Glycoside Hydrolase Family 138

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• Author: ^^^Didier Ndeh^^^
• Responsible Curator: ^^^Harry Gilbert^^^

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Glycoside Hydrolase Family GH138
Clan	none
Mechanism	unknown
Active site residues	unknown
CAZy DB link
http://www.cazy.org/GH138.html

Substrate specificities

Members of GH138 exhibit α-D-galacturonidase activity. This is based on data from the characterisation of the founding member of the family BT0997 encoded by the prominent human gut bacterium B. thetaiotaomicron [1]. BT0997 hydrolyses a fragment (GalA-α1,2(GalA-β1,3)(2MeXyl-α1,3-Fuc-α1,4)Rha-α1,3-Api) of Chain A from the pectic polysaccharide Rhamnogalacturonan II, producing D-galacturonic acid and the resulting oligosaccharide GalA-β1,3(2MeXyl-α1,3Fuc-α1,4)Rha-α1,3Api [1], demonstrating that BT0997 cleaved the D-Gal-α1,2-Rhap linkage. Several members of this family have been identified in gut and environmental bacteria with a majority of the encoding microbes belonging to the Bacteroidetes phylum [2, 3]. This phylum is highly represented in human gut microbial populations [4].

Kinetics and Mechanism

The kinetic mechanism for this family has not been reported.

Catalytic Residues

The catalytic residues for this family have not yet been identified.

Three-dimensional structures

No 3D structure for a member of this family has been currently reported.

Family Firsts

First stereochemistry determination

Currently unknown.

First catalytic nucleophile identification

Currently unknown.

First general acid/base residue identification

Currently unknown.

First 3-D structure

Currently unknown.

References

1. Ndeh D, Rogowski A, Cartmell A, Luis AS, Baslé A, Gray J, Venditto I, Briggs J, Zhang X, Labourel A, Terrapon N, Buffetto F, Nepogodiev S, Xiao Y, Field RA, Zhu Y, O'Neil MA, Urbanowicz BR, York WS, Davies GJ, Abbott DW, Ralet MC, Martens EC, Henrissat B, and Gilbert HJ. (2017). Complex pectin metabolism by gut bacteria reveals novel catalytic functions. Nature. 2017;544(7648):65-70. DOI:10.1038/nature21725 |
2. Lombard V, Golaconda Ramulu H, Drula E, Coutinho PM, and Henrissat B. (2014). The carbohydrate-active enzymes database (CAZy) in 2013. Nucleic Acids Res. 2014;42(Database issue):D490-5. DOI:10.1093/nar/gkt1178 |
3. 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 |
4. Qin J, Li R, Raes J, Arumugam M, Burgdorf KS, Manichanh C, Nielsen T, Pons N, Levenez F, Yamada T, Mende DR, Li J, Xu J, Li S, Li D, Cao J, Wang B, Liang H, Zheng H, Xie Y, Tap J, Lepage P, Bertalan M, Batto JM, Hansen T, Le Paslier D, Linneberg A, Nielsen HB, Pelletier E, Renault P, Sicheritz-Ponten T, Turner K, Zhu H, Yu C, Li S, Jian M, Zhou Y, Li Y, Zhang X, Li S, Qin N, Yang H, Wang J, Brunak S, Doré J, Guarner F, Kristiansen K, Pedersen O, Parkhill J, Weissenbach J, MetaHIT Consortium, Bork P, Ehrlich SD, and Wang J. (2010). A human gut microbial gene catalogue established by metagenomic sequencing. Nature. 2010;464(7285):59-65. DOI:10.1038/nature08821 |