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5.1.3.23

Accepted name:

UDP-2,3-diacetamido-2,3-dideoxyglucuronic acid 2-epimerase

Reaction:

UDP-2,3-diacetamido-2,3-dideoxy-α-D-glucuronate = UDP-2,3-diacetamido-2,3-dideoxy-α-D-mannuronate

For diagram of UDP-2,3-diacetamido-2,3-dideoxy-D-mannuronate biosynthesis, click here

Glossary:

UDP-α-D-GlcNAc3NAcA = UDP-2,3-diacetamido-2,3-dideoxy-α-D-glucuronic acid
UDP-α-D-ManNAc3NAcA = UDP-2,3-diacetamido-2,3-dideoxy-α-D-mannuronic acid

Other name(s):

UDP-GlcNAc3NAcA 2-epimerase; UDP-α-D-GlcNAc3NAcA 2-epimerase; 2,3-diacetamido-2,3-dideoxy-α-D-glucuronic acid 2-epimerase; WbpI; WlbD

Systematic name:

2,3-diacetamido-2,3-dideoxy-α-D-glucuronate 2-epimerase

Comments:

This enzyme participates in the biosynthetic pathway for UDP-α-D-ManNAc3NAcA (UDP-2,3-diacetamido-2,3-dideoxy-α-D-mannuronic acid), an important precursor of the B-band lipopolysaccharide of Pseudomonas aeroginosa serotype O5 and of the band-A trisaccharide of Bordetella pertussis, both important respiratory pathogens [1]. The enzyme is highly specific as UDP-α-D-GlcNAc, UDP-α-D-GlcNAcA (UDP-2-acetamido-2-deoxy-α-D-glucuronic acid) and UDP-α-D-GlcNAc3NAc (UDP-2,3-diacetamido-2,3-dideoxy-α-D-glucose) cannot act as substrates [1].

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc

References:

1.	Westman, E.L., McNally, D.J., Rejzek, M., Miller, W.L., Kannathasan, V.S., Preston, A., Maskell, D.J., Field, R.A., Brisson, J.R. and Lam, J.S. Identification and biochemical characterization of two novel UDP-2,3-diacetamido-2,3-dideoxy-α-D-glucuronic acid 2-epimerases from respiratory pathogens. Biochem. J. 405 (2007) 123–130. [DOI] [PMID: 17346239]
2.	Westman, E.L., McNally, D.J., Rejzek, M., Miller, W.L., Kannathasan, V.S., Preston, A., Maskell, D.J., Field, R.A., Brisson, J.R. and Lam, J.S. Erratum report: Identification and biochemical characterization of two novel UDP-2,3-diacetamido-2,3-dideoxy-α-D-glucuronic acid 2-epimerases from respiratory pathogens. Biochem. J. 405 (2007) 625.
3.	Sri Kannathasan, V., Staines, A.G., Dong, C.J., Field, R.A., Preston, A.G., Maskell, D.J. and Naismith, J.H. Overexpression, purification, crystallization and data collection on the Bordetella pertussis wlbD gene product, a putative UDP-GlcNAc 2′-epimerase. Acta Crystallogr. D Biol. Crystallogr. 57 (2001) 1310–1312. [PMID: 11526328]

[EC 5.1.3.23 created 2007]

5.1.3.26

Accepted name:

N-acetyl-α-D-glucosaminyl-diphospho-ditrans,octacis-undecaprenol 4-epimerase

Reaction:

N-acetyl-α-D-glucosaminyl-diphospho-ditrans,octacis-undecaprenol = N-acetyl-α-D-galactosaminyl-diphospho-ditrans,octacis-undecaprenol

Other name(s):

GlcNAc-P-P-Und epimerase; GlcNAc-P-P-Und 4-epimerase; gne (gene name)

Systematic name:

N-acetyl-α-D-glucosaminyl-diphospho-ditrans,octacis-undecaprenol 4-epimerase

Comments:

The enzyme is involved in biosynthesis of the repeating tetrasaccharide unit of the O-antigen produced by some Gram-negative bacteria.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc

References:

1.	Rush, J.S., Alaimo, C., Robbiani, R., Wacker, M. and Waechter, C.J. A novel epimerase that converts GlcNAc-P-P-undecaprenol to GalNAc-P-P-undecaprenol in Escherichia coli O157. J. Biol. Chem. 285 (2010) 1671–1680. [DOI] [PMID: 19923219]

[EC 5.1.3.26 created 2013]

5.1.3.36

Accepted name:

heparosan-glucuronate 5-epimerase

Reaction:

[heparosan]-D-glucuronate = [acharan]-L-iduronate

Glossary:

acharan = [GlcNAc-α-(1→4)-IdoA-α-(1→4)]_n
heparosan = [GlcNAc-α-(1→4)-GlcA-β-(1→4)]_n

Other name(s):

HG-5epi

Systematic name:

[heparosan]-D-glucuronate 5-epimerase

Comments:

The enzyme, characterized from the giant African snail Achatina fulica, participates in the biosynthetic pathway of acharan sulfate. Unlike EC 5.1.3.17, heparosan-N-sulfate-glucuronate 5-epimerase, it shows no activity with D-glucuronate residues in heparosan-N-sulfate.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc

References:

1.	Mochizuki, H., Yamagishi, K., Suzuki, K., Kim, Y.S. and Kimata, K. Heparosan-glucuronate 5-epimerase: Molecular cloning and characterization of a novel enzyme. Glycobiology 25 (2015) 735–744. [DOI] [PMID: 25677302]

[EC 5.1.3.36 created 2015]

6.3.1.12

Accepted name:

D-aspartate ligase

Reaction:

ATP + D-aspartate + [β-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)]_n = [β-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-6-N-(β-D-Asp)-L-Lys-D-Ala-D-Ala)]_n + ADP + phosphate

For diagram of reaction, click here

Other name(s):

Asl_fm; UDP-MurNAc-pentapeptide:D-aspartate ligase; D-aspartic acid-activating enzyme

Systematic name:

D-aspartate:[β-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)]_n ligase (ADP-forming)

Comments:

This enzyme forms part of the peptidoglycan assembly pathway of Gram-positive bacteria grown in medium containing D-Asp. Normally, the side chains the acylate the 6-amino group of the L-lysine residue contain L-Ala-L-Ala but these amino acids are replaced by D-Asp when D-Asp is included in the medium. Hybrid chains containing L-Ala-D-Asp, L-Ala-L-Ala-D-Asp or D-Asp-L-Ala are not formed [4]. The enzyme belongs in the ATP-grasp protein superfamily [3,4]. The enzyme is highly specific for D-aspartate, as L-aspartate, D-glutamate, D-alanine, D-iso-asparagine and D-malic acid are not substrates [4]. In Enterococcus faecium, the substrate D-aspartate is produced by EC 5.1.1.13, aspartate racemase [4]

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc

References:

1.	Staudenbauer, W. and Strominger, J.L. Activation of D-aspartic acid for incorporation into peptidoglycan. J. Biol. Chem. 247 (1972) 5095–5102. [PMID: 4262567]
2.	Staudenbauer, W., Willoughby, E. and Strominger, J.L. Further studies of the D-aspartic acid-activating enzyme of Streptococcus faecalis and its attachment to the membrane. J. Biol. Chem. 247 (1972) 5289–5296. [PMID: 4626717]
3.	Galperin, M.Y. and Koonin, E.V. A diverse superfamily of enzymes with ATP-dependent carboxylate-amine/thiol ligase activity. Protein Sci. 6 (1997) 2639–2643. [DOI] [PMID: 9416615]
4.	Bellais, S., Arthur, M., Dubost, L., Hugonnet, J.E., Gutmann, L., van Heijenoort, J., Legrand, R., Brouard, J.P., Rice, L. and Mainardi, J.L. Asl_fm, the D-aspartate ligase responsible for the addition of D-aspartic acid onto the peptidoglycan precursor of Enterococcus faecium. J. Biol. Chem. 281 (2006) 11586–11594. [DOI] [PMID: 16510449]

[EC 6.3.1.12 created 2006]

6.3.5.13

Accepted name:

lipid II isoglutaminyl synthase (glutamine-hydrolysing)

Reaction:

ATP + β-D-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)-diphospho-ditrans,octacis-undecaprenol + L-glutamine + H₂O = ADP + phosphate + β-D-GlcNAc-(1→4)-MurNAc-L-Ala-D-isoglutaminyl-L-Lys-D-Ala-D-Ala-diphospho-ditrans,octacis-undecaprenol + L-glutamate (overall reaction)
(1a) L-glutamine + H₂O = L-glutamate + NH₃
(1b) ATP + β-D-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)-diphospho-ditrans,octacis-undecaprenol = ADP + β-D-GlcNAc-(1→4)-MurNAc-L-Ala-γ-D-O-P-Glu-L-Lys-D-Ala-D-Ala-diphospho-ditrans,octacis-undecaprenol
(1c) β-D-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-O-P-Glu-L-Lys-D-Ala-D-Ala)-diphospho-ditrans,octacis-undecaprenol + NH₃ = β-D-GlcNAc-(1→4)-MurNAc-L-Ala-D-isoglutaminyl-L-Lys-D-Ala-D-Ala-diphospho-ditrans,octacis-undecaprenol + phosphate

Glossary:

lipid II = undecaprenyldiphospho-N-acetyl-(N-acetylglucosaminyl)muramoyl peptide; the peptide element refers to L-alanyl-D-γ-glutamyl-L-lysyl/meso-2,6-diaminopimelyl-D-alanyl-D-alanine or a modified version thereof = undecaprenyldiphospho-4-O-(N-acetyl-β-D-glucosaminyl)-3-O-peptidyl-α-N-acetylmuramate; the peptide element refers to L-alanyl-D-γ-glutamyl-L-lysyl/meso-2,6-diaminopimelyl-D-alanyl-D-alanine or a modified version thereof

Other name(s):

MurT/GatD; MurT/GatD complex

Systematic name:

β-D-GlcNAc-(1→4)-Mur2Ac(oyl-L-Ala-γ-D-Glu-L-Lys-D-Ala-D-Ala)-diphospho-ditrans,octacis-undecaprenol:L-glutamine amidoligase (ADP-forming)

Comments:

The enzyme complex, found in Gram-positive bacteria, consists of two subunits. A glutaminase subunit (cf. EC 3.5.1.2, glutaminase) produces an ammonia molecule that is channeled to a ligase subunit, which adds it to the activated D-glutamate residue of lipid II, converting it to an isoglutamine residue.

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB

References:

1.	Munch, D., Roemer, T., Lee, S.H., Engeser, M., Sahl, H.G. and Schneider, T. Identification and in vitro analysis of the GatD/MurT enzyme-complex catalyzing lipid II amidation in Staphylococcus aureus. PLoS Pathog. 8:e1002509 (2012). [PMID: 22291598]
2.	Noldeke, E.R., Muckenfuss, L.M., Niemann, V., Muller, A., Stork, E., Zocher, G., Schneider, T. and Stehle, T. Structural basis of cell wall peptidoglycan amidation by the GatD/MurT complex of Staphylococcus aureus. Sci. Rep. 8:12953 (2018). [PMID: 30154570]
3.	Morlot, C., Straume, D., Peters, K., Hegnar, O.A., Simon, N., Villard, A.M., Contreras-Martel, C., Leisico, F., Breukink, E., Gravier-Pelletier, C., Le Corre, L., Vollmer, W., Pietrancosta, N., Havarstein, L.S. and Zapun, A. Structure of the essential peptidoglycan amidotransferase MurT/GatD complex from Streptococcus pneumoniae. Nat. Commun. 9:3180 (2018). [PMID: 30093673]

[EC 6.3.5.13 created 2019]