GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

UniProtKB keyword KW-0378 (Hydrolase) maps to GO:0016787 (hydrolase activity); KW-0326 (Glycosidase) maps to GO:0016798 (hydrolase activity, acting on glycosyl bonds); KW-0136 (Cellulose degradation) maps to GO:0030245 (cellulose catabolic process), reflecting the GH-family/cellulosomal context of Xgh74A despite its substrate specificity for xyloglucan over cellulose.

GO_REF:0000118

TreeGrafter-generated GO annotations

TreeGrafter places Xgh74A in the GH74 endo-xyloglucanase subfamily (PANTHER:PTN005180743), producing the IEA annotation GO:0010411 (xyloglucan metabolic process). More specific xyloglucan-related terms (GO:0033946, GO:2000899) for this gene come from direct experimental evidence (IDA, PMID:16207921), not from TreeGrafter.

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

Combined evidence sources (InterPro2GO via IPR002105/IPR016134/IPR036439, ARBA, UniRule) produced two IEA annotations: GO:0000272 (polysaccharide catabolic process) and GO:0004553 (hydrolase activity, hydrolyzing O-glycosyl compounds), consistent with the GH74 catalytic activity of Xgh74A on xyloglucan.

PMID:16207921

Two new major subunits in the cellulosome of Clostridium thermocellum: xyloglucanase Xgh74A and endoxylanase Xyn10D.

Xgh74A identified as a major cellulosome component with GH74 catalytic domain and type I dockerin

"Xyloglucanase Xgh74A contains a catalytic module of GHF74 in addition to a C-terminal dockerin module."
Demonstrates endo-xyloglucanase activity, cleaving every fourth beta-1,4-glucan bond in xyloglucan backbone

"It hydrolyses every fourth beta-1,4-glucan bond in the xyloglucan backbone, thus producing decorated cellotetraose units."
High specific activity on tamarind seed xyloglucan (295 U/mg), producing XXXG/XLXG/XXLG/XLLG products

"xyloglucan, which is readily hydrolysed (295 U mg(-1))"
Low activity on CMC, no activity on amorphous cellulose - distinguishing it from cellulases

"Its low activity on CMC and lack of activity on amorphous cellulose indicates recognition of the xylosidic side chains present in xyloglucan"
First xyloglucanase identified in C. thermocellum cellulosome

"Xgh74A is the first xyloglucanase identified in C. thermocellum and the only enzyme in the cellulosome that hydrolyses tamarind xyloglucan."

PMID:16772298

Crystal structures of Clostridium thermocellum xyloglucanase, XGH74A, reveal the structural basis for xyloglucan recognition and degradation.

Crystal structure reveals complex subsite specificity accommodating seventeen monosaccharide moieties

"The structures, in combination with mutagenesis data on the catalytic residues and the kinetics and specificity of xyloglucan hydrolysis reveal a complex subsite specificity accommodating seventeen monosaccharide moieties of the multibranched substrate in an open substrate binding terrain."

file:ACET2/Q70DK5/Q70DK5-deep-research-falcon.md

Deep research summary for xghA/Q70DK5

Xgh74A is extracellular and incorporated into the C. thermocellum cellulosome through its type I dockerin

"Xgh74A is an extracellular, dockerin-bearing cellulosomal enzyme incorporated into CipA scaffoldin complexes"
Functions as endo-xyloglucanase with preference for cleavage at unbranched glucosyl residues

"Functions as an endo-xyloglucanase (cleaves xyloglucan backbone); reported preference to cleave at unbranched glucosyl residues in xyloglucan"