Information on EC 2.7.7.84 - 2'-5' oligoadenylate synthase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
2.7.7.84
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RECOMMENDED NAME
GeneOntology No.
2'-5' oligoadenylate synthase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
3 ATP = pppA2'p5'A2'p5'A + 2 diphosphate
show the reaction diagram
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SYSTEMATIC NAME
IUBMB Comments
ATP:ATP adenylyltransferase (2'-5' linkages-forming)
The enzyme is activated by binding to double-stranded RNA. The resulting product binds to and activates RNase L, which subsequently degrades the RNA. Oligoadenylates of chain lengths 2, 4 and 5 are also produced. The dimer does not have any known biological activity [2].
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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Manually annotated by BRENDA team
freshwater sponge, collected in Lake Baikal (Russia) from an unpolluted, natural site near the village of Listvianka, gene LB2-5OAS
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Manually annotated by BRENDA team
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UniProt
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
evolution
malfunction
physiological function
additional information
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
2 ATP
pppA2'p5'A + diphosphate
show the reaction diagram
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synthesis of 2-5A dimer, trimer and tetramer with the prevalence of dimer among reaction products
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?
3 1,N6-ethenoadenosine
?
show the reaction diagram
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?
3 2-beta-D-ribofuranosylthiazole-4-carboxamide
?
show the reaction diagram
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?
3 2-chloroadenosine
?
show the reaction diagram
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?
3 3-ribosyladenine
?
show the reaction diagram
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?
3 8-azaadenosine
?
show the reaction diagram
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?
3 8-bromoadenosine
?
show the reaction diagram
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?
3 adenosine
?
show the reaction diagram
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?
3 adenosine 1-oxide
?
show the reaction diagram
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?
3 ATP
pppA2'p5'A2'p5'A + 2 diphosphate
show the reaction diagram
3 ATP
pppA2'p5'A3'p5'A + 2 diphosphate
show the reaction diagram
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enzyme synthesizes triadenylates with the first linkage being a 2',5'-phosphodiester bond and the second one being a 3',5'-bond. The ratio of products containing 2',5'-linkage to the products with 3',5'-linkage is 2.4 in the presence of 100 mg/ml poly(I)poly(C)
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?
3 CTP
?
show the reaction diagram
3 cytidine
?
show the reaction diagram
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?
3 dATP
?
show the reaction diagram
3 formycin
?
show the reaction diagram
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?
3 GTP
?
show the reaction diagram
3 guanosine
?
show the reaction diagram
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?
3 inosine
?
show the reaction diagram
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?
3 ribavirin
?
show the reaction diagram
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?
3 sangivamycin
?
show the reaction diagram
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?
3 toyocamycin
?
show the reaction diagram
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?
3 uridine
?
show the reaction diagram
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?
3 UTP
?
show the reaction diagram
dATP + NAD+
?
show the reaction diagram
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?
n ATP
pppA(2'p5'A)n + 2 diphosphate
show the reaction diagram
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reaction of OAS1
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?
NTP + pppA2'p5'A
pppA2'p5'Ap5'N + 2 diphosphate
show the reaction diagram
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reaction of OAS2, broad spectrum of accepted donor substrates, including ATP, GTP, CTP, UTP, ITP, and their deoxy variants, overview
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?
NTP + RpA
RpA2'p5'N + 2 diphosphate
show the reaction diagram
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reaction of OAS3, broad spectrum of accepted donor substrates, including ATP, GTP, CT, UTP, ITP, and their deoxy variants, and of acceptor substrates including tRNA, A5'ppp5''A, A5'pppp5''A, NAD+, and polyA, overview
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?
tubercidin
?
show the reaction diagram
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?
additional information
?
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
3 ATP
pppA2'p5'A2'p5'A + 2 diphosphate
show the reaction diagram
additional information
?
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Mn2+
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activates, can substitute for Mg2+
additional information
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the enzyme activity is not affected by Ca2+ ions
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
ATP
substrate inhibition at higher concentrations
Co2+
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moderate inhibition
Cu2+
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strong inhibition
Fe2+
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strong inhibition
Ni2+
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moderate inhibition
Zn2+
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strong inhibition, zinc ions can control the oligomerisation by enhancing the formation of tetrameric forms of OAS1p42
additional information
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
dsRNA
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viral dsRNA
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2'-5'-oligoadenylate synthases are activated by viral double-stranded RNA in infected cells and initiate a cellular response by synthesizing 2'-5'-oligoadenylates, which in turn activate RNase L. All mammalian OAS proteins require dsRNA for activity ssRNA or DNA does not activate this class of enzymes. The dsRNA activator must be at least 15 nucleotides long, and no modification of the 2'-hydroxyl group is tolerated. OAS1 RNA activation site structure, overview
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viral RNA VAI
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sequences and secondary structures of adenovirus VAI dsRNAs, overview. Highly structured RNA, VAI, positively regulates the activity of the interferon-induced 2'–5'-oligoadenylate synthase, which typically represents a key mechanism whereby host-cell protein translation is attenuated in response to foreign dsRNA. In the contrary, with other cell proteins, RNA VAI, after processing by the RNA silencing machinery, inhibits the innate immune response via a series of interactions with specific protein partners. OAS1:VAI complex stoichiometry and kinetics, overview. The RNA 5'-end phosphorylation state is important in the activation or inhibition of OAS enzymes. While full-length VAI does indeed activate OAS1 in vitro, the Dicer-truncated molecule lacking the terminal stem has the opposite effect, and this is the physiologically important response, overview
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.00044 - 0.0017
ATP
0.0011 - 0.0014
NAD+
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.95 - 8.1
ATP
0.99 - 3.6
NAD+
Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
additional information
additional information
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inhibition kinetics with Zn2+
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IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.021 - 0.099
Zn2+
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.0005
OAS1 mutant R38E/K41E/K59E/R194E/R198E, pH and temperature not specified in the publication
0.001
OAS1 mutant R194E/R198E, pH and temperature not specified in the publication
0.004
OAS1 mutant R198E, pH and temperature not specified in the publication
0.007
OAS1 mutant R198M, pH and temperature not specified in the publication
0.016
OAS1 mutant R38E/K41E, pH and temperature not specified in the publication
0.05
OAS1 mutant K203E, pH and temperature not specified in the publication
0.117
OAS1 mutant K59E, pH and temperature not specified in the publication
0.16
OAS1 mutant K41E, pH and temperature not specified in the publication
0.17
OAS1 mutant R194E, pH and temperature not specified in the publication
0.22
OAS1 mutant R38E, pH and temperature not specified in the publication
3.3
OAS1 mutant R245E/K246E, pH and temperature not specified in the publication
10.1
wild-type OAS1, pH and temperature not specified in the publication
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
6.6
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isozyme OAS2
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
30
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assay at
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
8.12
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sequence calculation
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
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cell line displays high enzymatic activity
Manually annotated by BRENDA team
OAS1 and OAS3 transcripts are constitutively expressed
Manually annotated by BRENDA team
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cutaneous T-cell lymphoma
Manually annotated by BRENDA team
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peripheral blood mononuclear cells from healthy persons, and obtained from cutaneous T-cell lymphomas
Manually annotated by BRENDA team
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no appreciable difference in 2',5'-oligoadenylate synthetase activity is found between T-cells and non-T-cells from cutaneous T-cell lymphomas, increased activity of 2'5'-oligoadenylate synthetase in PBMC from cutaneous T-cell lymphomas forming tetramer, pentamer, and hexamer products
Manually annotated by BRENDA team
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lymphoid cell of thymus, expression increases during inflammatory processes under ulcerogenic conditions caused by stress factors
Manually annotated by BRENDA team
additional information
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highest expression of the gene occurs in cells surrounding the aquiferous canals
Manually annotated by BRENDA team
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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association of this form of OAS with membranes of the nuclear envelope and the rough endoplasmic reticulum
Manually annotated by BRENDA team
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association of this form of OAS with membranes of the nuclear envelope and the rough endoplasmic reticulum
Manually annotated by BRENDA team
additional information
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three distinct forms of 2'-5'OAS exist in human cells, that show distinct subcellular localizations
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Manually annotated by BRENDA team
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
35000
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x * 35748, seuence calculation, x * 35000, SDS-PAGE
35748
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x * 35748, seuence calculation, x * 35000, SDS-PAGE
40000
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isozyme 2
42000
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x * 42000, OAS1, SDS-PAGE
43000
x * 43000, about, OAS1A, sequence calculation
110000
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isozyme 1
160000
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dimeric isozyme OAS2, gel filtration
180000
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tetrameric isozyme OAS1, gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
dimer
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2 * 56000-59000, isozyme OAS2, two dimers form a tetramer, SDS-PAGE
homotetramer
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4 * 56000-59000, isozyme OAS1, SDS-PAGE
tetramer
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trimer
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3 * 56000-59000, isozyme OAS3, SDS-PAGE
additional information
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
OAS1, X-ray diffraction structure determination and analysis
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OAS1, purified recombinant porcine OAS1, 1.5 mg/ml protein in 50 mM NaCl, 10 mM HEPES, pH 6.8, 0.5 mM EDTA, with 5 mM of iodoacetamide for 30 min at room temperature, then concentrated to 6 mg/ml for crystallization by vapor diffusion, best crystals grow at 20°C in 1:1 drops with a well solution of 30% PEG 2000 MME, 0.2 M ammonium sulfate, and 0.1 M sodium cacodylate at pH 6, X-ray diffraction structure determination and analysis at 2.2 A resolution, molecular replacement
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
recombinant myc- and His-tagged enzyme from Escherichhia coli by use of poly(I:C)-iron oxide nanoparticles
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recombinant tagged isozyme OAS1 from Escherichia coli, cleavage of the tag
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recombinant wild-type and mutant OAS1 from Escherichia coli strain BL21(DE3) by gel filtration, ammonium sulfate fractionation, heparin affinity chromatography and gel filtration
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression in transgenic Solanum tuberosum plants using the Agrobacterium tumefaciens transfection system, the transformed plants show increased resistance against potato virus X, virus concentration is much lower in leaves and tubers compared to wild-type plants, the virus concentrations are almost that low in transgenic plants expressing the potato virus X coat protein
expression of tagged isozyme OAS1 in Escherichia coli
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functional expression of p42 isoform of OAS1 and the p69 isoform of OAS2 in insect cells
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gene LB2-5OAS, DNA and amino acid sequence determination and analysis, phylogenetic analysis, expression of myc- and His-tagged enzyme in Escherichhia coli
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OAS1, expression of wild-type and mutant enzymes in Escherichia coli strain BL21(DE3)
stable Oas1b protein overexpression under the control of the Tet-Off expression system in a mouse fibroblastic cell line, MEF/3T3.Tet-Off. The murine cells respond to Oas1b expression by efficiently inhibiting WNV viral replication
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three distinct forms of 2'-5'OAS exist in human cells, small, medium, and large, which contain one, two, and three OAS units, respectively, and are encoded by distinct genes, clustering of the genes encoding OAS1, OAS2, OAS3 and OASL on human chromosome 12q24.2, genetic organization, expression of isozyme OAS3 and the two forms of OAS2 in HeLa cells, expression of recombinant OAS2 in insect cells
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
expression is significantly induced following interferon treatment
induction by interferon
induction of sponge (2-5)A synthetase in response to poly(I:C)
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the enzyme has to be induced, induction by NDV or phenylhydrazine enhances expression of different isozymes, overview
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
up
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induction by interferon
K203E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
K212A
the mutant has strongly impaired catalytic activity, KM for ATP is increased by almost 4fold relative to that of the wild-type protein, and kcat is decreased by roughly 8fold
K41E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
K59E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
R194E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
R194E/R198E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
R198E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
R198M
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
R245E/K246E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
R38E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
R38E/K41E
site-directed mutagenesis, the mutant shows reduced activity compared to the wild-type enzyme
R38E/K41E/K59E/R194E/R198E
site-directed mutagenesis, the mutant is almost inactive
S62A
the mutant displays a strong substrate inhibition at higher ATP concentrations, more dramatic than that observed for wild-type OAS1
S63A
the mutant displays a strong substrate inhibition at higher ATP concentrations, more dramatic than that observed for wild-type OAS1
additional information
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substitutions of amino acids in front of the P-loop of Lys42 and Lys60 as well as that of Arg195 reduce the 2'-5'OAS activity at least 50fold. Furthermore substitutions in the Lys199 and Lys204 reduce the activity more than a 1000fold
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
analysis
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modified coupled spectrophotometric assay to detect 2-5 oligoadenylate synthetase enzyme activity in prostate cell lines as a model system. The phosphates generated by the OAS enzymatic reaction are coupled with conversion of the substrate 2-amino-6-mercapto-7-methylpurine ribonucleoside to a purine base product, 2-amino-6-mercapto-7-methylpurine and ribose1-phosphate via a purine nucleoside phosphorylase
medicine