Information on EC 3.5.4.36 - mRNA(cytosine6666) deaminase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
3.5.4.36
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RECOMMENDED NAME
GeneOntology No.
mRNA(cytosine6666) deaminase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
cytosine6666 in apolipoprotein B mRNA + H2O = uracil6666 in apolipoprotein B mRNA + NH3
show the reaction diagram
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SYSTEMATIC NAME
IUBMB Comments
mRNA(cytosine6666) aminohydrolase
The apolipoprotein B mRNA editing enzyme complex catalyses the editing of apolipoprotein B mRNA at cytidine6666 to uridine, thereby transforming the codon for glutamine-2153 to a termination codon. Editing results in translation of a truncated apolipoprotein B isoform (apoB-48) with distinct functions in lipid transport. The catalytic component (APOBEC-1) contains zinc at the active site [3].
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
physiological function
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
5-methylcytosine in single-stranded DNA + H2O
thymine in single-stranded DNA + NH3
show the reaction diagram
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Apobec1 has 5-methylcytosine deaminase activity, resulting in a thymine base opposite a guanine. If this mismatch is repaired, a methylated cytosine is replaced by an unmethylated one. If it is not repaired, it results in a cytosine -> thymine transition mutation. Apobec1, and perhaps other members of this protein family play a role in epigenetic reprogramming
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?
cytosine in RNA + H2O
uracil in RNA + NH3
show the reaction diagram
cytosine in single-stranded DNA + H2O
uracil in single-stranded DNA + NH3
show the reaction diagram
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
show the reaction diagram
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
5-methylcytosine in single-stranded DNA + H2O
thymine in single-stranded DNA + NH3
show the reaction diagram
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Apobec1 has 5-methylcytosine deaminase activity, resulting in a thymine base opposite a guanine. If this mismatch is repaired, a methylated cytosine is replaced by an unmethylated one. If it is not repaired, it results in a cytosine -> thymine transition mutation. Apobec1, and perhaps other members of this protein family play a role in epigenetic reprogramming
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-
?
cytosine in RNA + H2O
uracil in RNA + NH3
show the reaction diagram
cytosine in single-stranded DNA + H2O
uracil in single-stranded DNA + NH3
show the reaction diagram
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murine APOBEC1 is a hypermutator of both RNA and ssDNA in vivo
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?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
show the reaction diagram
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
NaCl
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optimal activity of APOBEC1 without auxiliary factor at 80 mM ionic strength, optimal activity of APOBEC1 in presence of the auxiliary factor ACF at 90 mM
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
1,10-phenanthroline
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additional information
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1,7-phenanthroline has no effect
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
APOBEC1 complementation factor
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.000000017 - 0.00000022
cytosine6666 in apolipoprotein B mRNA
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
7
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APOBEC1 in presence of the auxiliary factor ACF
7.4
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assay at
7.5
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APOBEC1 without auxiliary factor
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
30
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APOBEC1 in presence of the auxiliary factor ACF
45
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APOBEC1 without auxiliary factor
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
27277
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x * 27277, calculated from sequence
27280
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calculated from sequence
28000
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calculated from nucleotide sequence
28192
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x * 28192, APOBEC-1 from human has proven difficult to purify at levels sufficient for structural studies. Cytosine deaminase from Saccharomyces cerevisiae (CDD1) can be purified readily, which is relevant due to its orthology with APOBEC-1 at the level of both cytidine deaminase (CDA) sequence similarity (27%) and mRNA-editing activity on apolipoprotein B (apoB) substrates. Crystal structure of ScCDD1 is determined to 2.0 A resolution, which reveals that the fundamental CDA fold is necessary and sufficient for C-to-U deamination in pyrimidine metabolism, as well as RNA editing. The data from the CDD1 structure provide the basis for comparative modeling of the APOBEC-1 structure
46000
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x * 46000, SDS-PAGE
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
characterization of the APOBEC-1 gene and an unusual aberrant splicing pattern of the pre-mRNA
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expressed in Escherichia coli, as a glutathione S-transferase fusion protein. Overexpression of wild-type apobec-1 in McA 7777 cells results in a 5-6-fold increase in editing of endogenous apoB
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expression in COS-7 cells
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expression in Escherichia coli
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expression in Escherichia coli or in Sf9 cells
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expression in Escherichia coli, the opossum APOBEC-1 gene has the same intron/exon organisation in the coding sequence as the eutherian gene
expression of the catalytic subunit of the editing enzyme, p27, in McArdle 7777 cells and in in COS cells. Transfected COS and CHO cells express p27 but lack additional proteins that are required for editing
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high level expression of APOBEC1 in Sf9 cells as an N-terminal GST fusion protein. Substantial RNA editing activity of APOBEC1 alone may be responsible for the hyperediting observed upon overexpression of APOBEC1 in transgenic mice. These animals develop hepatocellular carcinomas
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when the catalytic subunit of the editing enzyme, p27, is expressed in Xenopus oocytes, it requires other proteins to edit apoB mRNA in vitro
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
C96A
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mutation abolishes editing and zinc binding
E63A
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inactive
F66L
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mutation abolishes editing activity
F70L
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mutation has no effect on editing activity
F76L
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mutation has no effect on editing activity
F87L
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mutation abolishes editing activity
V64L
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mutation has no effect on activity
C93A
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the mutant retains 4% of wild-type editing activity
C96A
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mutant lacks activity
E63Q
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inactive mutant enzyme. The ability of the mutant proteins to restrict the infectivity of wild-type and DELTAvif viruses are severely, but not completely impaired
H61A
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mutant lacks activity
H61C
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mutant shows 80% of wild-type editing activity
P92A
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the mutant retains 18% of wild-type editing activity
V62A
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the mutant retains 89% of wild-type editing activity
C93S
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loss of RNA editing activity, great reduction of cytidine deaminase activity
E63Q
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wild-type levels of RNA binding, mutation abolishes both cytidine deaminase and RNA editing activity
H61C
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mutation retains both editing and cytidine deaminase activity
additional information