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At least 613 records · Page 34Linked to original sources
PubMed1999

Phenotypic reversal of the btn1 defects in yeast by chloroquine: a yeast model for Batten disease.

BTN1 of Saccharomyces cerevisiae encodes an ortholog of CLN3, the human Batten disease gene. We have reported previously that deletion of BTN1, btn1-Delta, resulted in a pH-dependent resistance to D-(-)-threo-2-amino-1-[p-nitrophenyl]-1,3-propanediol (ANP). This phenotype was caused by btn1-Delta strains having an elevated ability to acidify growth medium through an elevated activity of the plasma membrane H(+)-ATPase, resulting from a decreased vacuolar pH during early growth. We have determined that growing btn1-Delta strains in the presence of chloroquine reverses the resistance to ANP, decreases the rate of medium acidification, decreases the activity of plasma membrane H(+)-ATPase, and elevates vacuolar pH. However, an additional effect of this phenotypic reversal is that activity of plasma membrane H(+)-ATPase is decreased further and vacuolar pH is increased further as btn1-Delta strains continue to grow. This phenotypic reversal of btn1-Delta can be considered for developing a therapy for Batten disease.

Chloroquine↗
PubMed2001

Antioxidant system within yeast peroxisome. Biochemical and physiological characterization of CbPmp20 in the methylotrophic yeast Candida boidinii.

Candida boidinii Pmp20 (CbPmp20), a protein associated with the inner side of peroxisomal membrane, belongs to a recently identified protein family of antioxidant enzymes, the peroxiredoxins, which contain one cysteine residue. Pmp20 homologs containing the putative peroxisome targeting signal type 1 have also been identified in mammals and lower eukaryotes. However, the physiological function of these Pmp20 family proteins has been unclear. In this study, we investigated the biochemical and physiological functions of recombinant CbPmp20 protein in methanol-induced peroxisomes of C. boidinii using the PMP20-deleted strain of C. boidinii (pmp20Delta strain). The His(6)-tagged CbPmp20 fusion protein was found to have glutathione peroxidase activity in vitro toward alkyl hydroperoxides and H(2)O(2). Catalytic activity and dimerization of His(6)-CbPmp20 depended on the only cysteine residue corresponding to Cys(53). The pmp20Delta strain was found to have lost growth ability on methanol as a carbon and energy source. The pmp20Delta growth defect was rescued by CbPmp20, but neither CbPmp20 lacking the peroxisome targeting signal type 1 sequence nor CbPmp20 haboring the C53S mutation retrieved the growth defect. Interestingly, the pmp20Delta strain had a more severe growth defect than the cta1Delta strain, which lacks catalase, another antioxidant enzyme within the peroxisome. During incubation of these strains in methanol medium, the cta1Delta strain accumulated H(2)O(2), whereas the pmp20Delta strain did not. Therefore, it is speculated to be the main function of CbPmp20 is to decompose reactive oxygen species generated at peroxisomal membrane surface, e.g. lipid hydroperoxides, rather than to decompose H(2)O(2). In addition, we detected a physiological level of reduced glutathione in peroxisomal fraction of C. boidinii. These results may indicate a physiological role for CbPmp20 as an antioxidant enzyme within peroxisomes rich in reactive oxygen species.

Amino Acid Sequence↗
PubMed1979

[Usage of feeding yeast "Fermosin" grown on mineral oil distillate in animal nutrition. 2. Digestibility of the nutrients of Fermosin feeding yeast on broilers (chickens) and fattening pigs].

The digestibility of the nutrients of Fermosin was tested on pigs and the following values were ascertained: organic matter=86%, crude protein=89% and N-free extractives=83%. The net energy ascertained on the basis of the content of nutrients and the digestibility of the nutrients of Fermosin amounts to 617 energetic feed units for pigs/kg dry matter. The true digestibility of the amino acids of Fermosin was determined on pigs and chicken. For lysin the true digestibility was ascertained as 95% (pigs) and 73% (Broilers). Due to the different digestion abilities of the two animal species, corresponding differences in the digestibility of the other amino acids were found as well.

Animal Feed↗
PubMed2003

The fission yeast spo14+ gene encoding a functional homologue of budding yeast Sec12 is required for the development of forespore membranes.

The Schizosaccharomyces pombe spo14-B221 mutant was originally isolated as a sporulation-deficient mutant. However, the spo14(+) gene is essential for cell viability and growth. spo14(+) is identical to the previously characterized stl1(+) gene encoding a putative homologue of Saccharomyces cerevisiae Sec12, which is essential for protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus. In the spo14 mutant cells, ER-like membranes were accumulated beneath the plasma membrane and the ER/Golgi shuttling protein Rer1 remained in the ER. Sec12 is a guanine nucleotide exchange factor for the Sar1 GTPase. Overproduction of psr1(+) coding for an S. pombe Sar1 homologue suppressed both the sporulation defect of spo14-B221 and cold-sensitive growth of newly isolated spo14-6 and spo14-7 mutants. These results indicate that Spo14 is involved in early steps of the protein secretory pathway. The spo14-B221 allele carries a single nucleotide change in the branch point consensus of the fifth intron, which reduces the abundance of the spo14 mRNA. During meiosis II, the forespore membrane was initiated near spindle pole bodies; however, subsequent extension of the membrane was arrested before its closure into a sac. We conclude that Spo14 is responsible for the assembly of the forespore membrane by supplying membrane vesicles.

Amino Acid Sequence↗
PubMed1999

Partial purification of the yeast U2 snRNP reveals a novel yeast pre-mRNA splicing factor required for pre-spliceosome assembly.

We have partially purified the U2 snRNP of Saccharomyces cerevisiae. Identification of some proteins consistently found in the purified fractions by nanoelectrospray mass spectrometry indicated the presence of a novel splicing factor named Rse1p. The RSE1 gene is essential and codes for a 148.2 kDa protein. We demonstrated that Rse1p associates specifically with U2 snRNA at low salt concentrations. In addition, we showed that Rse1p is a component of the pre-spliceosome. Depletion of Rse1p and analysis of a conditional mutant indicated that Rse1p was required for efficient splicing in vivo. In vitro Rse1p is required for the formation of pre-spliceosomes. Database searches revealed that Rse1p is conserved in humans and that it belongs to a large protein family that includes polyadenylation factors and DNA repair proteins. The characteristics of Rse1p suggest that its human homologue could be a subunit of the SF3 splicing factor.

Amino Acid Sequence↗
PubMed1978

Properies of tRNAPhe from yeast carrying a spin label on the 3'-terminal. Interaction with yeast phenylalanyl-tRNA Synthetase and elongation factor Tu from Escherichia coli.

The 2-thioketo function of tRNAPhe-C-s2C-A in which the penultimate cytidine residue is replaced by 20thiocytidine can serve as a site of specific attachment of spin label. By alkylation of tRNAPhe-C-s2C-A with iodoacetamide or its spin label derivatives tRNAPhe-C-(acm)s2C-A or tRNAPheC-(SL)s2C-A are formed. The enzymatic phenylalanylation of these tRNAsPhe revealed that the 2-position of the penultimate cytidine can be modified without impairing this enzymatic reaction but there exists a sterical limitation for the subsituent on this position beyond which the tRNAPhe:phenylalanyl-tRNA synthetase recognition is not possible. Both Phe-tRNAPhe-C-(acm)s2C-A as well as Phe-tRNAPhe-C(SL)s2C-A form ternary complexes with EF-Tu.GTP. The part of the 3'-terminus of tRNAPhe where the additional substituents are attached is therefore not involved in the interaction with this elongation factor. This could be also demonstrated by ESR measurements of spin labelled tRNAsPhe. The correlation times, tauc, for tRNAPhe-C-(SL)s2C-A, Phe-tRNAPhe-C-(SL)s2C-A and Phe-tRNAPhe-C-(SL)s2C-A.EF-Tu:GTP are essentially identical indicating that the structure of the 3'-end of tRNAPhe is not influenced significantly by aminoacylation or ternary complex formation.

Amino Acyl-tRNA Synthetases↗