UreG (Vapar_4248) in Variovorax paradoxus S110 is a 216-amino-acid cytoplasmic SIMIBI-class G3E-family GTPase and nickel metallochaperone (HAMAP rule MF_01389, InterPro IPR004400, PANTHER PTHR31715:SF0, Pfam PF02492) encoded in the chromosome 1 urease gene cluster (Vapar_4240-4249). UreG contains a canonical P-loop GTP-binding motif (residues 24-31, GPVGSGKT) and an invariant Cys-Pro-His (CPH, residues 72-74) metal-binding motif; within the UreD-UreF-UreG activation complex, UreG accepts Ni(2+) from UreE and couples GTP hydrolysis to nickel release into the carbamylated active site of UreC (Vapar_4243).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003924 GTPase activity | IEA GO_REF:0000002 | ACCEPT | Summary: GTPase activity is the defining catalytic function of UreG in urease maturation. Reason: C5CY05 (Vapar_4248) belongs to the SIMIBI G3E GTPase UreG family (HAMAP MF_01389, InterPro IPR004400, PANTHER PTHR31715:SF0) with an intact P-loop GTP-binding site at residues 24-31, and UreG-catalyzed GTP hydrolysis is required for physiological urease activation (PMID:10500143). Supporting Evidence: UniProtKB:C5CY05 CC -!- FUNCTION: Facilitates the functional incorporation of the urease nickel CC metallocenter. This process requires GTP hydrolysis, probably CC effectuated by UreG. {ECO:0000255|HAMAP-Rule:MF_01389}. PMID:10500143 The critical nucleotide-binding site was localized to UreG on the basis of experiments using a variant complex. |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: UreG operates in the bacterial cytoplasm within the UreD-UreF-UreG complex. Reason: C5CY05 is a soluble 216-residue cytoplasmic GTPase (HAMAP rule MF_01389) that activates cytoplasmic apo-urease. Supporting Evidence: UniProtKB:C5CY05 CC -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000255|HAMAP-Rule:MF_01389}. |
| GO:0016151 nickel cation binding | IEA GO_REF:0000120 | ACCEPT | Summary: UreG binds Ni(2+) at its conserved Cys-Pro-His motif during metallocenter delivery. Reason: C5CY05 retains the invariant Cys72-Pro73-His74 (CPH) nickel-binding motif characteristic of bacterial UreG proteins, which bind Ni(2+) with micromolar affinity and release it into the UreC active site upon GTP hydrolysis (PMID:22369361). Supporting Evidence: PMID:22369361 In K. aerogenes this protein is a monomer that binds one Ni or one Zn with Kd values of about 5 ΞΌM |
| GO:0043419 urea catabolic process | IEA GO_REF:0000002 | ACCEPT | Summary: UreG is required to activate the urease complex that catalyzes urea catabolism. Reason: GTP-dependent nickel insertion by UreG is essential to convert inactive apo-UreABC into mature holo-urease for urea catabolism (PMID:10500143). Supporting Evidence: PMID:10500143 The critical nucleotide-binding site was localized to UreG on the basis of experiments using a variant complex. |
| GO:0005525 GTP binding | IC UniProtKB:C5CY05 | NEW | Summary: UreG binds GTP at its conserved P-loop motif (residues 24-31). Reason: Inferred by curator (IC) from GTPase activity (GO:0003924) and the conserved P-loop GTP-binding site at residues 24-31 (GPVGSGKT) annotated by HAMAP rule MF_01389 on UniProtKB:C5CY05. Supporting Evidence: UniProtKB:C5CY05 FT BINDING 24..31 FT /ligand="GTP" FT /ligand_id="ChEBI:CHEBI:37565" FT /evidence="ECO:0000255|HAMAP-Rule:MF_01389" |
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Download this section (compressed HTML)Q: Does Variovorax paradoxus S110 UreG (Vapar_4248) form a nickel-bridged homodimer via its Cys72-Pro73-His74 motif upon receiving Ni(2+) from UreE?
Experiment: Purify wild-type Vapar_4248 and C72A/H74A variants and assay Ni(2+) binding, nucleotide-dependent dimerization by size-exclusion chromatography, and in vitro activation of apo-UreABC.
Hypothesis: Substitution of Cys72 or His74 in the conserved CPH motif of Vapar_4248 abolishes Ni(2+)-dependent dimerization and GTP-dependent activation of V. paradoxus S110 apo-urease.
Type: Site-directed mutagenesis, size-exclusion chromatography, and urease activation assay
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