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

In Saccharomyces cerevisiae, methylation of the principal membrane sterol at C-24 produces the C-28 methyl group specific to ergosterol and represents one of the few structural differences between ergosterol and cholesterol. C-28 in S. cerevisiae has been suggested to be essential for the sparking function (W. J. Pinto and W. R. Nes, J. Biol. Chem. 258:4472-4476, 1983), a cell cycle event that may be required to enter G1 (C. Dahl, H.-P. Biemann, and J. Dahl, Proc. Natl. Acad. Sci. USA 84:4012-4016, 1987). The sterol biosynthetic pathway in S. cerevisiae was genetically altered to assess the functional role of the C-28 methyl group of ergosterol. ERG6, the putative structural gene for S-adenosylmethionine: delta 24-methyltransferase, which catalyzes C-24 methylation, was cloned, and haploid strains containing erg6 null alleles (erg6 delta 1 and erg6 delta ::LEU2) were generated. Although erg6 delta cells are unable to methylate ergosterol precursors at C-24, they exhibit normal vegatative growth, suggesting that C-28 sterols are not essential in S. cerevisiae. However, erg6 delta cells exhibit pleiotropic phenotypes that include defective conjugation, hypersensitivity to cycloheximide, resistance to nystatin, a severely diminished capacity for genetic transformation, and defective tryptophan uptake. These phenotypes reflect the role of ergosterol as a regulator of membrane permeability and fluidity. Genetic mapping experiments revealed that ERG6 is located on chromosome XIII, tightly linked to sec59.
Mol Cell Biol 1989 Aug
PMID:The yeast gene ERG6 is required for normal membrane function but is not essential for biosynthesis of the cell-cycle-sparking sterol. 267 74

Histamine metabolism, i.e., concentration of histamine and activities of histamine-degrading enzymes, histamine-N-methyltransferase (HMT), and diamine oxidase (DAO), were examined in the Arthus reaction induced in guinea pig skin. The specific activity of HMT was 44.12 +/- 3.80 pmole/min/mg protein and was about 15 times greater than that of DAO in control specimens. However, HMT activity decreased time dependently to 35% of the control at 3 hr and to 10% 48 hr after the initiation of the reaction. DAO activity increased to 150% till 1 hr followed by a linear decrease to 35% at 6 hr and to 10% at 48 hr. Histamine concentration showed a prominent linear decrease to 15% of the control at 2 hr followed by an increase to about 85% at 6 hr. This biphasic change seemed to be well explained by the dynamic changes in the activities of histamine-degrading enzymes. Such decrease in enzyme activities were not observed in other experimentally induced inflammations including dinitrochlorobenzene allergic and croton oil dermatitis. The addition of tissue extract from the Arthus reaction sites resulted in about 30% inhibition in both of two enzyme activities, suggesting the presence of some inhibitory factor(s) in the reaction sites.
Exp Mol Pathol 1986 Feb
PMID:Histamine metabolism in the Arthus reaction. 293 18

The concentrations of serotonin, tryptamine, dopamine, and tyramine were quantitatively determined in the Arthus reaction, since the activity of histamine-N-methyltransferase (HMT), a major histamine-metabolizing enzyme that had been demonstrated to be inhibited by such biogenic amines in vitro, decreased significantly in the reaction site. The concentrations of serotonin, tryptamine, and dopamine were unchanged in dinitrochlorobenzene allergic and croton oil dermatitis except for a slight increase of tryptamine in the latter. Tyramine was unable to be demonstrated quantitatively in all specimens tested. The concentration of serotonin decreased to about 30% that of the control level until 1 hr, followed by a prominent increase to about two-fold at 6 hr after the initiation of the Arthus reaction accompanying with a concomitant decrease in HMT activity. However, the concentrations of tryptamine and dopamine were rather decreased in the reaction site, and the net decrease of two amines was far greater than the increased amount of serotonin. The decrease in HMT activity is not stoichiometrically well elucidated from these results, and therefore, the presence of other hypothetic inhibitory factors that are increased in the Arthus reaction should be suspected.
Exp Mol Pathol 1987 Oct
PMID:Biogenic amines in the Arthus reaction. 295 59

An enzyme was isolated from a eucaryotic, Chlorella-like green alga infected with the virus PBCV-1 which exhibits type II restriction endonuclease activity. The enzyme recognized the sequence GATC and cleaved DNA 5' to the G. Methylation of deoxyadenosine in the GATC sequence inhibited enzyme activity. In vitro the enzyme cleaved host Chlorella nuclear DNA but not viral DNA because host DNA contains GATC and PBCV-1 DNA contains GmATC sequences. PBCV-1 DNA is probably methylated in vivo by the PBCV-1-induced methyltransferase described elsewhere (Y. Xia and J. L. Van Etten, Mol. Cell. Biol. 6:1440-1445). Restriction endonuclease activity was first detected 30 to 60 min after viral infection; the appearance of enzyme activity required de novo protein synthesis, and the enzyme is probably virus encoded. Appearance of enzyme activity coincided with the onset of host DNA degradation after PBCV-1 infection. We propose that the PBCV-1-induced restriction endonuclease participates in host DNA degradation and is part of a virus-induced restriction and modification system in PBCV-1-infected Chlorella cells.
Mol Cell Biol 1986 May
PMID:Restriction endonuclease activity induced by PBCV-1 virus infection of a Chlorella-like green alga. 302 90

Expression of the methyltransferase gene from Bacillus subtilis lysogenizing phage SP beta B was studied by analyzing the sensitivity of the hybrid plasmid DNAs to restriction by the enzymes BspRI, Hpall and Mspl. The gene produces the methylase M. BsuP beta BI with specificity for 5'-GGCC. The fragment carrying the SP beta B derived gene also directs the synthesis in E. coli of a second methylase activity (M. BsuP beta BII) with 5'-CCGG specificity. Indirect evidence suggests that the two SP beta B modification activities are encoded by the same gene.
Mol Gen Mikrobiol Virusol 1985 Feb
PMID:[Expression of cloned gene for methyltransferase from Bacillus subtilis bacteriophage SPbetaB]. 302 91

The DNA sequences of the diadenosine tetraphosphatase gene (apaH) and of the flanking regions were determined. Three other genes were identified in the flanking regions: ksgA, apaG and folA encoding, respectively, a 16 S rRNA methyltransferase, an unidentified protein of Mr 13,826 and dihydrofolate reductase, with the order folA-apaH-apaG-ksgA. The apaH gene is thus located between folA and ksgA at 1 min on the Escherichia coli chromosome linkage map and folA is transcribed clockwise, whereas ksgA, apaG and apaH are transcribed in the opposite direction. It was shown that ksgA, apaG and apaH can be expressed from a polycistronic mRNA originating from a promoter (p1) located upstream of ksgA. However, another promoter (p2) was found within the ksgA structural gene. This promoter, active in vivo, can account for p1-independent expression of the two distal cistrons, apaG and apaH. Finally, the effect on diadenosine tetraphosphatase over-production of a frameshift mutation causing premature translational termination of apaG suggests that expression of apaG and apaH is coupled at the translational level.
Mol Gen Genet 1986 Dec
PMID:The gene for Escherichia coli diadenosine tetraphosphatase is located immediately clockwise to folA and forms an operon with ksgA. 303 29

A high-molecular-weight protein complex that is capable of accurate transcription initiation and termination of vaccinia virus early genes without additional factors was demonstrated. The complex was solubilized by disruption of purified virions, freed of DNA by passage through a DEAE-cellulose column, and isolated by glycerol gradient sedimentation. All detectable RNA polymerase activity was associated with the transcription complex, whereas the majority of enzymes released from virus cores including mRNA (nucleoside-2'-O)methyltransferase, poly(A) polymerase, topoisomerase, nucleoside triphosphate phosphohydrolase II, protein kinase, and single-strand DNase sedimented more slowly. Activities corresponding to two enzymes, mRNA guanylyltransferase (capping enzyme) and nucleoside triphosphate phosphohydrolase I (DNA-dependent ATPase), partially sedimented with the complex. Silver-stained polyacrylamide gels, immunoblots, and autoradiographs confirmed the presence of subunits of vaccinia virus RNA polymerase, mRNA guanylyltransferase, and nucleoside triphosphate phosphohydrolase I, as well as additional unidentified polypeptides, in fractions with transcriptase activity. A possible role for the DNA-dependent ATPase was suggested by studies with ATP analogs with gamma-S or nonhydrolyzable beta-gamma-phosphodiester bonds. These analogs were used by vaccinia virus RNA polymerase to nonspecifically transcribe single-stranded DNA templates but did not support accurate transcription of early genes by the complex. Transcription also was sensitive to high concentrations of novobiocin; however, this effect could be attributed to inhibition of RNA polymerase or ATPase activities rather than topoisomerase.
Mol Cell Biol 1987 Jan
PMID:Sedimentation of an RNA polymerase complex from vaccinia virus that specifically initiates and terminates transcription. 303 83

The inactivation of elongation factor 2 (EF-2) by diphtheria toxin requires the presence of a post-translationally modified histidine residue in EF-2. This residue, diphthamide, has the structure 2-[3-carboxyamido-3-(trimethylammonio)propyl]histidine. The present work was undertaken to study the pathway of diphthamide biosynthesis using diphtheria toxin-resistant yeast mutants (Chen. J.-Y., Bodley, J. W., and Livingston, D. M. (1985) Mol. Cell. Biol. 5, 3357-3360) which are defective in diphthamide formation. We demonstrate here that one of these mutants (dph5) contains a toxin-resistant form of EF-2 which can be converted in vitro to a toxin-sensitive form through the action of an enzyme present in other yeast strains. Both this toxin-resistant EF-2 and its modifying enzyme have been partially purified and evidence is presented that the modifying enzyme is a specific S-adenosylmethionine:EF-2 methyltransferase. In vitro complementation to diphtheria toxin sensitivity required S-adenosylmethionine, and when partially purified components were incubated with [methyl-3H]S-adenosylmethionine, label was incorporated specifically into EF-2. Hydrolysis of labeled EF-2 yielded diphthine (the unamidated form of diphthamide) and a single chromatographically separable labeling intermediate. We conclude that the S-adenosylmethionine:EF-2 methyltransferase adds at least the last two of the three methyl groups present in diphthine and that this modification is sufficient to create diphtheria toxin sensitivity. Evidence is also presented for the existence of an ATP-dependent amidating enzyme which catalyzes the final step in the biosynthesis of diphthamide in EF-2.
 ...
PMID:Biosynthesis of diphthamide in Saccharomyces cerevisiae. Partial purification and characterization of a specific S-adenosylmethionine:elongation factor 2 methyltransferase. 304 77

The complexation of tRNA (adenine-1-)-methyltransferase from Thermus thermophilus HB8 (E.C.2.1.1.36) with Escherichia coli tRNA(Phe) and yeast tRNA1(Val) was investigated in a temperature range from 20 to 90 degrees C. The quantity of methylase subunits bounded with tRNA and the association constant (Ka) were determined by means of fluorescence quenching of the enzyme tryptophane residues by tRNA molecules. The number of enzyme subunits bounded with one tRNA molecule at temperatures 20-70 degrees C is equal to 8 +/- 2. The Ka values increase from (2 divided by 3).10(7) at 20 degrees C up to 8.5.10(7) M-1 at 70 degrees C. The temperature increase from 70 to 90 degrees C causes a decrease in the enzyme specific activity and in Ka values. In the temperature range from 75 to 90 degrees C a cooperative transition of methylase macromolecules into associates was observed. This association is accompanied by an increase of UV-light scattering and of fluorescence polarization coefficient of methylase tryptophane residues. In the absence of tRNA the size of enzyme associates (d) is evaluated to be more than 320 nm (d greater than or equal to lambda-320 nm), in the presence of tRNA-less than 320 nm (d much less than lambda-320 nm). An electron microscopic investigation of methylase and its complexes with tRNA at 20 degrees C revealed disk-like particles with a diameter and height of 8-11 nm and 4-5 nm, respectively. These disk-like methylase preparations dialized against distilled water form flexible polymeric rods with a diameter of 10-12 nm and the length of about several hundreds nm. During complexation of methylase with tRNA, in the same conditions as the dializes was carried out, large associates were not revealed.
Mol Biol (Mosk)
PMID:[Temperature-dependent structural changes in complexes of tRNA(adenine-1)-methyltransferase from Thermus thermophilus HB8 and tRNA studied by optical and electron microscope methods]. 305 94

Six mutant strains of Bacillus subtilis hypersensitive to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were shown to be deficient in the adaptive response to MNNG and termed ada mutants (Morohoshi and Munakata 1985). All the mutations mapped between the attSPO2 and lin loci on the chromosome. The mutant and wild-type (ada+) cells contained similar constitutive levels of O6-methylguanine-DNA methyltransferase activity. Pretreatment with low concentrations of MNNG increased the activity about nine-fold in the ada+ cells, while it uniformly decreased the activity in the ada cells. The pretreatment of three mutants (ada-3, ada-4, and ada-6) as well as ada+, augmented the activity of methylpurine-DNA glycosylase and rendered the cells resistant to the lethal and mutagenic effects of N-propyl- or N-butyl-N'-nitro-N-nitrosoguanidine. With the rest of the mutant strains (ada-1, ada-2, and ada-5), neither of such responses was elicited by the pretreatment. Thus, the former ada strains seem to have a defect in the gene specifically involved in the induction of the methyltransferase, while the latter ada strains have a defect in the gene controlling the adaptive response as a whole.
Mol Gen Genet 1986 Feb
PMID:Two classes of Bacillus subtilis mutants deficient in the adaptive response to simple alkylating agents. 308 20


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>