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GDP-D-mannose:D-Man-alpha-(1->3)-D-Man-beta-(1-4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol alpha-6-mannosyltransferase
The biosynthesis of asparagine-linked glycoproteins utilizes a dolichyl diphosphate-linked glycosyl donor, which is assembled by the series of membrane-bound glycosyltransferases that comprise the dolichol pathway. Alg2 mannosyltransferase from Saccharomyces cerevisiae carries out an alpha1,3-mannosylation (cf. EC 2.4.1.132) of beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol, followed by an alpha1,6-mannosylation, to form the first branched pentasaccharide intermediate of the dolichol pathway [1,2].
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2 GDP-alpha-D-mannose + beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-GlcNAc-PP-phytanyl
2 GDP + alpha-D-Man-(1->3)[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-PP-phytanyl
Substrates: synthesis of acceptor phytanyl oligosaccharide, Man1Gn2-PPhy, from beta-D-GlcNAc-(1->4)-GlcNAc-PP-phytanyl (Gn2-PPhy) using yeast Alg1. Recombinant scAlg2 transfers 2 Man residues to the beta1,4-Man of the Man1Gn2-PPhy substrate with alpha1,6 and alpha1,3-linkages, yielding alpha-D-Man-(1->3)[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-PP-phytanyl
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GDP-alpha-D-mannose + alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP + alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP-alpha-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP + D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
additional information
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GDP-alpha-D-mannose + alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP + alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
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GDP-alpha-D-mannose + alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP + alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
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GDP-alpha-D-mannose + alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP + alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
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GDP-alpha-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP + D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
Substrates: in eukaryotes, biosynthesis of N-glycans starts with the assembly of the common core oligosaccharide precursor Glc3Man9 GlcNAc2-PP-Dol, the glycan moiety of which is subsequently transferred onto selected Asn-Xaa-(Ser/Thr) acceptor sites of the nascent polypeptide chain by the oligosaccharyl-transferase complex
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GDP-alpha-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP + D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
Substrates: the biosynthesis of asparagine-linked glycoproteins utilizes a dolichylpyrophosphate-linked glycosyl donor, which is assembled by the series of membrane-bound glycosyltransferases that comprise the dolichol pathway. Alg2 carries out an alpha1,3-mannosylation of D-Man-beta-(1-4)-D-GlcNAc-beta-(1-4)-D-GlcNAc-diphosphodolichol, followed by an alpha1,6-mannosylation, to form the first branched pentasaccharide intermediate of the dolichol pathway
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GDP-alpha-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP + D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
Substrates: Alg2 carries out an alpha1,3-mannosylation of D-Man-beta-(1-4)-D-GlcNAc-beta-(1-4)-D-GlcNAc-diphosphodolichol, followed by an alpha1,6-mannosylation, to form the first branched pentasaccharide intermediate of the dolichol pathway
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GDP-alpha-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP + D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
Substrates: Alg2 is able to catalyze both the addition of the alpha1,3- and alpha1,6-linked mannose residue to Man1GlcNAc2-PP-Dol, forming Man2GlcNAc2-PP-Dol (cf. EC 2.4.1.132) and subsequently to Man3GlcNAc2-PP-Dol
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additional information
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Substrates: chemo-enzymatic synthesis of lipid-linked GlcNAc2Man5 oligosaccharides using recombinant Alg1, Alg2 and Alg11 proteins. Comparison to the reaction of dolichyl-diphosphooligosaccharide-protein glycosyltransferase subunit STT3A (EC 2.4.99.18)
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additional information
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Substrates: Alg2 shows no activity with D-Man-beta-(1-4)-D-GlcNAc-beta-(1-4)-D-GlcNAc-diphosphodolichol
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additional information
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Substrates: unique bifunctionality of Alg2 during lipid-linked oligosaccharide (LLO) synthesis
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additional information
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Substrates: unique bifunctionality of Alg2 during lipid-linked oligosaccharide (LLO) synthesis
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GDP-alpha-D-mannose + alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP + alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP-alpha-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP + D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP-alpha-D-mannose + alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP + alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
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GDP-alpha-D-mannose + alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP + alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
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GDP-alpha-D-mannose + alpha-D-Man-(1->3)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
GDP + alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-alpha-D-GlcNAc-diphosphodolichol
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GDP-alpha-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP + D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
Substrates: in eukaryotes, biosynthesis of N-glycans starts with the assembly of the common core oligosaccharide precursor Glc3Man9 GlcNAc2-PP-Dol, the glycan moiety of which is subsequently transferred onto selected Asn-Xaa-(Ser/Thr) acceptor sites of the nascent polypeptide chain by the oligosaccharyl-transferase complex
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GDP-alpha-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
GDP + D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol
Substrates: the biosynthesis of asparagine-linked glycoproteins utilizes a dolichylpyrophosphate-linked glycosyl donor, which is assembled by the series of membrane-bound glycosyltransferases that comprise the dolichol pathway. Alg2 carries out an alpha1,3-mannosylation of D-Man-beta-(1-4)-D-GlcNAc-beta-(1-4)-D-GlcNAc-diphosphodolichol, followed by an alpha1,6-mannosylation, to form the first branched pentasaccharide intermediate of the dolichol pathway
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malfunction
cells deleted for ALG2 are inviable. Mutant alg2 alleles display intraallelic complementation
metabolism
the fourth and fifth steps of lipid-linked oligosaccharide (LLO) synthesis are catalyzed by Alg2, an unusual mannosyltransferase (MTase) with two different MTase activities
additional information
the conserved C-terminal EX7E motif, N-terminal cytosolic tail, and 3G-rich loop motifs in Alg2 play crucial roles for these activities, both in vitro and in vivo. Alg2 immunoprecipitates from extracts of yeast microsomal membranes also displays both alpha1,3- and alpha1,6-mannosyltransferase (MTase) activities. The conserved Val62 residue is required for yeast Alg2 function. The first E (E335) and His-336 are partially required for alpha1,6-mannosylation, and importance of both E335 and E343 of the EX7E domain for Alg2 function in vivo. Identification of three conserved G-rich motifs in scAlg2, located in the N-terminal cytosolic short tail, in the middle of Alg2, and in the C-terminal domain. Residues G17, G19, and G20 are within the N-terminal cytosolic tail of Alg2, importance of this domain for Alg2 function
physiological function
asparagine (N)-linked glycosylation requires the ordered, stepwise synthesis of lipid-linked oligosaccharide (LLO) precursor Glc3Man9GlcNAc2-diphosphate-dolichol (Glc3Man9Gn2-PDol) on the endoplasmic reticulum. The fourth and fifth steps of LLO synthesis are catalyzed by Alg2, an unusual mannosyltransferase (MTase) with two different MTase activities. Alg2 adds both an alpha1,3- and alpha1,6-mannose onto ManGlcNAc2-PDol to form the trimannosyl core Man3GlcNAc2-PDol. Alg2-dependent Man3GlcNAc2-PDol production relies on net-neutral lipids with a propensity to form bilayers
physiological function
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asparagine (N)-linked glycosylation requires the ordered, stepwise synthesis of lipid-linked oligosaccharide (LLO) precursor Glc3Man9GlcNAc2-diphosphate-dolichol (Glc3Man9Gn2-PDol) on the endoplasmic reticulum. The fourth and fifth steps of LLO synthesis are catalyzed by Alg2, an unusual mannosyltransferase (MTase) with two different MTase activities. Alg2 adds both an alpha1,3- and alpha1,6-mannose onto ManGlcNAc2-PDol to form the trimannosyl core Man3GlcNAc2-PDol. Alg2-dependent Man3GlcNAc2-PDol production relies on net-neutral lipids with a propensity to form bilayers
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D203A
mutation has no influence on Alg2 function
D248A
mutation has no influence on Alg2 function
E264A
mutation has no influence on Alg2 function
E335A/E343A
significant lower level of product formation, identical to that of the E335A mutant
F337A
site-directed mutagenesis, Trx-scAlg2F337A produces 26% Man3Gn2 product compared to wild-type enzyme
G337A
mutation has no influence on Alg2 function
G337E
nonfunctional enzyme variant
G337R
nonfunctional enzyme variant
G338A
mutation has no influence on Alg2 function
G377R
site-directed mutagenesis, a temperature-sensitive alg2-1 mutant containing a single missense mutation, catalytically inactive
K206A
mutation has no influence on Alg2 function
K210A
mutation has no influence on Alg2 function
K229A
mutation has no effect on growth and glycosylation
K230A
mutation causes loss of Alg2 activity
K251A
mutation has no influence on Alg2 function
N231A
mutation has no effect on growth and glycosylation
N392A
mutation has no influence on Alg2 function
P192A
mutation has no influence on Alg2 function
P359A
mutation has no influence on Alg2 function
V62G
site-directed mutagenesis, Trx-scAlg2V62G produces 25% Man3Gn2 product compared to wild-type enzyme. The HA-tagged mutant allele (3HAscAlg2V62G) fails to complement the lethality of the alg2DELTA LSY2 when grown on 5-FOA
E335A
mutant has some residual activity
E335A
significant lower level of product formation
E335A
site-directed mutagenesis, Trx-scAlg2E335A produces only no final product and only 32% of intermediate Man2Gn2 compared to wild-type enzyme
E343A
no activity
E343A
inactive mutant enzyme
E343A
site-directed mutagenesis, inactive mutant
H336A
mutation has no influence on Alg2 function
H336A
site-directed mutagenesis, Trx-scAlg2H336A produces 8% Man3Gn2 product compared to wild-type enzyme
additional information
chemo-enzymatic synthesis of lipid-linked GlcNAc2Man5 oligosaccharides using recombinant Alg1 (from yeast, EC 2.4.1.142), Alg2, and Alg11 (from yeast, EC 2.4.1.131) proteins, chemo-enzymatic synthesis strategy to extend the glycan moiety of synthetic LLO analogues to Dol-PP-GlcNAc2Man5, method, overview
additional information
mutational analysis of Alg2 and identification of amino acids required for its activity. None of the four domains (predicted as transmembrane-spanning helices) is essential for transferase activity because truncated Alg2 variants can exert their function as long as Alg2 is associated with the endaplasmic reticulum by either its N- or C-terminal hydrophobic regions
additional information
site-directed mutagenesis of conserved EX7E motif. Trx-scAlg2E335A, mutated in the first E, has significantly decreased activity, producing no final product and only 32% of intermediate Man2Gn2. Trx-scAlg2E343A, mutated in the second E, has no detectable activity. The intervening amino acids of the EX7E are also important, though less than either E335 or E343. Trx-scAlg2H336A and Trx-scAlg2F337A produce 8% and 26% of Man3Gn2 product, respectively, compared to wild-type. Cells deleted for ALG2 are inviable, a plasmid shuffling technique is used to measure complementation. Mutant alg2 alleles display intraallelic complementation. Mutations (changed to proline) in five of the glycines (G19, G20, G256, G357, G358) result in complete loss of activity, while two of them (G17, G257) are significantly decreased
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Gao, X.D.; Nishikawa, A.; Dean, N.
Physical interactions between the Alg1, Alg2, and Alg11 mannosyltransferases of the endoplasmic reticulum
Glycobiology
14
559-570
2004
Saccharomyces cerevisiae
brenda
O'Reilly, M.K.; Zhang, G.; Imperiali, B.
In vitro evidence for the dual function of Alg2 and Alg11: essential mannosyltransferases in N-linked glycoprotein biosynthesis
Biochemistry
45
9593-9603
2006
Saccharomyces cerevisiae (P43636)
brenda
Kämpf, M.; Absmanner, B.; Schwarz, M.; Lehle, L.
Biochemical characterization and membrane topology of Alg2 from Saccharomyces cerevisiae as a bifunctional alpha1,3- and 1,6-mannosyltransferase involved in lipid-linked oligosaccharide biosynthesis
J. Biol. Chem.
284
11900-11912
2009
Saccharomyces cerevisiae (P43636)
brenda
Valderrama-Rincon, J.D.; Fisher, A.C.; Merritt, J.H.; Fan, Y.Y.; Reading, C.A.; Chhiba, K.; Heiss, C.; Azadi, P.; Aebi, M.; DeLisa, M.P.
An engineered eukaryotic protein glycosylation pathway in Escherichia coli
Nat. Chem. Biol.
8
434-436
2012
Saccharomyces cerevisiae
brenda
Li, S.-T.; Wang, N.; Xu, X.-X.; Fujita, M.; Nakanishi, H.; Kitajima, T.; Dean, N.; Gao, X.-D.
Alternative routes for synthesis of N-linked glycans by Alg2 mannosyltransferase
FASEB J.
32
2492-2506
2018
Saccharomyces cerevisiae (P43636), Saccharomyces cerevisiae ATCC 204508 (P43636)
brenda
Ramirez, A.S.; Boilevin, J.; Lin, C.W.; Ha Gan, B.; Janser, D.; Aebi, M.; Darbre, T.; Reymond, J.L.; Locher, K.P.
Chemo-enzymatic synthesis of lipid-linked GlcNAc2Man5 oligosaccharides using recombinant Alg1, Alg2 and Alg11 proteins
Glycobiology
27
726-733
2017
Homo sapiens (Q9H553)
brenda