Difference between revisions of "Glycoside Hydrolase Family 147"

Revision as of 16:34, 23 February 2019

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Author: ^^^Jonathon Briggs^^^
Responsible Curator: ^^^Harry Gilbert^^^

Glycoside Hydrolase Family GH147
Clan	GH-A
Mechanism	retaining
Active site residues	known
CAZy DB link
http://www.cazy.org/GH147.html

Substrate specificities

The founding member of glycoside hydrolase family 147, BACOVA_05493 from Bacteroides ovatus is a β1,4-galactosidase. The enzyme demonstrates a preference towards longer oligosaccharides and β1,4-galactan, releasing galactopyranose from the oligosaccharide or polysaccharide chain. BACOVA_05493 is unable to hydrolyse β1,4-galactobiose [1].

Kinetics and Mechanism

¹NMR analysis of the galactose product released from BACOVA_05493 action on galactotriose revealed cleavage with retention of anomeric stereochemistry [1]. The enzyme is believed to operate through a classical Koshland double-displacement mechanism.

Catalytic Residues

Hydrophobic cluster analysis showed that BACOVA_05493 is a member of Clan GH-A. Based on this assumption the catalytic nucleophile and general acid/base residues were proposed as Glu300 and Glu203, respectively. This hypothesis was supported by mutagenesis data showing that the E300A and E203A mutants were catalytically inactive [1].

Three-dimensional structures

Currently there is no crystal structure of any member of GH147, although sequence analysis and hydrophobic cluster analysis predicts a fold of an (α/β)₈ barrel.

Family Firsts

First stereochemistry determination: BACOVA_05493 from B. ovatus was shown to have a retaining mechanism [1].
First catalytic nucleophile identification: BACOVA_05493 from B. ovatus [1].
First general acid/base residue identification: BACOVA_05493 from B. ovatus [1].

First 3-D structure: Currently no experimental structure is available, although BACOVA_05493 is predicted to fold into a (α/β)₈ barrel [1].

References

Luis AS, Briggs J, Zhang X, Farnell B, Ndeh D, Labourel A, Baslé A, Cartmell A, Terrapon N, Stott K, Lowe EC, McLean R, Shearer K, Schückel J, Venditto I, Ralet MC, Henrissat B, Martens EC, Mosimann SC, Abbott DW, and Gilbert HJ. (2018). Dietary pectic glycans are degraded by coordinated enzyme pathways in human colonic Bacteroides. Nat Microbiol. 2018;3(2):210-219. DOI:10.1038/s41564-017-0079-1 | PubMed ID:29255254 [Luis2017]

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 * [[Author]]: ^^^Jonathon Briggs^^^
 * [[Responsible Curator]]:  ^^^Harry Gilbert^^^
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 == Substrate specificities ==
-The founding member of GH147, BACOVA_05493 a β1,4-galactosidase demonstrates a preference towards longer oligosaccharides releasing galacopyranose from the oligosaccharide chain. BACOVA_ is unable to hydrolyse galactobiose <cite>Luis2017</cite>.
+The founding member of [[glycoside hydrolase]] family 147, BACOVA_05493 from ''Bacteroides ovatus'' is a β1,4-galactosidase. The enzyme demonstrates a preference towards longer oligosaccharides and &beta;1,4-galactan, releasing galactopyranose from the oligosaccharide or polysaccharide chain. BACOVA_05493 is unable to hydrolyse β1,4-galactobiose <cite>Luis2017</cite>.
 == Kinetics and Mechanism ==
-NMR analysis of the hydrolysis product revealed a retaining mechanism of action <cite>Luis2017</cite>.
+<sup>1</sup>NMR analysis of the galactose product released from BACOVA_05493 action on galactotriose revealed cleavage with retention of anomeric stereochemistry <cite>Luis2017</cite>. The enzyme is believed to operate through a [[classical Koshland double-displacement mechanism]].
 == Catalytic Residues ==
-The catalytic nucleophile and general acid/base residues of the founding member of GH147, BACOVA_05493, were identified as Glu300 and Glu203, respectively <cite>Luis2017</cite>.
+Hydrophobic cluster analysis showed that BACOVA_05493 is a member of Clan GH-A. Based on this assumption the catalytic nucleophile and general acid/base residues were proposed as Glu300 and Glu203, respectively. This hypothesis was supported by mutagenesis data showing that the E300A and E203A mutants were catalytically inactive <cite>Luis2017</cite>.
 == Three-dimensional structures ==
-Currently there is no crystal structure of any member of GH147.
+Currently there is no crystal structure of any member of GH147, although sequence analysis and hydrophobic cluster analysis predicts a fold of an (&alpha;/&beta;)<sub>8</sub> barrel.
 == Family Firsts ==
-;First stereochemistry determination:     BACOVA_05493 from B. ovatus <cite>Luis2017</cite>.
+;First stereochemistry determination:  BACOVA_05493 from ''B. ovatus'' was shown to have a retaining mechanism <cite>Luis2017</cite>.
-;First catalytic nucleophile identification:     BACOVA_05493 from B. ovatus <cite>Luis2017</cite>.
+;First catalytic nucleophile identification:  BACOVA_05493 from ''B. ovatus'' <cite>Luis2017</cite>.
-;First general acid/base residue identification:     BACOVA_05493 from B. ovatus <cite>Luis2017</cite>.
+;First general acid/base residue identification:   BACOVA_05493 from ''B. ovatus'' <cite>Luis2017</cite>.
-;First 3-D structure: Currently not available.
+;First 3-D structure: Currently no experimental structure is available, although BACOVA_05493 is predicted to fold into a (&alpha;/&beta;)<sub>8</sub> barrel <cite>Luis2017</cite>.
 == References ==