Carbohydrate Binding Module Family 80

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• Author: ^^^Immacolata Venditto^^^
• Responsible Curator: ^^^Harry Gilbert^^^

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CAZy DB link

http://www.cazy.org/CBM80.html

Ligand specificities

CBM80 is a small bacterial family comprising around 96 amino acids and identified in the Ruminococcus flavefaciens cellulosome [1]. CBM80 displays specificity for β-1,4- and mixed linked β-1,3-1,4-glucans, with some members also binding to β-1,4-mannans. CBM80 is a component of an enzyme that contains catalytic module derived from GH5_4 (CBM80_RfGH5-1/2, and CBM80_RfGH5) with endo-β1,4-glucanases activity. CBM80 is also component of an enzyme that contains GH5_7 catalytic module with β1,4-mannanase activity. The only family member characterized is CBM80_RfGH5-1/2 and the dual specificity of this CBM is consistent with the catalytic modules of the enzymes that hydrolyze β-glucans (GH5_4) or β-mannans (GH5_7) [2]. CBM80_RfGH5-1/2 binds galactomannan in addition to the β-glucans with affinities in the range of 10⁴ to 10⁵ M^-1. Additionally, this CBM binds mannotetraose and not cellotetraose.

Structural Features

The three-dimensional structure of CBM80_RfGH51/2 (5fu3) was solved using single-wavelength anomalous diffraction (SAD) methods and selenomethionyl protein. The apo structure of CBM80_RfGH51/2 (Figure 1) and in complex with mannohexaose and cellohexaose was solved to a resolution of 1.0 Å, 1.4 Å and 1.5 Å respectively [2]. CBM80_RfGH51/2 has a β-sandwich fold and contains two β-sheets, 1 and 2, respectively (Figure 1) [2]. The β-sheet 2 of CBM80_RfGH51/2 presents a planar hydrophobic surface with a parallel orientation of Trp453 and Trp489 and a perpendicular orientation of a third aromatic residue, Trp490. The mannohexaose-CBM80_RfGH51/2 complex revealed electron density for mannohexaose along the hydrophobic surface of β-sheet 2 [2]. The structure of CBM80_RfGH51/2 in complex with cellohexaose revealed electron density for only three glucose units [2].

Functionalities

Content in this section should include, in paragraph form, a description of:

• Functional role of CBM: Describe common functional roles such as targeting, disruptive, anchoring, proximity/position on substrate.
• Most Common Associated Modules: 1. Glycoside Hydrolase Activity; 2. Additional Associated Modules (other CBM, FNIII, cohesin, dockerins, expansins, etc.)
• Novel Applications: Include here if CBM has been used to modify another enzyme, or if a CBM was used to label plant/mammalian tissues? Etc.

Family Firsts

First Identified

Insert archetype here, possibly including very brief synopsis.

First Structural Characterization

Insert archetype here, possibly including very brief synopsis.

References

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. Davies, G.J. and Sinnott, M.L. (2008) Sorting the diverse: the sequence-based classifications of carbohydrate-active enzymes. The Biochemist, vol. 30, no. 4., pp. 26-32. Download PDF version.

5. Boraston AB, Bolam DN, Gilbert HJ, and Davies GJ. (2004). Carbohydrate-binding modules: fine-tuning polysaccharide recognition. Biochem J. 2004;382(Pt 3):769-81. DOI:10.1042/BJ20040892 |
6. Hashimoto H (2006). Recent structural studies of carbohydrate-binding modules. Cell Mol Life Sci. 2006;63(24):2954-67. DOI:10.1007/s00018-006-6195-3 |
7. Shoseyov O, Shani Z, and Levy I. (2006). Carbohydrate binding modules: biochemical properties and novel applications. Microbiol Mol Biol Rev. 2006;70(2):283-95. DOI:10.1128/MMBR.00028-05 |
8. Guillén D, Sánchez S, and Rodríguez-Sanoja R. (2010). Carbohydrate-binding domains: multiplicity of biological roles. Appl Microbiol Biotechnol. 2010;85(5):1241-9. DOI:10.1007/s00253-009-2331-y |
9. Armenta S, Moreno-Mendieta S, Sánchez-Cuapio Z, Sánchez S, and Rodríguez-Sanoja R. (2017). Advances in molecular engineering of carbohydrate-binding modules. Proteins. 2017;85(9):1602-1617. DOI:10.1002/prot.25327 |