Glycoside Hydrolase Family 164

This page is currently under construction. This means that the Responsible Curator has deemed that the page's content is not quite up to CAZypedia's standards for full public consumption. All information should be considered to be under revision and may be subject to major changes.

• Author: ^^^Zachary Armstrong^^^
• Responsible Curator: ^^^Gideon Davies^^^

---

Glycoside Hydrolase Family GH164
Clan	GH-A
Mechanism	retaining
Active site residues	known
CAZy DB link
https://www.cazy.org/GH164.html

Substrate specificities

The defining member of glycoside hydrolase family 164, a β-mannosidase from Bacteroidetes salyersiae (Bs164, GenbankID: EIY59668.1), was identified initially identified through rational bioinformatic selection of enzyme targets [1]. Although Bs164 was initially reported as an α-mannosidase, subsequent detailed biochemical characterization and structure determination revealed that was instead a β-mannosidase [2]. This enzyme is an exo-acting and is capable of cleaving mannooligos and β-mannosides[2].

Kinetics and Mechanism

Content is to be added here.

Catalytic Residues

Content is to be added here.

Three-dimensional structures

Figure 1. The trimeric structure of Bs164 is shown in panel A. All three protomers are shown with a surface and each chain is displayed as a cartoon diagram coloured by domain. B shows the structure of one protomer. Domain A, which has a (β/α)8 fold, is shown in green with subdomain H is shown in magenta, domain B, containing a mixed β-sheet, is shown in red and the β-sandwich of domain C is shown in blue.

To date only the structure of Bacteroidetes salyersiae β-mannosidase (Bs164) has been solved. Bs164 exists as a donut shaped trimer, see figure 1A. Each trimer-donut has an outer diameter of approximately 100 Å and an internal diameter of between 30 and 35 Å. The individual Bs164 chains contain three clearly defined domains: a modified (β/α)8 barrel, a domain containing a seven membered mixed β-sheet sandwiched between α-helices, and a β-sheet domain (Figure 1B). This domain architecture is quite similar to that seen for family GH42 enzymes [3], but is previously unseen for β-mannosidases.

Family Firsts

First sterochemistry determination

Bacteroides salyersiae β-mannosidase by NMR [2]

First catalytic nucleophile identification

Bacteroides salyersiae β-mannosidase by 2-fluoromannose labeling and kinetic analysis of mutants [2]

First general acid/base residue identification

Bacteroides salyersiae β-mannosidase by kinetic analysis of mutants [2]

First 3-D structure of a GH1 enzyme

Bacteroides salyersiae β-mannosidase [2]

References

1. Helbert W, Poulet L, Drouillard S, Mathieu S, Loiodice M, Couturier M, Lombard V, Terrapon N, Turchetto J, Vincentelli R, and Henrissat B. (2019). Discovery of novel carbohydrate-active enzymes through the rational exploration of the protein sequences space. Proc Natl Acad Sci U S A. 2019;116(13):6063-6068. DOI:10.1073/pnas.1815791116 |
2. Armstrong Z and Davies GJ. (2020). Structure and function of Bs164 β-mannosidase from Bacteroides salyersiae the founding member of glycoside hydrolase family GH164. J Biol Chem. 2020;295(13):4316-4326. DOI:10.1074/jbc.RA119.011591 |
3. Hidaka M, Fushinobu S, Ohtsu N, Motoshima H, Matsuzawa H, Shoun H, and Wakagi T. (2002). Trimeric crystal structure of the glycoside hydrolase family 42 beta-galactosidase from Thermus thermophilus A4 and the structure of its complex with galactose. J Mol Biol. 2002;322(1):79-91. DOI:10.1016/s0022-2836(02)00746-5 |