Information on EC 2.4.1.184 - galactolipid galactosyltransferase

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The expected taxonomic range for this enzyme is: Eukaryota, Bacteria

EC NUMBER
COMMENTARY
2.4.1.184
-
RECOMMENDED NAME
GeneOntology No.
galactolipid galactosyltransferase
REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
2 a 1,2-diacyl-3-O-(beta-D-galactosyl)-sn-glycerol = a 1,2-diacyl-3-O-[alpha-D-galactosyl-(1->6)-beta-D-galactosyl]-sn-glycerol + a 1,2-diacyl-sn-glycerol
show the reaction diagram
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-
-
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REACTION TYPE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
hexosyl group transfer
-
-
-
-
PATHWAY
KEGG Link
MetaCyc Link
Glycerolipid metabolism
-
glycolipid biosynthesis
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Metabolic pathways
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SYSTEMATIC NAME
IUBMB Comments
3-(beta-D-galactosyl)-1,2-diacyl-sn-glycerol:3-(beta-D-galactosyl)-1,2-diacyl-sn-glycerol beta-D-galactosyltransferase
By further transfers of galactosyl residues to the digalactosyldiacylglycerol, trigalactosyldiacylglycerol and tetragalactosyldiacylglycerol are also formed. This enzyme was originally thought to be the major enzyme involved in the production of digalactosyldiacylglycerol in plants as it masked the effect of the true enzyme (EC 2.4.1.241, digalactosyldiacylglycerol synthase) [4,5]. Its activity is localized to chloroplast envelope membranes, but it does not contribute to net galactolipid synthesis in plants [4].
SYNONYMS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
beta-GalT
-
beta-galactosyltransferase
galactolipid:galactolipid galactosyltransferase
-
-
-
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galactosyltransferase, galactolipid-galactolipid
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-
-
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GGGT
-
-
-
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interlipid galactosyltransferase
-
-
-
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mono-beta-D-galactosyldiacylglycerol:mono-beta-D-galactosyldiacylglycerol beta-D-galactosyltransferase
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-
-
-
tRNA (guanosine-2'-O-)-methyltransferase
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-
-
-
CAS REGISTRY NUMBER
COMMENTARY
66676-74-2
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ORGANISM
COMMENTARY
LITERATURE
SEQUENCE CODE
SEQUENCE DB
SOURCE
isoforms Dgd2, dgd1
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-
Manually annotated by BRENDA team
under normal growth conditions, the in vivo activity of the galactolipid:galactolipid galactosyltransferase is not detectable in the wild type, but becomes apparent in the tgd mutant. The enzyme does not provide the bulk of glactoglycerolipids in the chloroplast, but is speculated to play a role during ozone-induced injury or possibly during senescence of leaves when chloroplast membranes are turned over
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-
Manually annotated by BRENDA team
in the lipid extract form cells expressing chlo02003782 monogalactosyldiacylglycerol is detected, therefor, this open reading frame is assigned as a beta-galactosyltransferase
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-
Manually annotated by BRENDA team
cv. New Asia
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-
Manually annotated by BRENDA team
SUBSTRATE
PRODUCT                      
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
mono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosyldiacylglycerol
alpha-D-galactosyl-beta-D-galactosyldiacylglycerol + diacylglycerol
show the reaction diagram
-
-
-
-
mono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosyldiacylglycerol
alpha-D-galactosyl-beta-D-galactosyldiacylglycerol + diacylglycerol
show the reaction diagram
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-
-
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mono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosyldiacylglycerol
alpha-D-galactosyl-beta-D-galactosyldiacylglycerol + diacylglycerol
show the reaction diagram
-
-
-
-
?
mono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosyldiacylglycerol
alpha-D-galactosyl-beta-D-galactosyldiacylglycerol + diacylglycerol
show the reaction diagram
-
-
-
r
mono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosyldiacylglycerol
alpha-D-galactosyl-beta-D-galactosyldiacylglycerol + diacylglycerol
show the reaction diagram
-
-
by further transfer of galactosyl residues to the digalactosyldiacylglycerol, trigalactosyldiacylglycerol and tetragalactosyldiacylglycerol are also formed
-
mono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosyldiacylglycerol
alpha-D-galactosyl-beta-D-galactosyldiacylglycerol + diacylglycerol
show the reaction diagram
-
-
by further transfer of galactosyl residues to the digalactosyldiacylglycerol, trigalactosyldiacylglycerol and tetragalactosyldiacylglycerol are also formed
-
mono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosyldiacylglycerol
alpha-D-galactosyl-beta-D-galactosyldiacylglycerol + diacylglycerol
show the reaction diagram
-
digalactosyldiacylglycerol synthesis proceeds most rapidly by galactosyl transfer to hexaene species of monogalactosyldiacylglycerol
by further transfer of galactosyl residues to the digalactosyldiacylglycerol, trigalactosyldiacylglycerol and tetragalactosyldiacylglycerol are also formed
-
additional information
?
-
-
enzyme isoform Dgd2 is crucial for synthesis of additional digalactosyldiacylglycerol during phosphate deprivation
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-
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
mono-beta-D-galactosyldiacylglycerol + mono-beta-D-galactosyldiacylglycerol
alpha-D-galactosyl-beta-D-galactosyldiacylglycerol + diacylglycerol
show the reaction diagram
-
-
-
-
?
additional information
?
-
-
enzyme isoform Dgd2 is crucial for synthesis of additional digalactosyldiacylglycerol during phosphate deprivation
-
-
-
METALS and IONS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
Ba2+
-
10 mM, 23fold stimulation
Ca2+
-
10 mM, 23fold stimulation
Ca2+
-
alpha-linolenic acid stimulates activity in presence of CaCl2
Co2+
-
10 mM, 3fold simulation
Fe2+
-
10 mM, 6fold simulation
K+
-
50 mM, weak stimulation
K+
-
50 mM, 5fold stimulation
K+
-
alpha-linolenic acid stimulates in presence of high concentrations of KCl
Li+
-
50 mM, weak stimulation
Mg2+
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EDTA inhibits stimulation
Mg2+
-
10 mM, 20fold stimulation
Mg2+
-
stimulates forward reaction, no effect on reverse reaction
Mg2+
-
alpha-linolenic acid causes drastic increase in activity under limiting concentrations of MgCl2, without affecting its maximum activity at higher MgCl2 concentration, free alpha-linolenic acid alone does not affect the activity; EDTA inhibits stimulation; unsaturated 16- and 18-carbon fatty acids stimulate in presence of MgCl2
Mn2+
-
10 mM, 23fold stimulation
Mn2+
-
alpha-linolenic acid stimulates activity in presence of MnCl2
Na+
-
50 mM, weak stimulation
INHIBITORS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
CdCl2
-
2 mM, 50% inhibition
N-ethylmaleimide
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-
p-hydroxymercuribenzoate
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-
Thermolysin
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-
-
UDP
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8 mM, 50% inhibition
UMP
-
10 mM, 50% inhibition
Zn2+
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2 mM, complete inhibition
Zn2+
-
1 mM, 75% inhibition
ACTIVATING COMPOUND
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
alpha-linolenic acid
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0.3 mM, 28fold stimulation in the presence of 2 mM MgCl2, MgCl2 can be replaced by MnCl2, CaCl2 or high concetrations of KCl
hexadecatrienoic acid
-
approx. 3fold activation
NH4+
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50 mM, 5fold stimulation
oleic acid
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approx. 4fold activiation
palmitic acid
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approx. 2fold activiation
palmitoleic acid
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approx. 4fold activiation
stearic acid
-
approx. 2fold activiation
linoleic acid
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approx. 4fold activiation
additional information
-
activated by free fatty acids in the presence of divalent cations such as Mg2+ following ozone fumigation
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pH OPTIMUM
pH MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
6
7
-
forward reaction
6.5
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-
reverse reaction
8
-
-
assay at
pH RANGE
pH RANGE MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
4.7
8.9
-
approx. 50% of maximal activity at pH 5.3 and pH 8.0
TEMPERATURE OPTIMUM
TEMPERATURE OPTIMUM MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
30
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assay at
TEMPERATURE RANGE
TEMPERATURE MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
4
30
-
still active at 4°C
SOURCE TISSUE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
SOURCE
LOCALIZATION
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
-
outer side of envolepe membrane, Dgd2, plus a third enzymic activity
Manually annotated by BRENDA team
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outer envelope membrane; outer surface of
Manually annotated by BRENDA team
-
envelope; outer envelope membrane
Manually annotated by BRENDA team
additional information
-
sensitivity to thermolysin suggests that the enzyme is located on the outside of the outer envelope of the chloroplast
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Manually annotated by BRENDA team
Cloned/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
expressed in Synechococcus cerevisiae
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ENGINEERING
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
additional information
-
analysis of dgd1 and dgd2 double mutants show that galactolipid:galactolipid galactosyltransferase is different from the genuine digalactosyldiacylglycerol synthases DGD1 and DGD2, because chloroplasts of a double mutant still are capable of oligogalactolipid biosynthesis.; analysis of tgd mutants show that the galactosyl residues are all beta1->6-linked.
additional information
-
dgd2 null mutant, no effects on growth and lipid composition. Dgd1 dgd2 double null mutant, only trace amounts of digalactosyldiacylglycerol, but some monogalactosyldiacylglycerol and unusual oligogalactolipids like tri- and tetragalactosyldiacylglycerol