PROSITE documentation PDOC00416Clostridium cellulosome enzymes repeated domain signature
Gram-positive, thermophilic anaerobes such as Clostridium thermocellum or Clostridium cellulolyticum secretes a highly active and thermostable cellulase complex (cellulosome) responsible for the degradation of crystalline cellulose [1,2]. The cellulosome contains at least 30 polypeptides, the majority of the enzymes are endoglucanases (EC 3.2.1.4), but there are also some xylanases (EC 3.2.1.8), β-glucosidases (EC 3.2.1.21) and endo-β-1,3-1,4-glucanases (EC 3.2.1.73).
Complete sequence data for many of these enzymes has been obtained. A majority of these proteins contain a highly conserved region of about 65 to 70 residues which is generally (but not always) located in the C-terminus. This region contains a duplicated segment of 24 amino acids. The function of this duplicated segment is not yet known, although it has been suggested that it could be involved in substrate-binding or in calcium-binding [3].
Currently this domain has been found in:
- Endoglucanases A (celA), B (celB), D (celD), E (celE), F (celF), G (celG), H (celH) and X (celX) from Clostridium thermocellum.
- Endoglucanases A (celCCA), C (celCCC), D (celCCD), F (celCCF) and G (celCCG) from Clostridium cellulolyticum.
- Endoglucanase B (engB) from Clostridium cellulovorans.
- Xylanases Y (XynY) and Z (xynZ) from Clostridium thermocellum.
- Endo-β-1,3-1,4 glucanase (licB) from Clostridium thermocellum.
- Cellulose integrating protein (cipA) from Clostridium thermocellum. CipA acts as a scaffolding protein in the cellulosome. It promotes binding of cellulose to the catalytic domains of the cellulolytic enzymes [4].
The pattern we developed spans the first 20 positions of the 24 amino acids segment.
Expert(s) to contact by email: Last update:November 1997 / Text revised.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | Beguin P. |
| Title | Molecular biology of cellulose degradation. | |
| Source | Annu. Rev. Microbiol. 44:219-248(1990). | |
| PubMed ID | 2252383 | |
| DOI | 10.1146/annurev.mi.44.100190.001251 |
| 2 | Authors | Beguin P. Millet J. Aubert J.-P. |
| Title | Cellulose degradation by Clostridium thermocellum: from manure to molecular biology. | |
| Source | FEMS Microbiol. Lett. 79:523-528(1992). | |
| PubMed ID | 1478480 |
| 3 | Authors | Chauvaux S. Beguin P. Aubert J.-P. Bhat K.M. Gow L.A. Wood T.M. Bairoch A. |
| Title | Calcium-binding affinity and calcium-enhanced activity of Clostridium thermocellum endoglucanase D. | |
| Source | Biochem. J. 265:261-265(1990). | |
| PubMed ID | 2302168 |
| 4 | Authors | Gerngross U.T. Romaniec M.P.M. Kobayashi T. Huskisson N.S. Demain A.L. |
| Title | Sequencing of a Clostridium thermocellum gene (cipA) encoding the cellulosomal SL-protein reveals an unusual degree of internal homology. | |
| Source | Mol. Microbiol. 8:325-334(1993). | |
| PubMed ID | 8316083 |
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