Carbohydrate Binding Module Family 91

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• Author: Daichi Ito
• Responsible Curator: Elizabeth Ficko-Blean

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CAZy DB link

https://www.cazy.org/CBM91.html

Ligand specificities

CBM91 from Paenibacillus xynaniclasticus bound to oat spelt xylan with K_a value of 2.0×10^-5 M^-1, and bound birchwood xylan. But it did not bind to cellulosic substrates (carboxymethyl-cellulose, ball-milled cellulose and lichnan). Therefore, CBM91 can recognize and bind to insoluble xylan [1].

Structural Features

Figure 1. The structure of PxXyl43A and CBM91. The prediction structure by Alpha Fold 2 of CBM91(red). This CBM91 is appended to the catalytic domain of PxXyl43A(green).

Alpha Fold 2 structure analysis of PxCBM91 exhibited a β-sandwich fold consisted of 12 β-strands and two opposing antiparallel beta sheets. The concave surface and loops around it connecting the β-strands possesse several hydrophobic amino acid residues, the surface is expected to be the binding site.

Functionalities

CBM91 often is connected to the β-xylosidases belonging to glycoside hydrolase family 43 ([GH43]). CBM91 binds to the substrates and would place the catalytic domain in the vicinity of substrates in which substrate concentration is high. These enzymes would utilize CBM91 as a tool for efficient saccharification in combination with other xylanases which release xylobiose and/or xylo-oligosaccharides from insoluble substrates.

Family Firsts

First Identified

PxCBM91 from PxXyl43A of Paenibacillus xynaniclasticus strain TW1 [1].

First Structural Characterization

β-D-xylosidase, a family 43 glycoside hydrolase from Clostridium acetobutylicum ATCC 824 PDB ID 1Y7B.

References

1. Ito D, Nakano E, Karita S, Umekawa M, Ratanakhanokchai K, and Tachaapaikoon C. (2022). Characterization of a GH Family 43 β-Xylosidase Having a Novel Carbohydrate-binding Module from Paenibacillus xylaniclasticus Strain TW1. J Appl Glycosci (1999). 2022;69(3):65-71. DOI:10.5458/jag.jag.JAG-2022_0001 |