8POF

The crystal structure of RsSymEG1 reveals a unique form of smaller GH7 endoglucanases alongside GH7 cellobiohydrolases in protist symbionts of termites

Summary for 8POF

• Entry DOI: 10.2210/pdb8pof/pdb
• Descriptor: Putative glycosyl hydrolase family7, 2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL, SODIUM ION, ... (4 entities in total)
• Functional Keywords: gh7, endoglucanase, cellulase, hydrolase
• Biological source: Reticulitermes speratus gut symbiotic protist
• Total number of polymer chains: 1
• Total formula weight: 34099.57

Authors

Haataja, T.,Sandgren, M.,Hansson, H.,Stahlberg, J. (deposition date: 2023-07-04, release date: 2023-12-27, Last modification date: 2024-03-27)

Primary citation

Haataja, T.,Hansson, H.,Moriya, S.,Sandgren, M.,Stahlberg, J.
The crystal structure of RsSymEG1 reveals a unique form of smaller GH7 endoglucanases alongside GH7 cellobiohydrolases in protist symbionts of termites.
Febs J., 291:1168-1185, 2024

PubMed Abstract: Glycoside hydrolase family 7 (GH7) cellulases are key enzymes responsible for carbon cycling on earth through their role in cellulose degradation and constitute highly important industrial enzymes as well. Although these enzymes are found in a wide variety of evolutionarily distant organisms across eukaryotes, they exhibit remarkably conserved features within two groups: exo-acting cellobiohydrolases and endoglucanases. However, recently reports have emerged of a separate clade of GH7 endoglucanases from protist symbionts of termites that are 60-80 amino acids shorter. In this work, we describe the first crystal structure of a short GH7 endoglucanase, RsSymEG1, from a symbiont of the lower termite Reticulitermes speratus. A more open flat surface and shorter loops around the non-reducing end of the cellulose-binding cleft indicate enhanced access to cellulose chains on the surface of cellulose microfibrils. Additionally, when comparing activities on polysaccharides to a typical fungal GH7 endoglucanase (Trichoderma longibrachiatum Cel7B), RsSymEG1 showed significantly faster initial hydrolytic activity. We also examine the prevalence and diversity of GH7 enzymes that the symbionts provide to the termite host, compare overall structures and substrate binding between cellobiohydrolase and long and short endoglucanase, and highlight the presence of similar short GH7s in other organisms.

PubMed: 38073120
DOI: 10.1111/febs.17029

Experimental method

X-RAY DIFFRACTION (1.85 Å)