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Difference between revisions of "Glycosyltransferase Family 38"

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== Substrate specificities ==
 
== Substrate specificities ==
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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 (PMID: 7972078 Cho and Troy 1994; Nakayama and Fukuda 1996). 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 PMID: 23610430. 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 PMID: 10052589 PMID: 1898915 PMID: 64575.  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 PMID: 8884739.
 
 
Authors may get an idea of what to put in each field from ''Curator Approved'' [[Glycosyltransferase Families]]. ''(TIP: Right click with your mouse and open this link in a new browser window...)''
 
 
 
In the meantime, please see these references for an essential introduction to the CAZy classification system: <cite>DaviesSinnott2008 Cantarel2009</cite>.
 
  
 
== Kinetics and Mechanism ==
 
== Kinetics and Mechanism ==

Revision as of 08:43, 27 May 2020

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Glycosyltransferase Family GT38
Clan GH-x
Mechanism retaining/inverting
Active site residues known/not known
CAZy DB link
https://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 (PMID: 7972078 Cho and Troy 1994; Nakayama and Fukuda 1996). 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 PMID: 23610430. 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 PMID: 10052589 PMID: 1898915 PMID: 64575. 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 PMID: 8884739.

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. Cantarel BL, Coutinho PM, Rancurel C, Bernard T, Lombard V, and Henrissat B. (2009). The Carbohydrate-Active EnZymes database (CAZy): an expert resource for Glycogenomics. Nucleic Acids Res. 2009;37(Database issue):D233-8. DOI:10.1093/nar/gkn663 | PubMed ID:18838391 [Cantarel2009]
  2. Davies, G.J. and Sinnott, M.L. (2008) Sorting the diverse: the sequence-based classifications of carbohydrate-active enzymes. The Biochemist, vol. 30, no. 4., pp. 26-32. Download PDF version.

    [DaviesSinnott2008]