Difference between revisions of "Carbohydrate Binding Module Family 75"

Latest revision as of 13:20, 18 December 2021

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CAZy DB link
https://www.cazy.org/CBM75.html

Ligand specificities

CBM75 is a small bacterial family containing only 3 members comprising around 290 amino acids and found exclusively in Ruminococci. The only family member characterized is CBM75_RfGH43 from Ruminococcus flavefaciens that specifically binds to xyloglucan [1]. By isothermal titration calorimetry, the affinity to xyloglucan repeating unit XXXG (X comprises glucose decorated at O6 with xylose and G corresponds to undecorated glucose) is similar to the polysaccharide, suggesting that CBM75_RfGH43 has four binding sites that recognize the backbone glucose units. However, the specific binding to xyloglucan and not to other β-glucan polysaccharides indicates that at least some of the xylose side chains also have a major contribution to ligand recognition [1].

Structural Features

No three-dimensional structure has been solved for this CBM family.

Functionalities

Ruminococcus flavefaciens CBM75_RfGH43, is a biding module of a protein containing a glycoside hydrolase family 43 (GH43) and a C-terminal dockerin module [1]. The GH43 catalytic domain, is a member of subfamily 16 (GH43_16) that is populated only with arabinofuranosidases [2]. Indeed, the catalytic module RfGH43 is active against 4-nitrophenyl-α-L-arabinofuranose but does not cleave arabinoxylans and arabinans, suggesting that this enzyme may target arabinofuranose residues that decorate other polysaccharides [1]. The CBMs specificity is consistent with the activity of the appended enzyme. Since CBM75_RfGH43 binds specifically to xyloglucan it was suggested that the enzyme GH43_16 may target arabinofuranose decorations present on xyloglucan from tomato [1].

Family Firsts

First Identified: CBM75_RfGH43 from Ruminococcus flavefaciens [1].
First Structural Characterization: No three-dimensional structure has been solved for this family.

References

All Medline abstracts: PubMed

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 == Ligand specificities ==
-CBM75 is a small bacterial family containing only 3 members comprising around 290 amino acids and found exclusively in ''Ruminococci''. The only family member characterized is CBM75<sub>RfGH43</sub> from ''Ruminococcus flavefaciens'' that specifically binds to xyloglucan <cite>Venditto2016</cite>. By isothermal titration calorimetry, the affinity to xyloglucan repeating unit XXXG (X comprises glucose decorated at O6 with xylose and G corresponds to undecorated glucose) is similar to the polysaccharide, suggesting that CBM75<sub>RfGH43</sub> has four binding sites that recognize the backbone glucose units. However, the specific binding to xyloglucan and not to other β-glucan polysaccharides indicates that at least some of the xylose side chains also have a major contribution to ligand recognition <cite>Venditto2016</cite>.
+CBM75 is a small bacterial family containing only 3 members comprising around 290 amino acids and found exclusively in Ruminococci. The only family member characterized is CBM75<sub>RfGH43</sub> from ''Ruminococcus flavefaciens'' that specifically binds to xyloglucan <cite>Venditto2016</cite>. By isothermal titration calorimetry, the affinity to xyloglucan repeating unit XXXG (X comprises glucose decorated at O6 with xylose and G corresponds to undecorated glucose) is similar to the polysaccharide, suggesting that CBM75<sub>RfGH43</sub> has four binding sites that recognize the backbone glucose units. However, the specific binding to xyloglucan and not to other β-glucan polysaccharides indicates that at least some of the xylose side chains also have a major contribution to ligand recognition <cite>Venditto2016</cite>.
 == Structural Features ==