Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Saccharomycopsis (Candida) lipolytica direct cysteine synthesis is mediated by two different, simultaneously acting cysteine synthases: a low molecular mass (74,000 daltons) monofunctional enzyme (Km for O-acetyl-l-serine 23.5 mm) and a high molecular mass (220,000 daltons) bifunctional cysteine-homocysteine synthase (Km for O-acetyl-l-serine 55.0 mm). The latter enzyme is also involved in direct homocysteine synthesis from O-acetyl-l-homoserine (Km 11.9 mm). Evidence is presented that a fraction of homocysteine can be synthesized from cysteine via cystathionine. Our previous results (Morzycka & Paszewski, FEBS Lett., 1979, 101, 97-100; Mol. Gen. Genet., 1979, 174, 33-38) together with the data presented here strongly suggest that both S., lipolytica synthases are under control of the same regulatory system, together with the other enzymes of sulphur metabolism: ATP-sulphurylase and aryl-sulphatase. gamma-Cystathionase, an enzyme involved in cysteine synthesis from homocysteine, is controlled exclusively by cysteine.
Acta Biochim Pol 1982
PMID:Cysteine and homocysteine synthesis in Saccharomycopsis lipolytica; identification and characterization of two cysteine synthases. 718 Mar 27

Secondary structures of the N-terminal fragments of 18 preproteins were analysed taking advantage of the method of Chou & Fasman (Biochemistry, 1974, 13, 222-245; J. Mol. Biol., 1977, 115, 135-175) and the known sequences of amino acid residues. Positions of alpha-helices, beta-sheet structures and beta-turns in the linear primary structure of preproteins have been proposed. Also it has been suggested that the three-dimensional structures of the N-terminal fragments of preproteins are homologous, irrespective of the differences in their primary structures, length of polypeptide chains, and function. A three-dimensional model of the N-terminal fragment is given, comprising the regions responsible for transport and removal of the signal peptide from preprotein. The location of prelipoprotein region responding to signal protease, and the substrate spatial requirements of this enzyme have been hypothesized.
Acta Biochim Pol 1981
PMID:Homology of the predicted secondary structures of the N-terminal fragments of preproteins. 734 90

Many oncogenes associated with human sarcomas are composed of a fusion between transcription factors and the N-terminal portions of two similar RNA-binding proteins, TLS and EWS. Though the oncogenic fusion proteins lack the RNA-binding domain and do not bind RNA, the contribution from the N-terminal portion of the RNA-binding protein is essential for their transforming activity. TLS and EWS associate in vivo with RNA polymerase II (Pol II) transcripts. To learn more about the target gene specificity of this interaction, the localization of a Drosophila melanogaster protein that has extensive sequence identity to the C-terminal RNA-binding portions of TLS and EWS was studied in preparations of Drosophila polytene nuclei. cDNA clones encoding the full-length Drosophila TLS-EWS homolog, SARFH (stands for sarcoma-associated RNA-binding fly homolog), were isolated. Functional similarity to TLS and EWS was revealed by the association of SARFH with Pol II transcripts in mammalian cells and by the ability of SARFH to elicit homologous down-regulation of the levels of the mammalian proteins. The SARFH gene is expressed in the developing Drosophila embryo from the earliest stages of cellularization and is subsequently found in many cell types. In preparations of polytene chromosomes from salivary gland nuclei, SARFH antibodies recognize their target associated with the majority of active transcription units, revealed by colocalization with the phosphorylated form of RNA Pol II. We conclude that SARFH and, by homology, EWS and TLS participate in a function common to the expression of most genes transcribed by RNA Pol II.
Mol Cell Biol 1995 Aug
PMID:Association of SARFH (sarcoma-associated RNA-binding fly homolog) with regions of chromatin transcribed by RNA polymerase II. 762 47

We have subcloned an N-terminal extended protease gene of human immunodeficiency virus (HIV) type 1 that is encoded in the protease domain of the pol open reading frame into expression vector pGEX-KG. A relatively high level of expression of recombinant HIV-1 protease (PR) was achieved with isopropyl beta-D-thiogalactoside (IPTG) induction and glucose supplement. An isolation method consisting of denaturation of protein and followed by refolding was developed for releasing this recombinant HIV-1 PR into the soluble phase since most of the expressed protease was initially present in insoluble inclusion bodies. High purity of this recombinant HIV-1 PR was obtained by sequential purification using Sephadex G-50 gel filtration and CM-23 cellulose cation exchange chromatography, yielding the protease more than 1 mg per liter culture. N-terminal amino acid sequence analysis showed that the recombinant HIV-1 PR underwent autocleavage from the fusion protein during expression. SDS-PAGE indicated that the molecular weight of this recombinant HIV-1 PR is 11 kDa. This recombinant HIV-1 PR showed proteolytic activity for the synthetic peptide substrates corresponding to the sequence at the Gag MA/CA and Pol p6*/PR junctions. The purified enzyme whose specific activity for the heptapeptide SQNYPIV was 848.7 nmol*min-1*mg protease-1 also processed recombinant polyprotein Gag41 as its substrate.
Biochem Mol Biol Int 1995 Apr
PMID:Expression and purification of active form of HIV-1 protease from E.coli. 762 39

We have characterized a highly repetitive family, named Hy/Pol III, in the genome of the European salamanders Hydromantes (Plethodontidae). This family consists of short, tandemly repeated sequences organized in clusters, scattered through the genome as shown both by in situ hybridization to chromosomes and by Southern blot hybridization. The repeat unit is about 200 bp in length and it is a composite element since it contains a SINE-like retroposon with a tRNA structure, flanked by two short direct repeats. The whole element itself is bordered by two other direct repeats. The sequence data suggest that two elements, presumably derived from polymerase III transcripts, have been inserted one into the other, giving rise to the observed composite structure. During evolution the Hy/Pol III family was then amplified by tandem duplication at the DNA level. The inferred relationships between Hy/Pol III members from three representative species of the European Hydromantes suggests that a subfamily structure characterizes the evolutionary history of this family.
J Mol Evol 1995 Jun
PMID:A tandemly repeated DNA family originated from SINE-related elements in the European plethodontid salamanders (Amphibia, Urodela). 764 11

We used quantitative complementation assays to characterize individual DNA polymerase beta (Pol beta) mutants for their ability to function in DNA replication and DNA repair. We also describe a screen for detecting mutator activity of DNA polymerase beta mutants. By using these bioassays, together with DNA polymerase activity gels, we characterized 15 new DNA polymerase beta mutants that display a wide spectrum of phenotypes. Most of these mutants are generally defective in their ability to synthesize DNA. However, two of our Pol beta mutants show more complex phenotypes: they are able to function in DNA repair but unable to participate in DNA replication. One of our mutants displays mutator activity in vivo. Our work provides a model to study mutant mammalian enzymes in Escherichia coli with phenotypes that are otherwise difficult to assess.
Mol Gen Genet 1995 Jul 28
PMID:Characterization of DNA polymerase beta mutants with amino acid substitutions located in the C-terminal portion of the enzyme. 765 44

Human immunodeficiency virus type 1 (HIV-1) and other lentiviridae demonstrate a strong preference for the A-nucleotide, which can account for up to 40% of the viral RNA genome. The biological mechanism responsible for this nucleotide bias is currently unknown. The increased A-content of these viral genomes corresponds to the typical use of synonymous codons by all members of the lentiviral family (HIV, SIV, BIV, FIV, CAEV, EIAV, visna) and the human spuma retrovirus, but not by other retroviruses like the human T-cell leukemia viruses HTLV-1 and HTLV-II. In this article, we analyzed A-bias for all codon groups in all open reading frames of several lentiviruses. The extent of lentiviral codon bias could be related to host cellular translation. By calculating codon bias indices (CBIs), we were able to demonstrate an inverse correlation between the extent of codon bias and the rate of translation of individual reading frames in these viruses. Specifically, the shift toward A-rich codons is more pronounced in pol than in gag lentiviral genes. Since it is known that Gag synthesis exceeds Pol synthesis by a factor of 20 due to infrequent ribosomal frame-shifting during translation of the gap-pol mRNA molecule, we propose that the aminoacyl-tRNA availability in the host cell restricts the lentiviral preference for A-rich codons. In addition, less A-nucleotides were found in regions of the viral genome encoding multiple functions; e.g., overlapping reading frames (tat-rev-env) or in genes that overlap regulatory sequences (nef-LTR region).(ABSTRACT TRUNCATED AT 250 WORDS)
J Mol Evol 1995 Aug
PMID:The tendency of lentiviral open reading frames to become A-rich: constraints imposed by viral genome organization and cellular tRNA availability. 766 42

RNA polymerase III transcription of genes with external promoters only (e.g. U6 snRNA) or containing in addition an internal B box (selenocysteine tRNA(Sec)) is stimulated by upstream elements; a distal sequence element (DSE) for U6 or an activator element in the tRNA(Sec) gene. In contrast to the composite structure of the DSE which requires an octamer motif, the Xenopus tRNA(Sec) activator element contains an SPH motif only. In vivo transcription is optimally stimulated by SPH in an absolute octamer-independent manner since adding octamer does not induce superstimulation. Experiments performed in the work presented here led to the following observations. Co-operation between SPH and octamer motifs can be detected in two distinct cases: first when these motifs are placed in front of B box-less tRNA(Sec) or U6 external promoters and second, if either element of the external promoter (proximal sequence element or TATA element), or the SPH motif itself, are altered. Altogether, our data provide evidence that an SPH motif can function alone in an optimized promoter only. In contrast, an octamer becomes indispensable when the basal promoter is weak or disabled. It follows that module composition of Pol III transcriptional activator elements is dependent on the structure and strength of the promoter. This reveals the existence of cross-talk between activator and promoter elements, mediated by the bound transcription factors, which are thus able to compensate for each other in order to allow successful assembly of the transcription complex.
J Mol Biol 1993 Nov 20
PMID:Promoter strength and structure dictate module composition in RNA polymerase III transcriptional activator elements. 769 50

We have developed a system for mutational analysis of Saccharomyces cerevisiae ribosomal RNA in vivo in which yeast cells can be made completely dependent on mutant rRNA and ribosomes by a simple switch in carbon source. The system is based on a yeast strain defective in RNA polymerase I (Pol I) transcription [Nogi et al. (1991) Proc. Natl. Acad. Sci. USA 88, 3962-3966]. This normally inviable strain was rescued by integration of multiple copies of the complete 37S pre-rRNA operon under control of the inducible, Pol II-transcribed GAL7 promoter into the rDNA repeat on chromosome XII. The resulting YJV100 strain can only grow on medium containing galactose as the carbon source. A second, episomal vector was constructed in which the rDNA unit was placed under control of the constitutive PGK1 promoter. YJV100 cells transformed with this vector are now also able to grow on glucose-based medium making the cells completely dependent on plasmid-encoded rRNA. We show that the Pol II-transcribed pre-rRNA is processed and assembled similarly to authentic Pol I-synthesised pre-rRNA, making this 'in vivo Pol II system' suitable for the detailed analysis of rRNA mutations, even highly deleterious ones, affecting ribosome biogenesis or function. A clear demonstration of this is our finding that an insertion into variable region V8 in 17S rRNA, previously judged to be neutral with respect to processing of 17S rRNA, its assembly into 40S subunits and the polysomal distribution of these subunits [Musters et al. (1989), Mol. Cell. Biol. 9, 551-559], is in fact a lethal mutation.
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PMID:Development and application of an in vivo system to study yeast ribosomal RNA biogenesis and function. 773 24

Two forms of Mod5p, a tRNA modification enzyme, are found in three intracellular compartments, mitochondria, cytoplasm and nucleus, but are encoded by a single MOD5 gene. The two forms of the enzyme, Mod5p-I and Mod5p-II differ at the N-termini and are produced by initiation of translation at different start codons. Mod5p-I does contain a mitochondrial targeting signal and is distributed between mitochondria and cytoplasm, whereas Mod5p-II is found in the cytosol and nucleus (Boguta, M., et al. 1994, Mol. Cell. Biol. 14, 2298-2306). In the present work mutants which mislocalize the Mod5p-I enzyme were isolated. The screen was based on a correlation between the amount of cytosolic protein and the efficiency of tRNA mediated suppression. Identification of mutants is possible because a red pigment accumulates in the cells unable to suppress an ade2-1 nonsense allele. The maf1 mutant, with an altered intracellular localization of the Mod5p-I protein, was isolated. Immunofluorescence data suggest that the mutation causes mislocalization of the Mod5p-I to the nucleus.
Acta Biochim Pol 1994
PMID:maf1 mutation alters the subcellular localization of the Mod5 protein in yeast. 773 62


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