Glycosyltransferase Family 38 - Revision history

Harry Brumer: Text replacement - "\^\^\^(.*)\^\^\^" to "$1"

2021-12-18T21:18:23Z

Text replacement - "\^\^\^(.*)\^\^\^" to "$1"

Warren Wakarchuk at 16:59, 29 May 2020

2020-05-29T16:59:04Z

Warren Wakarchuk at 16:18, 29 May 2020

2020-05-29T16:18:32Z

Harry Brumer: adjusted multiple consecutive citations

2020-05-27T23:21:40Z

adjusted multiple consecutive citations

Warren Wakarchuk at 22:29, 27 May 2020

2020-05-27T22:29:35Z

Warren Wakarchuk at 22:25, 27 May 2020

2020-05-27T22:25:31Z

Warren Wakarchuk at 22:19, 27 May 2020

2020-05-27T22:19:32Z

Warren Wakarchuk at 22:15, 27 May 2020

2020-05-27T22:15:47Z

Warren Wakarchuk at 21:48, 27 May 2020

2020-05-27T21:48:01Z

Warren Wakarchuk at 21:23, 27 May 2020

2020-05-27T21:23:57Z

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 {{UnderConstruction}}
-* [[Author]]: ^^^Warren Wakarchuk^^^
+* [[Author]]: [[User:Warren Wakarchuk|Warren Wakarchuk]]
-* [[Responsible Curator]]: ^^^Warren Wakarchuk^^^
+* [[Responsible Curator]]: [[User:Warren Wakarchuk|Warren Wakarchuk]]
 ----

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 </gallery>
-The structure is a GT-B fold typical of a metal independent glycosyltransferase, it has 2 non-equivalent Rossmann-like folds.  The structure was solved from a truncated version of the enzyme, which lacks 20 amino acids from the N-terminal end.  There are two protomers in the crystal structure, but biochemical evidence suggests the soluble enzyme exists as a monomer.  There is a hinge region between these domains (F227 to N236) which gives some flexibility in the structure. The structure shows an N-terminal tail which is unstructured and is likely to be a linker to the membrane anchor.  The structure has a large electropositive groove which accomodates the polySia chain.  One of the additional structures obtained for this enzyme is a complex with the synthetic heparin fondaparinux which was a surrogate for the polyanionic polySia. The image shown here is the CDP donor analogue complex which sites on one the Rossmann like domains.
+The structure is a GT-B fold typical of a metal independent glycosyltransferase, it has 2 non-equivalent Rossmann-like folds.  The structure was solved from a truncated version of the enzyme, which lacks 20 amino acids from the N-terminal end.  There are two protomers in the crystal structure, but biochemical evidence suggests the soluble enzyme exists as a monomer.  There is a hinge region between these domains (F227 to N236) which gives some flexibility in the structure. The structure shows an N-terminal tail which is unstructured and is likely to be a linker to the membrane anchor.  The structure has a large electropositive groove which accomodates the polySia chain (right hand panel).  One of the additional structures obtained for this enzyme is a complex with the synthetic heparin fondaparinux which was a surrogate for the polyanionic polySia. The image shown here is the CDP donor analogue complex which sites on one the Rossmann like domains.
 == Family Firsts ==
 ; First general acid/base residue identification: E153, H291
 == References ==

@@ Line 45: / Line 45: @@
 <gallery widths=320px heights=240px perrow=2 caption="PDB ID 5WC6 from GT38 (click images for large versions)">
 File:GT38 3.png
-File:GT38 4.png
+File:Surface 2 cropped.png
 </gallery>
 == Family Firsts ==

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 == 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 <cite>          Cho1994</cite>. 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 <cite>Willis2013</cite>. 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 <cite>Jennings1977</cite> <cite>PuentePolledo</cite><cite>Devi1991</cite><cite>Glode1977</cite>.  ''In vitro'' enzyme reactions have shown that the members of GT-38 require two sialic acids for elongation <cite>Willis2008</cite><cite>Peterson2011</cite><cite>Lindhout2013</cite>, presumably as this mimics the ''in vivo'' lipid primer. The enzymes have been used in applications to modify therapeutic proteins and prepare synthetic vaccines <cite>Lindhout2011</cite><cite>McCarthy2013</cite>, where un-natural acceptors like protein N-glycans have been used.
+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 <cite>Cho1994</cite>. 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 <cite>Willis2013</cite>. 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 <cite>Jennings1977 PuentePolledo Devi1991 Glode1977</cite>.  ''In vitro'' enzyme reactions have shown that the members of GT-38 require two sialic acids for elongation <cite>Willis2008 Peterson2011 Lindhout2013</cite>, presumably as this mimics the ''in vivo'' lipid primer. The enzymes have been used in applications to modify therapeutic proteins and prepare synthetic vaccines <cite>Lindhout2011 McCarthy2013</cite>, where un-natural acceptors like protein N-glycans have been used.
 == Kinetics and Mechanism ==
-Sialic acid transfer occurs with inversion of configuration (from the β-linked CMP-Neu5Ac donor to the
+Sialic acid transfer occurs with inversion of configuration (from the β-linked CMP-Neu5Ac donor to the α-2,8-linked polySia), and polyST has been proposed to follow a SN2-like direct displacement mechanism. While H291 could act as a catalytic acid to stabilize the nucleotide phosphate-leaving group.
 == Catalytic Residues ==
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 == Three-dimensional structures ==
-          <gallery widths=320px heights=240px perrow=2 caption="PDB ID 5WC6 from GT38 (click images for large versions)">
+<gallery widths=320px heights=240px perrow=2 caption="PDB ID 5WC6 from GT38 (click images for large versions)">
 File:GT38 3.png
 File:GT38 4.png
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 == References ==
 <biblio>
 # Cho1994 pmid=7972078
 # Willis2013 pmid=23610430
 # Jennings1977 pmid=408435
 # PuentePolledo pmid=10052589
 # Devi1991 pmid=1898915
 # Glode1977 pmid=64575
 # Lindhout2013 pmid=23922842
 # Peterson2011 pmid=21278299
 # Lindhout2011 pmid=21502532
 # McCarthy2013 pmid=23949787
 # Willis2008 pmid=18000029
 # Lizak2017 pmid=28724897
 </biblio>
 [[Category:Glycosyltransferase Families|GT038]]

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            <gallery widths=320px heights=240px perrow=2 caption="PDB ID 5WC6 from GT38 (click images for large versions)">
-File:GT38 3.png|top view
+File:GT38 3.png
-File:GT38 4.png|side view
+File:GT38 4.png
 </gallery>