CelB (Atu3308) is the noncatalytic, membrane-anchored partner of cellulose synthase CelA in Agrobacterium fabrum C58. Its AcsB/BcsB-family carbohydrate-binding and flavodoxin-like domains are predicted to occupy the periplasm, with a C-terminal transmembrane anchor connecting the protein to the inner membrane. It supports cellulose synthesis and handling of the emerging glucan; glycosyl transfer and the established c-di-GMP switch reside in CelA.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005886 plasma membrane | IEA GO_REF:0000120 | ACCEPT | Summary: Retain membrane-anchored cellulose synthase partner localization. Reason: The target has a signal peptide and C-terminal membrane helix, the specific AcsB/BcsB family assignment, and a curated RuleBase inner-membrane location. The homolog structure independently establishes membrane-anchored periplasmic BcsB architecture. Supporting Evidence: file:AGRFC/celB/celB-uniprot.txt Belongs to the AcsB/BcsB family. PMID:23222542 BcsB is a periplasmic protein that is anchored to the inner membrane via a single, C-terminal TM-helix. |
| GO:0006011 UDP-alpha-D-glucose metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: Replace donor-centric metabolism with the cellulose biosynthetic role. Reason: CelB is a structural component of cellulose synthase; CelA performs UDP-glucose glycosyl transfer. BcsB-specific domains and the homolog BcsAB structure support direct participation by organizing the synthesis complex, independently of mutant necessity. GO:0030244 lies under glucan/polysaccharide biosynthesis. It is not a descendant of UDP-glucose metabolism: this is an explicit role correction, not a claimed hierarchical refinement. Same-role QuickGO checks on E. coli P37652 and P. putida Q88JL3 found the same broad donor-metabolism annotation and no cellulose-biosynthesis row. That absence is not evidence of a gap; the replacement rests on structural participation and the conserved family, not on annotation counting. No duplicate NEW process row is added, and no target GO-CAM was present in the index. Use the bacterial-context subtype GO:0090540 of cellulose biosynthesis; the term adds no new native-output or fibril criterion. CelB contributes structural support to a bacterial synthase; this is a role correction from donor metabolism, not assignment of CelA catalysis. Proposed replacements: bacterial cellulose biosynthetic process Supporting Evidence: file:AGRFC/celB/celB-uniprot.txt Belongs to the AcsB/BcsB family. PMID:23222542 BcsB is a periplasmic protein that is anchored to the inner membrane via a single, C-terminal TM-helix. |
| GO:0016020 membrane | IEA GO_REF:0000002 | MODIFY | Summary: Refine membrane to plasma membrane. Reason: The target signal peptide and C-terminal membrane anchor, together with conserved BcsB structure, identify the inner membrane. Plasma membrane is a checked descendant already present in this review. Proposed replacements: plasma membrane Supporting Evidence: file:AGRFC/celB/celB-uniprot.txt Belongs to the AcsB/BcsB family. PMID:23222542 BcsB is a periplasmic protein that is anchored to the inner membrane via a single, C-terminal TM-helix. |
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Download this section (compressed HTML)Q: What contacts and stoichiometry connect CelB to CelA and other C58 type III cellulose components?
Q: Does purified C58 CelB have a demonstrable glucan-binding or other subunit-specific molecular activity?
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