Carbohydrate Binding Module Family 55

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• Author: ^^^John Samuelson^^^
• Responsible Curator: ^^^Elizabeth Ficko-Blean^^^

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CAZy DB link

http://www.cazy.org/CBM55.html

Ligand specificities

A CBM55, which is ~60-aa long and contains eight cysteines in conserved positions, was first identified at the N-terminus of the GH18 chitinase of Entamoeba histolytica, the protist that causes dysentery and liver abscess (Fig. 1) [1, 2]. CBM55 members are also present at the N-termini of Jessie 3 lectins, which contain a self-aggregating (daub) domain, while CBM55 is the only domain in Jessie 1 and Jessie 2 lectins [3]. CBM55 members are present in GH18 chitinases and Jessie lectins of all five Entamoeba species that have been sequenced. CBM55 members are absent from other eukaryotes, eubacteria, and archaea, and so the CBM55 motif appears to have been “created from scratch” by the common ancestor to Entamoebae. CBM55s of E. histolytica chitinase, Jessie 1, and Jessie 3 lectins, each expressed under a constitutive actin promoter in transformed trophozoites, demonstrated binding to chitin beads [1].

Structural Features

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

• Fold: Structural fold (beta trefoil, beta sandwich, etc.)
• Type: Include here Type A, B, or C and properties
• Features of ligand binding: Describe CBM binding pocket location (Side or apex) important residues for binding (W, Y, F, subsites), interact with reducing end, non-reducing end, planar surface or within polysaccharide chains. Include examples pdb codes. Metal ion dependent. Etc.

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

1. Van Dellen K, Ghosh SK, Robbins PW, Loftus B, and Samuelson J. (2002). Entamoeba histolytica lectins contain unique 6-Cys or 8-Cys chitin-binding domains. Infect Immun. 2002;70(6):3259-63. DOI:10.1128/IAI.70.6.3259-3263.2002 |
2. de la Vega H, Specht CA, Semino CE, Robbins PW, Eichinger D, Caplivski D, Ghosh S, and Samuelson J. (1997). Cloning and expression of chitinases of Entamoebae. Mol Biochem Parasitol. 1997;85(2):139-47. DOI:10.1016/s0166-6851(96)02817-4 |