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Difference between revisions of "Glycoside Hydrolase Family 98"

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* [[Author]]: [[User:Fathima Shaikh|Fathima Shaikh]]
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{| {{Prettytable}}  
 
{| {{Prettytable}}  
 
|-
 
|-
|{{Hl2}} colspan="2" align="center" |'''Glycoside Hydrolase Family GHnn'''
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|{{Hl2}} colspan="2" align="center" |'''Glycoside Hydrolase Family GH98'''
 
|-
 
|-
 
|'''Clan'''     
 
|'''Clan'''     
|GH-x
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|Not assigned
 
|-
 
|-
 
|'''Mechanism'''
 
|'''Mechanism'''
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|{{Hl2}} colspan="2" align="center" |'''CAZy DB link'''
 
|{{Hl2}} colspan="2" align="center" |'''CAZy DB link'''
 
|-
 
|-
| colspan="2" |http://www.cazy.org/fam/GHnn.html
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| colspan="2" |{{CAZyDBlink}}GH98.html
 
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== Substrate specificities ==
 
== Substrate specificities ==
The glycoside hydrolases of this family are endo-β-galactosidases. No other activities have been reported. Family 98 glycoside hydrolases are unique in their specificity towards cleavage of A and B trisaccharides from glycoconjugates <cite> Ashida2005 Higgins2009 Shaikh2009</cite>. The presence of a L-fucose residue on the substrate is essential for activity of some members of this family (EABase, Sp4GH98) <cite> Ashida2005 Higgins2009 Shaikh2009</cite>. The crystal structure of Sp3GH98 suggests that the fucose residue is not required as a specificity determinant in this enzyme <cite>Higgins2009</cite>.  
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The [[glycoside hydrolase]]s of this family are [[endo]]-β-galactosidases. No other activities have been reported. Family 98 glycoside hydrolases are unique in their specificity towards cleavage of the type II core [gal(β1-4)glcNAc] in the AB blood group antigens (EABase, Sp3GH98) and Lewis<sup>Y</sup> antigens (SpGH98) <cite>Ashida2005 Higgins2009 Shaikh2009</cite>. These enzymes are capable of processing these glycans when presented on cell surfaces thus destroying the antigens <cite>Ashida2005 Higgins2009</cite>.  
  
 
== Kinetics and Mechanism ==
 
== Kinetics and Mechanism ==
 
+
Family GH98 galactosidases are [[inverting]] enzymes, as first shown by NMR monitoring of the Sp4GH98-catalyzed hydrolysis of the Lewis<sup>Y</sup> tetrasaccharide <cite>Higgins2009</cite>. EABase was also shown to act through an inverting enzyme by NMR monitoring of the EABase catalysed hydrolysis of an artificial substrate, DNP-A-trisaccharide <cite>Shaikh2009</cite>. These results are contrary to the initial predictions made by Rigden <cite>Rigden2005</cite>. EABase follows normal Michaelis-Menten kinetics <cite>Shaikh2009</cite>.
Family GH98 galactosidases are inverting enzymes, as first shown by NMR monitoring of the Sp4GH98 catalyzed hydrolysis of the LewisY tetrasaccharide <cite>Higgins2009</cite>. EABase was also shown to act through an inverting enzyme by NMR monitoring of the EABase catalysed hydrolysis of an artificial substrate, DNP-A-trisaccharide <cite>Shaikh2009</cite>. These results are contrary to the initial predictions made by Rigden <cite>Rigden2005</cite>. EABase follows normal Michaelis-Menten kinetics <cite>Shaikh2009</cite>.
 
 
 
  
 
== Catalytic Residues ==
 
== Catalytic Residues ==
 
+
The [[general base]], an aspartate and glutamate diad, and the [[general acid]], glutamate, were identified through the crystal structures of Sp3GH98 and Sp4GH98 in complex with the A trisaccharide and H disaccharide, respectively, and confirmed by site-directed mutagenesis <cite>Higgins2009</cite>. Similar results were obtained through kinetic studies of the corresponding acid and base mutants of EABase with the artificial substrate dinitrophenyl A-trisaccharide.  Further biochemical evidence for the catalytic acid residue was obtained by comparison between the activity of the acid mutant and the p''K''<sub>a</sub> of the leaving group of the substrate <cite>Shaikh2009</cite>.
The catalytic base, an aspartate and glutamate diad, and the catalytic acid, glutamate, were identified through the crystal structures of Sp3GH98 and Sp4GH98 in complex with the A trisaccharide and H disaccharide respectively, and confirmed by site-directed mutagenesis <cite>Higgins2009</cite>. Similar results were obtained through kinetic studies of the corresponding acid and base mutants of EABase with the artificial substrate DNP-A-trisaccharide.  Further biochemical proof for the catalytic acid residue was obtained by comparison between the activity of the acid mutant and the pKa of the leaving group of the substrate <cite>Shaikh2009</cite>.
 
  
 
== Three-dimensional structures ==
 
== Three-dimensional structures ==
 
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The first crystal structures from family 98 were the Sp3GH98 and Sp4GH98 enzymes from ''S. pneumoniae'' in complex with the A trisaccharide and H disaccharide respectively <cite>Higgins2009</cite>. Both structures feature a (α/β)<sub>8</sub> barrel in the catalytic domain with an adjoining β-sandwich domain that contributes to the architecture of the active site and helps define the respective specificities of the enzymes <cite>Higgins2009</cite>
The first crystal structures from family 98 were the Sp3GH98 and Sp4GH98 enzymes from ''S. pneumoniae'' in complex with the A trisaccharide and H disaccharide respectively <cite>Higgins2009</cite>. Both structures feature a (α/β)<sub> 8</sub> barrel in the catalytic domain <cite>Higgins2009</cite>
 
 
 
  
 
== Family Firsts ==
 
== Family Firsts ==
 +
;First sterochemistry determination
 +
:''Streptococcus pneumoniae'' TIGR4 endo-beta-galactosidase Sp4GH98 by NMR <cite>Higgins2009</cite>.
 +
;First [[general base]] identification
 +
:''Streptococcus pneumoniae'' SP3-BS71 endo-beta-galactosidase Sp3GH98 <cite>Higgins2009</cite>.
 +
:''Streptococcus pneumoniae'' TIGR4 endo-beta-galactosidase Sp4GH98 <cite>Higgins2009</cite>.
  
;First sterochemistry determination:  
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;First [[general acid]] identification
 
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:''Streptococcus pneumoniae'' SP3-BS71 endo-beta-galactosidase Sp3GH98 <cite>Higgins2009</cite>.
''Streptococcus pneumoniae'' TIGR4 endo-b-galactosidase Sp4GH98 by NMR <cite>Higgins2009</cite>.
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:''Streptococcus pneumoniae'' TIGR4 endo-beta-galactosidase Sp4GH98 <cite>Higgins2009</cite>.
;First catalytic base identification:
 
 
 
Streptococcus pneumoniae SP3-BS71 endo-b-galactosidase Sp3GH98 <cite>Higgins2009</cite>.
 
 
 
Streptococcus pneumoniae TIGR4 endo-b-galactosidase Sp4GH98 <cite>Higgins2009</cite>.
 
;First catalytic acid identification:  
 
Streptococcus pneumoniae SP3-BS71 endo-b-galactosidase Sp3GH98 <cite>Higgins2009</cite>.
 
 
 
Streptococcus pneumoniae TIGR4 endo-b-galactosidase Sp4GH98 <cite>Higgins2009</cite>.
 
 
 
;First 3-D structure:
 
Streptococcus pneumoniae SP3-BS71 endo-b-galactosidase Sp3GH98 <cite>Higgins2009</cite>.
 
  
Streptococcus pneumoniae TIGR4 endo-b-galactosidase Sp4GH98 <cite>Higgins2009</cite>.
+
;First 3-D structures
 +
:''Streptococcus pneumoniae'' SP3-BS71 endo-beta-galactosidase Sp3GH98 <cite>Higgins2009</cite>.
 +
:''Streptococcus pneumoniae'' TIGR4 endo-beta-galactosidase Sp4GH98 <cite>Higgins2009</cite>.
  
 
== References ==
 
== References ==
 
<biblio>
 
<biblio>
#Ashida2005 pmid=15618227
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# Ashida2005 pmid=15618227
#Higgins2009 pmid=19608744
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# Higgins2009 pmid=19608744
#Shaikh2009 pmid=19630404
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# Shaikh2009 pmid=19630404
#Rigden2005 pmid=16212961
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# Rigden2005 pmid=16212961
  
 
</biblio>
 
</biblio>
  
<!-- ATTN CURATOR: Please delete the "<nowiki>" and "</nowiki>" tags below when you are ready for the page to be included in the "GH Families" category, which is linked on the Main Page; ALSO: REPLACE "nnn" with the family number) -->
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[[Category:Glycoside Hydrolase Families|GH098]]
<nowiki>[[Category:Glycoside Hydrolase Families|GHnnn]]</nowiki>
 

Latest revision as of 13:20, 18 December 2021

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Glycoside Hydrolase Family GH98
Clan Not assigned
Mechanism Inverting
Active site residues Known
CAZy DB link
https://www.cazy.org/GH98.html


Substrate specificities

The glycoside hydrolases of this family are endo-β-galactosidases. No other activities have been reported. Family 98 glycoside hydrolases are unique in their specificity towards cleavage of the type II core [gal(β1-4)glcNAc] in the AB blood group antigens (EABase, Sp3GH98) and LewisY antigens (SpGH98) [1, 2, 3]. These enzymes are capable of processing these glycans when presented on cell surfaces thus destroying the antigens [1, 2].

Kinetics and Mechanism

Family GH98 galactosidases are inverting enzymes, as first shown by NMR monitoring of the Sp4GH98-catalyzed hydrolysis of the LewisY tetrasaccharide [2]. EABase was also shown to act through an inverting enzyme by NMR monitoring of the EABase catalysed hydrolysis of an artificial substrate, DNP-A-trisaccharide [3]. These results are contrary to the initial predictions made by Rigden [4]. EABase follows normal Michaelis-Menten kinetics [3].

Catalytic Residues

The general base, an aspartate and glutamate diad, and the general acid, glutamate, were identified through the crystal structures of Sp3GH98 and Sp4GH98 in complex with the A trisaccharide and H disaccharide, respectively, and confirmed by site-directed mutagenesis [2]. Similar results were obtained through kinetic studies of the corresponding acid and base mutants of EABase with the artificial substrate dinitrophenyl A-trisaccharide. Further biochemical evidence for the catalytic acid residue was obtained by comparison between the activity of the acid mutant and the pKa of the leaving group of the substrate [3].

Three-dimensional structures

The first crystal structures from family 98 were the Sp3GH98 and Sp4GH98 enzymes from S. pneumoniae in complex with the A trisaccharide and H disaccharide respectively [2]. Both structures feature a (α/β)8 barrel in the catalytic domain with an adjoining β-sandwich domain that contributes to the architecture of the active site and helps define the respective specificities of the enzymes [2]

Family Firsts

First sterochemistry determination
Streptococcus pneumoniae TIGR4 endo-beta-galactosidase Sp4GH98 by NMR [2].
First general base identification
Streptococcus pneumoniae SP3-BS71 endo-beta-galactosidase Sp3GH98 [2].
Streptococcus pneumoniae TIGR4 endo-beta-galactosidase Sp4GH98 [2].
First general acid identification
Streptococcus pneumoniae SP3-BS71 endo-beta-galactosidase Sp3GH98 [2].
Streptococcus pneumoniae TIGR4 endo-beta-galactosidase Sp4GH98 [2].
First 3-D structures
Streptococcus pneumoniae SP3-BS71 endo-beta-galactosidase Sp3GH98 [2].
Streptococcus pneumoniae TIGR4 endo-beta-galactosidase Sp4GH98 [2].

References

  1. Anderson KM, Ashida H, Maskos K, Dell A, Li SC, and Li YT. (2005). A clostridial endo-beta-galactosidase that cleaves both blood group A and B glycotopes: the first member of a new glycoside hydrolase family, GH98. J Biol Chem. 2005;280(9):7720-8. DOI:10.1074/jbc.M414099200 | PubMed ID:15618227 [Ashida2005]
  2. Higgins MA, Whitworth GE, El Warry N, Randriantsoa M, Samain E, Burke RD, Vocadlo DJ, and Boraston AB. (2009). Differential recognition and hydrolysis of host carbohydrate antigens by Streptococcus pneumoniae family 98 glycoside hydrolases. J Biol Chem. 2009;284(38):26161-73. DOI:10.1074/jbc.M109.024067 | PubMed ID:19608744 [Higgins2009]
  3. Shaikh FA, Randriantsoa M, and Withers SG. (2009). Mechanistic analysis of the blood group antigen-cleaving endo-beta-galactosidase from Clostridium perfringens. Biochemistry. 2009;48(35):8396-404. DOI:10.1021/bi900991h | PubMed ID:19630404 [Shaikh2009]
  4. Rigden DJ (2005). Analysis of glycoside hydrolase family 98: catalytic machinery, mechanism and a novel putative carbohydrate binding module. FEBS Lett. 2005;579(25):5466-72. DOI:10.1016/j.febslet.2005.09.011 | PubMed ID:16212961 [Rigden2005]

All Medline abstracts: PubMed