phosphatase in derepressed Saccharomyces cerevisiae cells transformed with a multicopy plasmid carrying either the wild-type PHO5 gene or a PHO5 gene deleted in the region overlapping the signal peptidase cleavage site. Wild-type enzyme was located in the cell wall, as was 50% of the modified protein, which carried high-mannose-sugar chains. The remaining 50% of the protein was active and core glycosylated, and it accumulated in the endoplasmic reticulum cisternae. The signal peptide remained uncleaved in both forms. Cells expressing the modified protein exhibited an exaggerated endoplasmic reticulum with dilated lumen.

scholarly journals A deletion that includes the segment coding for the signal peptidase cleavage site delays release of Saccharomyces cerevisiae acid phosphatase from the endoplasmic reticulum.

1986 ◽  
Vol 6 (2) ◽  
pp. 723-729 ◽  
Author(s):  
R Haguenauer-Tsapis ◽  
M Nagy ◽  
A Ryter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Acid Phosphatase ◽  
Cleavage Site ◽  
Ultrastructural Localization ◽  
Signal Peptidase ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
Sugar Chains ◽  
Pho5 Gene

We studied ultrastructural localization of acid phosphatase in derepressed Saccharomyces cerevisiae cells transformed with a multicopy plasmid carrying either the wild-type PHO5 gene or a PHO5 gene deleted in the region overlapping the signal peptidase cleavage site. Wild-type enzyme was located in the cell wall, as was 50% of the modified protein, which carried high-mannose-sugar chains. The remaining 50% of the protein was active and core glycosylated, and it accumulated in the endoplasmic reticulum cisternae. The signal peptide remained uncleaved in both forms. Cells expressing the modified protein exhibited an exaggerated endoplasmic reticulum with dilated lumen.

A deletion that includes the signal peptidase cleavage site impairs processing, glycosylation, and secretion of cell surface yeast acid phosphatase

1984 ◽  
Vol 4 (12) ◽  
pp. 2668-2675
Author(s):  
R Haguenauer-Tsapis ◽  
A Hinnen
Keyword(s):  
Acid Phosphatase ◽  
Cell Surface ◽  
Cleavage Site ◽  
Signal Peptidase ◽  
Wild Type ◽  
Gene Coding ◽  
High Copy Number Plasmid ◽  
Type Gene ◽  
Amino Acid Segment ◽  
Peptide Core

We transformed Saccharomyces cerevisiae with a high-copy-number plasmid carrying either the wild-type gene coding for a repressible cell surface acid phosphatase or two modified genes whose products lack a 13- or 14-amino-acid segment spanning or immediately adjacent to the signal peptidase cleavage site. The wild-type gene product underwent proteolytic cleavage of the signal peptide, core glycosylation, and outer chain glycosylation. The deletion spanning the signal peptidase cleavage site led to an unprocessed protein. This modified protein exhibited core glycosylation, whereas its outer chain glycosylation was severely inhibited. Secretion of the deleted protein was impaired, and active enzyme accumulated within the cell. The deletion immediately adjacent to the signal peptidase cleavage site exhibited only a small decrease in the efficiency of processing and had no effect on the efficiency of secretion.

scholarly journals A deletion that includes the signal peptidase cleavage site impairs processing, glycosylation, and secretion of cell surface yeast acid phosphatase.

1984 ◽  
Vol 4 (12) ◽  
pp. 2668-2675 ◽  
Author(s):  
R Haguenauer-Tsapis ◽  
A Hinnen
Keyword(s):  
Acid Phosphatase ◽  
Cell Surface ◽  
Cleavage Site ◽  
Signal Peptidase ◽  
Wild Type ◽  
Gene Coding ◽  
High Copy Number Plasmid ◽  
Type Gene ◽  
Amino Acid Segment ◽  
Peptide Core

We transformed Saccharomyces cerevisiae with a high-copy-number plasmid carrying either the wild-type gene coding for a repressible cell surface acid phosphatase or two modified genes whose products lack a 13- or 14-amino-acid segment spanning or immediately adjacent to the signal peptidase cleavage site. The wild-type gene product underwent proteolytic cleavage of the signal peptide, core glycosylation, and outer chain glycosylation. The deletion spanning the signal peptidase cleavage site led to an unprocessed protein. This modified protein exhibited core glycosylation, whereas its outer chain glycosylation was severely inhibited. Secretion of the deleted protein was impaired, and active enzyme accumulated within the cell. The deletion immediately adjacent to the signal peptidase cleavage site exhibited only a small decrease in the efficiency of processing and had no effect on the efficiency of secretion.

scholarly journals sir2 mutants of Kluyveromyces lactis are hypersensitive to DNA-targeting drugs.

1994 ◽  
Vol 14 (7) ◽  
pp. 4501-4508 ◽  
Author(s):  
X J Chen ◽  
G D Clark-Walker
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Function ◽  
Kluyveromyces Lactis ◽  
Functional Equivalence ◽  
Striking Difference ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
Dna Targeting ◽  
Mating Efficiency ◽  
Type Gene

A Kluyveromyces lactis mutant, hypersensitive to the DNA-targeting drugs ethidium bromide (EtBr), berenil, and HOE15030, can be complemented by a wild-type gene with homology to SIR2 of Saccharomyces cerevisiae (ScSIR2). The deduced amino acid sequence of the K. lactis Sir2 protein has 53% identity with ScSir2 protein but is 108 residues longer. K. lactis sir2 mutants show decreased mating efficiency, deficiency in sporulation, an increase in recombination at the ribosomal DNA locus, and EtBr-induced death. Some functional equivalence between the Sir2 proteins of K. lactis and S. cerevisiae has been demonstrated by introduction of ScSIR2 into a sir2 mutant of K. lactis. Expression of ScSIR2 on a multicopy plasmid restores resistance to EtBr and complements sporulation deficiency. Similarly, mating efficiency of a sir2 mutant of S. cerevisiae is partially restored by K. lactis SIR2 on a multicopy plasmid. Although these observations suggest that there has been some conservation of Sir2 protein function, a striking difference is that sir2 mutants of S. cerevisiae, unlike their K. lactis counterparts, are not hypersensitive to DNA-targeting drugs.

scholarly journals Characterization of a gene product (Sec53p) required for protein assembly in the yeast endoplasmic reticulum.

1985 ◽  
Vol 101 (6) ◽  
pp. 2374-2382 ◽  
Author(s):  
M Bernstein ◽  
W Hoffmann ◽  
G Ammerer ◽  
R Schekman
Keyword(s):  
Endoplasmic Reticulum ◽  
Gene Fusion ◽  
Protein Assembly ◽  
Open Reading Frame ◽  
Cell Fractionation ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
Cytosol Fraction ◽  
Reading Frame

SEC53, a gene that is required for completion of assembly of proteins in the endoplasmic reticulum in yeast, has been cloned, sequenced, and the product localized by cell fractionation. Complementation of a sec53 mutation is achieved with unique plasmids from genomic or cDNA expression banks. These inserts contain the authentic gene, a cloned copy of which integrates at the sec53 locus. An open reading frame in the insert predicts a 29-kD protein with no significant hydrophobic character. This prediction is confirmed by detection of a 28-kD protein overproduced in cells that carry SEC53 on a multicopy plasmid. To follow Sec53p more directly, a LacZ-SEC53 gene fusion has been constructed which allows the isolation of a hybrid protein for use in production of antibody. With such an antibody, quantitative immune decoration has shown that the sec53-6 mutation decreases the level of Sec53p at 37 degrees C, while levels comparable to wild-type are seen at 24 degrees C. An eightfold overproduction of Sec53p accompanies transformation of cells with a multicopy plasmid containing SEC53. Cell fractionation, performed with conditions that preserve the lumenal content of the endoplasmic reticulum (ER), shows Sec53p highly enriched in the cytosol fraction. We suggest that Sec53p acts indirectly to facilitate assembly in the ER, possibly by interacting with a stable ER component, or by providing a small molecule, other than an oligosaccharide precursor, necessary for the assembly event.

scholarly journals Internal cleavage of the human cytomegalovirus UL37 immediate-early glycoprotein and divergent trafficking of its proteolytic fragments

2004 ◽  
Vol 85 (7) ◽  
pp. 1989-1994 ◽  
Author(s):  
Manohara S. Mavinakere ◽  
Anamaris M. Colberg-Poley
Keyword(s):  
Endoplasmic Reticulum ◽  
Human Cytomegalovirus ◽  
Cleavage Site ◽  
Immediate Early ◽  
Signal Peptidase ◽  
Signal Sequences ◽  
Terminal Fragment ◽  
Exon 1

The human cytomegalovirus UL37 gene encodes at least three isoforms, which share N-terminal UL37 exon 1 (UL37x1) sequences. UL37 proteins traffic dually into the endoplasmic reticulum (ER) and to mitochondria. Trafficking of the UL37 glycoprotein (gpUL37) in relation to its post-translational processing was investigated. gpUL37 is internally cleaved in the ER and its products traffic differentially. Its C-terminal fragment (UL37COOH) is ER-localized and N-glycosylated. Unlike conventional ER signal sequences, its N-terminal () fragment is stable and traffics to mitochondria. Inhibition of N-glycosylation did not block pUL37 cleavage and dramatically decreased the levels of but not of UL37COOH. pUL37M, which differs from gpUL37 by the lack of residues 178–262 and hence the UL37x3 consensus signal peptidase cleavage site, traffics into the ER and mitochondria, but is neither cleaved nor N-glycosylated. This finding of a relationship between ER processing and mitochondrial importation of UL37 proteins is unique for herpesvirus proteins.

scholarly journals tRNA thiolation links translation to stress responses in Saccharomyces cerevisiae

2015 ◽  
Vol 26 (2) ◽  
pp. 270-282 ◽  
Author(s):  
Jadyn R. Damon ◽  
David Pincus ◽  
Hidde L. Ploegh
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Elevated Temperature ◽  
Heat Shock ◽  
Stress Responses ◽  
Wild Type ◽  
Trna Modifications ◽  
Shock Response ◽  
Tightly Coupled

Although tRNA modifications have been well catalogued, the precise functions of many modifications and their roles in mediating gene expression are still being elucidated. Whereas tRNA modifications were long assumed to be constitutive, it is now apparent that the modification status of tRNAs changes in response to different environmental conditions. The URM1 pathway is required for thiolation of the cytoplasmic tRNAs tGluUUC, tGlnUUG, and tLysUUU in Saccharomyces cerevisiae. We demonstrate that URM1 pathway mutants have impaired translation, which results in increased basal activation of the Hsf1-mediated heat shock response; we also find that tRNA thiolation levels in wild-type cells decrease when cells are grown at elevated temperature. We show that defects in tRNA thiolation can be conditionally advantageous, conferring resistance to endoplasmic reticulum stress. URM1 pathway proteins are unstable and hence are more sensitive to changes in the translational capacity of cells, which is decreased in cells experiencing stresses. We propose a model in which a stress-induced decrease in translation results in decreased levels of URM1 pathway components, which results in decreased tRNA thiolation levels, which further serves to decrease translation. This mechanism ensures that tRNA thiolation and translation are tightly coupled and coregulated according to need.

Recycling of the yeast v-SNARE Sec22p involves COPI-proteins and the ER transmembrane proteins Ufe1p and Sec20p

1998 ◽  
Vol 111 (11) ◽  
pp. 1507-1520 ◽  
Author(s):  
W. Ballensiefen ◽  
D. Ossipov ◽  
H.D. Schmitt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Immunofluorescence Microscopy ◽  
Transmembrane Proteins ◽  
Retrograde Transport ◽  
Subcellular Fractionation ◽  
Hybrid Protein ◽  
Wild Type ◽  
Alpha Factor ◽  
Membrane Compartments

Vesicle-specific SNAP receptors (v-SNAREs) are believed to cycle between consecutive membrane compartments. The v-SNARE Sec22(Sly2)p mediates the targeting of vesicles between endoplasmic reticulum (ER) and early Golgi of Saccharomyces cerevisiae. To analyze factors involved in targeting of Sec22(Sly2)p, an alpha-factor-tagged Sec22 protein (Sec22-alpha) was employed. Only on reaching the late Golgi, can alpha-factor be cleaved from this hybrid protein by Kex2p, a protease localized in this compartment. In wild-type cells Kex2p-cleavage is observed only when Sec22-alpha is greatly overproduced. Immunofluorescence microscopy and subcellular fractionation studies showed that Sec22-alpha is returned to the ER from the late Golgi (Kex2p) compartment. When Sec22-alpha is expressed in wild-type cells at levels comparable to the quantities of endogenous Sec22p, very little of this protein is cleaved by Kex2p. Efficient cleavage, however, occurs in mutants defective in the retrograde transport of different ER-resident proteins indicating that Sec22-alpha rapidly reaches the late Golgi of these cells. These mutants (sec20-1, sec21-1, sec27-1 and ufe1-1) reveal Golgi structures when stained for Sec22-alpha and do not show the ER-immunofluorescence observed in wild-type cells. These results show consistently that Sec22p recycles from the Golgi back to the ER and that this recycling involves retrograde COPI vesicles.

scholarly journals Processing of Human Cytomegalovirus UL37 Mutant Glycoproteins in the Endoplasmic Reticulum Lumen prior to Mitochondrial Importation

2006 ◽  
Vol 80 (14) ◽  
pp. 6771-6783 ◽  
Author(s):  
Manohara S. Mavinakere ◽  
Chad D. Williamson ◽  
Victor S. Goldmacher ◽  
Anamaris M. Colberg-Poley
Keyword(s):  
Endoplasmic Reticulum ◽  
Human Cytomegalovirus ◽  
Cleavage Site ◽  
Secretory Pathway ◽  
Signal Peptidase ◽  
Protein Abundance ◽  
Hydrophobic Core ◽  
Terminal Fragment ◽  
Signal Peptidase I ◽  
Α Helix

ABSTRACT The human cytomegalovirus (HCMV) UL37 glycoprotein (gpUL37) is internally cleaved and its products divergently traffic to mitochondria or are retained in the secretory pathway. To define the requirements for gpUL37 cleavage, residues −1 and −3 of the consensus endoplasmic reticulum (ER) signal peptidase I site within exon 3 (UL37x3) were replaced by bulky tyrosines (gpUL37 cleavage site mutant I). Internal cleavage of this UL37x3 mutant was inhibited, verifying usage of the consensus site at amino acids (aa) 193/194. The full-length mitochondrial species of gpUL37 cleavage site mutant I was N glycosylated and endoglycosidase H sensitive, indicating that ER translocation and processing took place prior to its mitochondrial importation. Moreover, these results suggest that internal cleavage of gpUL37 is not necessary for its N glycosylation. Partial deletion or disruption of the UL37 hydrophobic core immediately upstream of the cleavage site resulted in decreased protein abundance, suggesting that the UL37x3 hydrophobic α-helix contributes to either correct folding or stability of gpUL37. Insertion of the UL37x3 hydrophobic core and cleavage site into pUL37M, a splice variant of gpUL37 which lacks these sequences and is neither proteolytically cleaved nor N glycosylated, resulted in its internal cleavage and N glycosylation. Its NH2-terminal fragment, pUL37M-NH2, was detected more abundantly in mitochondria, while its N-glycosylated C-terminal fragment, gpUL37M-COOH, was detected predominantly in the ER in a manner analogous to that of gpUL37 cleavage products. These results indicate that UL37x3 aa 178 to 205 are prerequisite for gpUL37 internal cleavage and alter UL37 protein topology allowing N glycosylation of its C-terminal sequences. In contrast, the NH2-terminal UL37x1 hydrophobic leader, present in pUL37x1, pUL37M, and gpUL37, is not cleaved from mature UL37 protein, retaining a membrane anchor for UL37 isoforms during trafficking. Taken together, these results suggest that HCMV gpUL37 undergoes sequential trafficking, during which it is ER translocated, processed, and then mitochondrially imported.

scholarly journals The GTS1 gene, which contains a Gly-Thr repeat, affects the timing of budding and cell size of the yeast Saccharomyces cerevisiae.

1994 ◽  
Vol 14 (8) ◽  
pp. 5569-5578 ◽  
Author(s):  
K Mitsui ◽  
S Yaguchi ◽  
K Tsurugi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Cell Size ◽  
Single Cells ◽  
Exponential Growth Phase ◽  
Restrictive Temperature ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mean Cell Volume

A gene with an open reading frame encoding a protein of 417 amino acid residues with a Gly-Thr repeat was isolated from the yeast Saccharomyces cerevisiae by using synthetic oligonucleotides encoding three Gly-Thr dimers as probes. The deduced amino acid sequence showed partial homology to the clock-affecting gene, per, of Drosophila melanogaster in the regions including the GT repeat. The function of the gene, named GTS1, was examined by characterizing the phenotypes of transformants with different copy numbers of the GTS1 gene produced either by inactivating the GTS1 gene by gene disruption (TM delta gts1) or by transformation with multicopy plasmid pPER119 (TMpGTS1). They grew at similar rates during the exponential growth phase, but the lag phases were shorter for TM delta gts1 and longer for TMpGTS1 cells than that for the wild type. Analyses of their cell cycle parameters using synchronized cells revealed that the unbudding period changed as a function of gene dosage; that is, the periods of TM delta gts1 and TMpGTS1 were about 20% shorter and longer, respectively, than that of the wild-type. Another significant change in the transformants was detected in the distribution of the cell size. The mean cell volume of the TM delta gts1 cells in the unbudded period (single cells) was 27% smaller than that of single wild-type cells, whereas that of single TMpGTS1 cells was 48% larger. Furthermore, in the temperature-sensitive cdc4 mutant, the GTS1 gene affected the timing of budding at the restrictive temperature. Thus, the GTS1 gene product appears to modulate the timing of budding to obtain an appropriate cell size independent of the DNA replication cycle.

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