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UniProt functional annotation for Q6VAB4 | ||
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| UniProt code: Q6VAB4. |
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| Organism: | |
Stevia rebaudiana (Stevia) (Eupatorium rebaudianum). |
| Taxonomy: | |
Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta; Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae; asterids; campanulids; Asterales; Asteraceae; Asteroideae; Heliantheae alliance; Eupatorieae; Stevia. |
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| Function: | |
Involved in the biosynthesis of steviol glycosides in leaves (PubMed:15610349, PubMed:30569490, PubMed:31324778, PubMed:31182573). Converts the di-glycoside steviolbioside to the tri-glycoside rebaudioside B (PubMed:15610349, PubMed:31324778). Converts the tri- glycoside stevioside to the tetra-glycoside rebaudioside A (PubMed:15610349, PubMed:27378621, PubMed:30569490, PubMed:31324778, PubMed:31182573). Converts the tetra-glycoside rebaudioside E to the penta-glycoside rebaudioside D (PubMed:31324778). Converts the penta- glycoside rebaudioside D to the hexa-glycoside rebaudioside M (PubMed:31324778). Can glucosylate rubusoside and rebaudioside A in vitro (PubMed:31324778). {ECO:0000269|PubMed:15610349, ECO:0000269|PubMed:27378621, ECO:0000269|PubMed:30569490, ECO:0000269|PubMed:31182573, ECO:0000269|PubMed:31324778}. |
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| Catalytic activity: | |
Reaction=steviolbioside + UDP-alpha-D-glucose = H(+) + rebaudioside B + UDP; Xref=Rhea:RHEA:61752, ChEBI:CHEBI:15378, ChEBI:CHEBI:58223, ChEBI:CHEBI:58885, ChEBI:CHEBI:145009, ChEBI:CHEBI:145013; Evidence={ECO:0000269|PubMed:15610349, ECO:0000269|PubMed:31324778}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:61753; Evidence={ECO:0000269|PubMed:15610349}; |
| Catalytic activity: | |
Reaction=stevioside + UDP-alpha-D-glucose = H(+) + rebaudioside A + UDP; Xref=Rhea:RHEA:61756, ChEBI:CHEBI:9271, ChEBI:CHEBI:15378, ChEBI:CHEBI:58223, ChEBI:CHEBI:58885, ChEBI:CHEBI:145012; Evidence={ECO:0000269|PubMed:15610349, ECO:0000269|PubMed:27378621, ECO:0000269|PubMed:30569490, ECO:0000269|PubMed:31182573, ECO:0000269|PubMed:31324778}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:61757; Evidence={ECO:0000269|PubMed:15610349}; |
| Catalytic activity: | |
Reaction=rebaudioside E + UDP-alpha-D-glucose = H(+) + rebaudioside D + UDP; Xref=Rhea:RHEA:61772, ChEBI:CHEBI:15378, ChEBI:CHEBI:58223, ChEBI:CHEBI:58885, ChEBI:CHEBI:145018, ChEBI:CHEBI:145022; Evidence={ECO:0000269|PubMed:31324778}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:61773; Evidence={ECO:0000269|PubMed:31324778}; |
| Catalytic activity: | |
Reaction=rebaudioside D + UDP-alpha-D-glucose = H(+) + rebaudioside M + UDP; Xref=Rhea:RHEA:61776, ChEBI:CHEBI:15378, ChEBI:CHEBI:58223, ChEBI:CHEBI:58885, ChEBI:CHEBI:145019, ChEBI:CHEBI:145022; Evidence={ECO:0000269|PubMed:31324778}; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:61777; Evidence={ECO:0000269|PubMed:31324778}; |
| Biophysicochemical properties: | |
Kinetic parameters: KM=5.6 uM for UDP-glucose {ECO:0000269|PubMed:31324778}; KM=440 uM for UDP-glucose {ECO:0000269|PubMed:27378621}; KM=4.5 uM for steviolbioside {ECO:0000269|PubMed:31324778}; KM=103.2 uM for steviolbioside {ECO:0000269|PubMed:15610349}; KM=25.5 uM for stevioside {ECO:0000269|PubMed:31324778}; KM=230 uM for stevioside {ECO:0000269|PubMed:27378621}; KM=291.7 uM for stevioside {ECO:0000269|PubMed:15610349}; KM=360 uM for stevioside {ECO:0000269|PubMed:31182573}; KM=9.2 uM for rebaudioside E {ECO:0000269|PubMed:31324778}; KM=54.4 uM for rubusoside {ECO:0000269|PubMed:31324778}; KM=94.2 uM for rebaudioside D {ECO:0000269|PubMed:31324778}; KM=243.4 uM for rebaudioside A {ECO:0000269|PubMed:31324778}; Vmax=11.1 umol/min/mg enzyme toward UDP-glucose {ECO:0000269|PubMed:27378621}; Vmax=9.3 umol/min/mg enzyme toward stevioside {ECO:0000269|PubMed:27378621}; Note=kcat is 4.1 min(-1) with UDP-glucose as substrate (PubMed:31324778). kcat is 32.5 min(-1) with UDP-glucose as substrate (PubMed:31182573). kcat is 4.8 min(-1) with steviolbioside as substrate (PubMed:31324778). kcat is 21.3 min(-1) with stevioside as substrate (PubMed:31324778). kcat is 33.8 min(-1) with stevioside as substrate (PubMed:31182573). kcat is 41.8 min(-1) with rebaudioside E as substrate (PubMed:31324778). kcat is 5.9 min(-1) with rubusoside as substrate (PubMed:31324778). kcat is 3.3 min(-1) with rebaudioside D as substrate (PubMed:31324778). kcat is 0.12 min(-1) with rebaudioside A as substrate (PubMed:31324778). {ECO:0000269|PubMed:31182573, ECO:0000269|PubMed:31324778}; pH dependence: Optimum pH is 7.0-8.5 with stevioside as substrate (at 40 degrees Celsius). {ECO:0000269|PubMed:27378621}; Temperature dependence: Optimum temperature is 40 degrees Celsius with stevioside as substrate (at pH 7.0). {ECO:0000269|PubMed:27378621}; |
| Subunit: | |
Monomer. {ECO:0000269|PubMed:31182573, ECO:0000269|PubMed:31324778}. |
| Induction: | |
Induced by blue light and red:far-red light in a ratio of 1.22. {ECO:0000269|PubMed:28215607}. |
| Biotechnology: | |
Overexpression of UGT76G1 in Stevia leaves increases the rebaudioside A/stevioside ratio more than 5-fold without compromising plant development or changes in total steviol glycoside content (PubMed:30569490). Rebaudioside A has the advantage to be sweeter and have less bitter aftertaste than stevioside (PubMed:30569490). {ECO:0000269|PubMed:30569490}. |
| Miscellaneous: | |
Leaves of the 'sweet herb' Stevia rebaudiana contain a mix of steviol glycosides, compounds that are unique in the plant world because of their intense sweetness and high concentration in leaf tissue (Probable). Stevia leaves have been used as natural sweeteners in South America for centuries (Probable). {ECO:0000305}. |
| Similarity: | |
Belongs to the UDP-glycosyltransferase family. {ECO:0000305}. |
Annotations taken from UniProtKB at the EBI.