Glycosyltransferase Family 38

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• Author: ^^^Warren Wakarchuk^^^
• Responsible Curator: ^^^Warren Wakarchuk^^^

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Glycosyltransferase Family GT38
Clan	GT-B
Mechanisn	inverting
Active site residues	known
CAZy DB link
http://www.cazy.org/GT38.html

Substrate specificities

Members of GT-38 are the bacterial polysialyltransferases (polySTs), which catalyze the addition of sialic acids from the activated sugar donor, CMP-sialic acid (CMP-Neu5Ac), to the nonreducing end of the growing polySia chain [1]. These enzymes build the polymer as a capsular polysaccharide on a specialized poly-β-KDO modified lyso-phosphatidyl glycerol anchor in the membrane of Gram negative bacteria [2]. Bacterial polySia capsules exist in three different flavours: Escherichia coli K1, Neisseria meningitidis serotype B, Moraxella nonliquefaciens, and Mannheimia haemolytica A2 synthesize α-2,8-linked polySia whereas N. meningitidis serotype C produces a α-2,9-linked polymer and E. coli K92 produces polymers with alternating α-2,8 and α-2,9 linkages [3][4][5]. In vitro enzyme reactions have shown that the members of GT-38 require two sialic acids for elongation [6][7], presumably as this mimics the in vivo lipid primer. The molecular mimicry of these bacterial polySia capsules represents an elegant strategy to evade the host’s immune recognition since they are not considered as foreign. In addition, they confer a physical barrier protecting the pathogen from killing by the complement system [8].

Kinetics and Mechanism

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Catalytic Residues

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Three-dimensional structures

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Family Firsts

First stereochemistry determination

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First catalytic nucleophile identification

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First general acid/base residue identification

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First 3-D structure

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References

1. Cho JW and Troy FA 2nd. (1994). Polysialic acid engineering: synthesis of polysialylated neoglycosphingolipids by using the polysialyltransferase from neuroinvasive Escherichia coli K1. Proc Natl Acad Sci U S A. 1994;91(24):11427-31. DOI:10.1073/pnas.91.24.11427 |
2. Willis LM, Stupak J, Richards MR, Lowary TL, Li J, and Whitfield C. (2013). Conserved glycolipid termini in capsular polysaccharides synthesized by ATP-binding cassette transporter-dependent pathways in Gram-negative pathogens. Proc Natl Acad Sci U S A. 2013;110(19):7868-73. DOI:10.1073/pnas.1222317110 |
2. Willis LM, Stupak J, Richards MR, Lowary TL, Li J, and Whitfield C. (2013). Conserved glycolipid termini in capsular polysaccharides synthesized by ATP-binding cassette transporter-dependent pathways in Gram-negative pathogens. Proc Natl Acad Sci U S A. 2013;110(19):7868-73. DOI:10.1073/pnas.1222317110 |
3. Puente-Polledo L, Reglero A, González-Clemente C, Rodríguez-Aparicio LB, and Ferrero MA. (1998). Biochemical conditions for the production of polysialic acid by Pasteurella haemolytica A2. Glycoconj J. 1998;15(9):855-61. DOI:10.1023/a:1006902931032 |
4. Devi SJ, Schneerson R, Egan W, Vann WF, Robbins JB, and Shiloach J. (1991). Identity between polysaccharide antigens of Moraxella nonliquefaciens, group B Neisseria meningitidis, and Escherichia coli K1 (non-O acetylated). Infect Immun. 1991;59(2):732-6. DOI:10.1128/iai.59.2.732-736.1991 |
5. Glode MP, Robbins JB, Liu TY, Gotschlich EC, Orskov I, and Orskov F. (1977). Cross-antigenicity and immunogenicity between capsular polysaccharides of group C Neisseria meningitidis and of Escherichia coli K92. J Infect Dis. 1977;135(1):94-104. DOI:10.1093/infdis/135.1.94 |
6. Willis LM, Gilbert M, Karwaski MF, Blanchard MC, and Wakarchuk WW. (2008). Characterization of the alpha-2,8-polysialyltransferase from Neisseria meningitidis with synthetic acceptors, and the development of a self-priming polysialyltransferase fusion enzyme. Glycobiology. 2008;18(2):177-86. DOI:10.1093/glycob/cwm126 |
7. Lindhout T, Bainbridge CR, Costain WJ, Gilbert M, and Wakarchuk WW. (2013). Biochemical characterization of a polysialyltransferase from Mannheimia haemolytica A2 and comparison to other bacterial polysialyltransferases. PLoS One. 2013;8(7):e69888. DOI:10.1371/journal.pone.0069888 |

8. pmid= 8884739

9. Wheeler DC, Smith B, and Walls J. (1986). Substitution of aluminium salts by magnesium salts in control of dialysis hyperphosphataemia. Lancet. 1986;1(8494):1380. DOI:10.1016/s0140-6736(86)91687-9 |