EngO is a non-cellulosomal glycoside hydrolase family 9 (GH9) endoglucanase from Clostridium cellulovorans. Unlike cellulosomal cellulases (EngK, EngL), EngO lacks a dockerin domain and is not incorporated into the cellulosome complex. Instead, it functions as a free secreted enzyme with its own carbohydrate-binding modules (CBMs) for substrate targeting. EngO contains a GH9 catalytic domain, CBM (CenC-type), and Ig-like domains. It hydrolyzes internal β-1,4-glycosidic bonds in cellulose, releasing cello-oligosaccharides that complement the action of cellulosomal enzymes.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000272 polysaccharide catabolic process | IEA GO_REF:0000043 | ACCEPT | Summary: This annotation is correct. EngO is an endoglucanase that directly participates in polysaccharide (cellulose) catabolism by hydrolyzing β-1,4-glycosidic bonds. Reason: As a GH9 endoglucanase, EngO directly catalyzes the breakdown of polysaccharides. This function is well-supported by GH9 family characterization. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md Hydrolyzes cellulose to cello‑oligosaccharides that feed uptake/processing pathways |
| GO:0004553 hydrolase activity, hydrolyzing O-glycosyl compounds | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: This annotation is correct but generic. EngO has hydrolase activity on O-glycosyl bonds. More specific terms like GO:0008810 (cellulase activity) better capture its function. Reason: This is a true parent term of the more specific cellulase activity. It's correct but not the most informative annotation for this enzyme. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md GH9 endo-β-1,4-glucanase that hydrolyzes internal glycosidic bonds in cellulose |
| GO:0005975 carbohydrate metabolic process | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: This annotation is too general. EngO participates in cellulose catabolism specifically, not general carbohydrate metabolism. More specific terms exist. Reason: This parent term is overly broad. GO:0030245 (cellulose catabolic process) is the appropriate specific term for EngO function. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md EngO is a GH9 endoglucanase that cleaves internal β-1,4 linkages of cellulose |
| GO:0008810 cellulase activity | IEA GO_REF:0000002 | ACCEPT | Summary: This annotation is correct and represents a core molecular function of EngO. As a GH9 endoglucanase, EngO has cellulase activity that hydrolyzes cellulose. Reason: EngO is a GH9 family endoglucanase with demonstrated cellulase activity. This is the appropriate molecular function annotation. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md EngO is a GH9 endoglucanase that cleaves internal β-1,4 linkages of cellulose, generating cello-oligosaccharides |
| GO:0016787 hydrolase activity | IEA GO_REF:0000043 | MARK AS OVER ANNOTATED | Summary: This annotation is too general. EngO has hydrolase activity, but more specific terms like cellulase activity better describe its function. Reason: This is a very broad parent term. GO:0008810 (cellulase activity) is the appropriate level of specificity for this GH9 enzyme. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md GH9 enzymes are typically inverting endoglucanases |
| GO:0016798 hydrolase activity, acting on glycosyl bonds | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: This annotation is correct but not as specific as GO:0008810. EngO acts on glycosyl bonds in cellulose. Reason: This is a parent term of cellulase activity. It's correct but less informative than the more specific GO:0008810 annotation. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md GH9 enzymes use an inverting acid–base mechanism to hydrolyze β-1,4-glucans |
| GO:0030245 cellulose catabolic process | IEA GO_REF:0000043 | ACCEPT | Summary: This annotation is correct and represents the core biological process for EngO. As an endoglucanase, EngO directly participates in cellulose degradation. Reason: EngO is a non-cellulosomal endoglucanase that catalyzes cellulose hydrolysis. This is the appropriate biological process annotation. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md EngO participates in the initial hydrolytic depolymerization phase of lignocellulose conversion |
| GO:0005576 extracellular region | TAS file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md | NEW | Summary: EngO is secreted and functions extracellularly as a free (non-cellulosomal) enzyme. Unlike EngK and EngL, it does not assemble into the cellulosome. Reason: EngO contains a signal peptide for secretion and operates extracellularly, complementing the cellulosomal enzymes as a free secreted cellulase. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md Secreted extracellular enzyme functioning outside the cell; designated non‑cellulosomal (soluble) rather than dockerin‑bearing cellulosomal subunit |
| GO:0030248 cellulose binding | TAS file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md | NEW | Summary: EngO contains carbohydrate-binding modules (CBMs) that mediate binding to cellulose. This is essential for its function as a non-cellulosomal enzyme. Reason: Unlike cellulosomal enzymes that rely on the scaffoldin CBM for substrate targeting, EngO has its own CBM domains for direct cellulose binding. Supporting Evidence: file:CLOCL/Q6DTY2/Q6DTY2-deep-research-falcon.md GH9s commonly associate with CBM3c/CBM3b and may include Ig-like/galactose‑binding–like modules influencing substrate binding |
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Download this section (compressed HTML)Q: What is the specific CBM composition of EngO and how does it affect substrate binding?
Q: How do non-cellulosomal and cellulosomal enzymes synergize in C. cellulovorans?
Experiment: Comparative kinetic analysis of EngO with and without CBM domains on crystalline vs amorphous cellulose substrates.
Hypothesis: The CBM domains of EngO may confer different substrate binding properties compared to scaffoldin-mediated targeting of cellulosomal enzymes.
Experiment: Synergy assays combining EngO with cellulosome preparations to assess complementarity in cellulose degradation.
Hypothesis: EngO may provide enhanced access to cellulose regions less accessible to the cellulosome complex, improving overall degradation efficiency.
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