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Per Sunnerhagen

Publications and source records attributed to Per Sunnerhagen.

9 recordsLinked to original sources
PubMed2006

A peroxisomal glutathione transferase of Saccharomyces cerevisiae is functionally related to sulfur amino acid metabolism.

Saccharomyces cerevisiae cells contain three omega-class glutathione transferases with glutaredoxin activity (Gto1, Gto2, and Gto3), in addition to two glutathione transferases (Gtt1 and Gtt2) not classifiable into standard classes. Gto1 is located at the peroxisomes, where it is targeted through a PTS1-type sequence, whereas Gto2 and Gto3 are in the cytosol. Among the GTO genes, GTO2 shows the strongest induction of expression by agents such as diamide, 1-chloro-2,4-dinitrobenzene, tert-butyl hydroperoxide or cadmium, in a manner that is dependent on transcriptional factors Yap1 and/or Msn2/4. Diamide and 1-chloro-2,4-dinitrobenzene (causing depletion of reduced glutathione) also induce expression of GTO1 over basal levels. Phenotypic analyses with single and multiple mutants in the S. cerevisiae glutathione transferase genes show that, in the absence of Gto1 and the two Gtt proteins, cells display increased sensitivity to cadmium. A gto1-null mutant also shows growth defects on oleic acid-based medium, which is indicative of abnormal peroxisomal functions, and altered expression of genes related to sulfur amino acid metabolism. As a consequence, growth of the gto1 mutant is delayed in growth medium without lysine, serine, or threonine, and the mutant cells have low levels of reduced glutathione. The role of Gto1 at the S. cerevisiae peroxisomes could be related to the redox regulation of the Str3 cystathionine beta-lyase protein. This protein is also located at the peroxisomes in S. cerevisiae, where it is involved in transulfuration of cysteine into homocysteine, and requires a conserved cysteine residue for its biological activity.

Amino Acid Sequence↗
PubMed2006

Genome-wide expression profile of the mnn2 Delta mutant of Saccharomyces cerevisiae.

The MNN2 gene of S. cerevisiae encodes an alpha (1,2) mannosyl transferase required for branching the outer chain of N-linked oligosaccharides (Rayner J.C. and Munro S. 1998. J. Biol. Chem. 273: 26836-26843) and it also seems to have some effect on the transfer of mannosyl phosphate groups to the inner core (Olivero I. et al. 2000. FEBS Lett. 475: 111-116). In order to reveal possible interactions of MNN2 expression with other cellular pathways, we analyzed the transcriptome of the deletion mutant S. cerevisiae mnn2 Delta using cDNA microarrays. We found 151 genes that showed an altered expression level of > or =2-fold, 58 of them up-regulated and 93 down-regulated. Quite a high proportion of these genes (29%) encode unclassified proteins. In contrast to other defects affecting the integrity of the cell wall, deletion of MNN2 does not stimulate the expression of any of the genes included in the previously defined 'cell wall compensatory cluster' (Lagorce et al. 2003. J. Biol. Chem. 278: 20345-20357). We also found that 15% of the selected genes are related to central metabolic pathways. In addition, the mnn2 Delta strain seems to have a certain level of stimulation of DNA processing reactions while some genes involved in intracellular transport pathways are under-regulated.

Gene Deletion↗
PubMed2005

Rck2 is required for reprogramming of ribosomes during oxidative stress.

Rck2 is a mitogen-activated protein kinase-activated protein kinase in yeast implicated in translational regulation. rck2Delta mutants are mildly sensitive to oxidative stress, a condition that causes dissociation of actively translating ribosomes (polysomes). In rck2Delta cells, polysomes are lost to an even higher degree than in the wild-type upon stress. Cells overexpressing the catalytically inactive rck2-kd allele are highly sensitive to oxidative stress. In such cells, dissociation of polysomes upon stress was instead greatly delayed. The protein synthesis rate decreased to a similar degree as in wild-type cells, however, indicating that in rck2-kd cells, the polysome complexes were inactive. Array analyses of total and polysome-associated mRNAs revealed major deregulation of the translational machinery in rck2 mutant cells. This involves transcripts for cytosolic ribosomal proteins and for processing and assembly of ribosomes. In rck2Delta cells, weakly transcribed mRNAs associate more avidly with polysomes than in wild-type cells, whereas the opposite holds true for rck2-kd cells. This is consistent with perturbed regulation of translation elongation, which is predicted to alter the ratio between mRNAs with and without strong entry sites at ribosomes. We infer that imbalances in the translational apparatus are a major reason for the inability of these cells to respond to stress.

Alleles↗
PubMed2005

Degradation of Saccharomyces cervisiae Rck2 upon exposure of cells to high levels of zinc is dependent on Pep4.

In undisturbed cells, the MAPK-activated protein kinase Rck2 of Saccharomyces cerevisiae is a stable protein with a turnover time exceeding 60 min. However, we have found that Rck2 is subject to intracellular degradation after exposure of cells to Zn2+ concentrations of 5 mM or more. In high-zinc medium, most of the Rck2 pool is degraded within 5 min. This degradation is blocked by inhibiting the vacuolar proteolytic pathway with the protease inhibitor phenyl methyl sulphonyl fluoride or by mutation of the PEP4 gene. By contrast, blocking the proteasomal pathway with the inhibitor MG132 does not prevent Rck2 degradation upon addition of Zn2+, nor is degradation inhibited in the proteasomal mutations pre1 pre2, cim3, or cim5. The stability of Rck2 is not affected by any of the other stress conditions examined, or by growth rate. Possible mechanisms of the degradation of Rck2 under high zinc conditions, and its physiological significance, are discussed.

Aspartic Acid Endopeptidases↗
PubMed2004

Rck1 and Rck2 MAPKAP kinases and the HOG pathway are required for oxidative stress resistance.

We demonstrate a role in oxidative and metal stress resistance for the MAPK-activated protein kinases Rck1 and Rck2 in Saccharomyces cerevisiae. We show that Hog1 is robustly phosphorylated in a Pbs2-dependent way during oxidative stress, and that Rck2 also is phosphorylated under these circumstances. Hog1 concentrates in the nucleus in oxidative stress. Hog1 localization is partially dependent on Rck2, as rck2 cells have more nuclear Hog1 than wild-type cells. We find several proteins with a role in oxidative stress resistance using Rck1 or Rck2 as baits in a two-hybrid screen. We identify the transcription factor Yap2 as a putative target for Rck1, and the Zn2+ transporter Zrc1 as a target for Rck2. Yap2 is normally cytoplasmic, but rapidly migrates to the nucleus upon exposure to oxidative stress agents. In a fraction of untreated pbs2 cells, Yap2 is nuclear. Zrc1 co-immunoprecipitates with Rck2, and ZRC1 is genetically downstream of RCK2. These data connect activation of the Hog1 MAPK cascade with effectors having a role in oxidative stress resistance.

Animals↗
PubMed2003

Replication proteins influence the maintenance of telomere length and telomerase protein stability.

We investigated the effects of fission yeast replication genes on telomere length maintenance and identified 20 mutant alleles that confer lengthening or shortening of telomeres. The telomere elongation was telomerase dependent in the replication mutants analyzed. Furthermore, the telomerase catalytic subunit, Trt1, and the principal initiation and lagging-strand synthesis DNA polymerase, Polalpha, were reciprocally coimmunoprecipitated, indicating these proteins physically coexist as a complex in vivo. In a polalpha mutant that exhibited abnormal telomere lengthening and slightly reduced telomere position effect, the cellular level of the Trt1 protein was significantly lower and the coimmunoprecipitation of Trt1 and Polalpha was severely compromised compared to those in the wild-type polalpha cells. Interestingly, ectopic expression of wild-type polalpha in this polalpha mutant restored the cellular Trt1 protein to the wild-type level and shortened the telomeres to near-wild-type length. These results suggest that there is a close physical relationship between the replication and telomerase complexes. Thus, mutation of a component of the replication complex can affect the telomeric complex in maintaining both telomere length equilibrium and telomerase protein stability.

Catalytic Domain↗
PubMed2002

Prospects for functional genomics in Schizosaccharomyces pombe.

Schizosaccharomyces pombe is well established as an experimental organism for basic research, with well developed technologies for molecular biology, genetics and cell biology. Its full genome sequence has recently been published. Here, the prerequisites for functional genomics studies in Sch. pombe are examined and compared with those of some established prominent functional genomics model organisms, especially Saccharomyces cerevisiae. It is argued that functional genomics studies in certain areas of cellular and molecular biology could potentially be more efficiently performed in Sch. pombe than in most other experimental organisms.

Drug Evaluation, Preclinical↗
PubMed2002

Functional analysis of yeast gene families involved in metabolism of vitamins B1 and B6.

In order to clarify their physiological functions, we have undertaken a characterization of the three-membered gene families SNZ1-3 and SNO1-3. In media lacking vitamin B(6), SNZ1 and SNO1 were both required for growth in certain conditions, but neither SNZ2, SNZ3, SNO2 nor SNO3 were required. Copies 2 and 3 of the gene products have, in spite of their extremely close sequence similarity, slightly different functions in the cell. We have also found that copies 2 and 3 are activated by the lack of thiamine and that the Snz proteins physically interact with the thiamine biosynthesis Thi5 protein family. Whereas copy 1 is required for conditions in which B(6) is essential for growth, copies 2 and 3 seem more related with B(1) biosynthesis during the exponential phase.

Blotting, Northern↗