Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
twitter

MetaCyc Enzyme: 3β-hydroxy sterol glucosyltransferase

Gene: UGT80A2 Accession Number: AT3G07020 (MetaCyc)

Synonyms: AT3G07020, UDP-glucose:3β-hydroxy sterol glucosyltransferase

Species: Arabidopsis thaliana col

Summary:
UGT80A2 can be classified as a UDP-glucose:sterol-glucosyltransferase based on direct in vitro assays [Warnecke97, Sharma07a] as well as evidence that ugt80a2 mutant plants have reduced steryl glycoside and acyl steryl glycoside levels. Steryl glycosides are commonly found in plant membranes but their biological functions remain poorly understood [DeBolt09, Patterson93].

UGT80A2 accepts a broad range of sterol substrates and showed the highest activity with transandrosterone. But, it also acts with dehydroepiandrosterone, pregnenolone, sitosterol, stigmasterol, deactyl 16-DPA, , 3-β-16,17-α-epoxypregnenolene, brassicasterol, and ergosterol. Unlike the related SGTL1 from Withania somnifera, UGT80A2 also acts on cholesterol and 5-α-cholestan-3β-ol. In addition, UGT80A2 did not accept any sugar donors other than UDP-α-D-glucose.

ugt80a2 mutants have reduced seed size [DeBolt09] indicating that steryl glucosides are required for optimal growth and development, but their growth is not severely compromised. There is a related 3β-hydroxy sterol glucosyltransferase in Arabidopsis (UGT80B1 (AT1G43620)) that may compensate for the loss of UGT80A2. Experiments show that ugt80a2/b1 double mutants have normal levels of celluose suggesting that steryl glycosides are not required to prime cellulose synthesis. In addition, these double mutants are not more sensitive to cold stress than wild type plants as measured by ion leakage and survival at 4° C. This suggests that reduced steryl glycoside and acyl steryl glycoside levels do not impact Arabidopsis cold acclimation [DeBolt09].

Locations: plasma membrane

Unification Links: ArrayExpress:Q9M8Z7 , PhylomeDB:Q9M8Z7 , PlantCyc:AT3G07020-MONOMER , Pride:Q9M8Z7 , Protein Model Portal:Q9M8Z7 , SMR:Q9M8Z7 , String:3702.AT3G07020.2-P , TAIR:AT3G07020 , UniProt:Q9M8Z7

Relationship Links: CAZy:IN-FAMILY:GT1 , InterPro:IN-FAMILY:IPR002213 , InterPro:IN-FAMILY:IPR004276 , Panther:IN-FAMILY:PTHR11926 , Pfam:IN-FAMILY:PF00201 , Pfam:IN-FAMILY:PF03033

Gene-Reaction Schematic: ?

Instance reaction of [UDP-α-D-glucose + a sterol = UDP + an O-glucosylsterol + H+] (2.4.1.173):
i1: UDP-α-D-glucose + solasodine = UDP + solasodine 3-O-β-D-glucopyranoside + H+ (2.4.1.173)

GO Terms:

Cellular Component: GO:0005886 - plasma membrane [Nuhse03]

Credits:
Created 04-Feb-2011 by Dreher KA , TAIR


Enzymatic reaction of: β-sitosterol glucosyltransferase (3β-hydroxy sterol glucosyltransferase)

Synonyms: UDP-glucose:3β-hydroxy β-sitosterol glucosyltransferase

EC Number: 2.4.1.173

UDP-α-D-glucose + sitosterol <=> UDP + 3-O-β-D-glucosyl-β-sitosterol + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

Reversibility of this reaction is unspecified.

Summary:
The Vmax of the reaction using sitosterol is 0.6 pmol mg-1 min-1 and the Vmax / Km is 0.01 [Sharma07a].

Kinetic Parameters:

Substrate
Km (μM)
Citations
UDP-α-D-glucose
25.0
[Sharma07a]
sitosterol
59.0
[Sharma07a]


Enzymatic reaction of: 3β-hydroxy sterol glucosyltransferase

EC Number: 2.4.1.173

UDP-α-D-glucose + a sterol <=> UDP + an O-glucosylsterol + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

Reversibility of this reaction is unspecified.


Enzymatic reaction of: stigmasterol glucosyltransferase (3β-hydroxy sterol glucosyltransferase)

Synonyms: UDP-glucose:3β-hydroxy stigmasterol glucosyltransferase

EC Number: 2.4.1.173

UDP-α-D-glucose + stigmasterol <=> UDP + stigmasterol 3-O-β-D-glucoside + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

Reversibility of this reaction is unspecified.

Summary:
The Vmax of the reaction using stigmasterol is 0.7 pmol mg-1 min-1 and the Vmax / Km is 0.02 [1].

Kinetic Parameters:

Substrate
Km (μM)
Citations
UDP-α-D-glucose
25.0
[Sharma07a]
stigmasterol
43.0
[Sharma07a]


Enzymatic reaction of: cholesterol glucosyltransferase (3β-hydroxy sterol glucosyltransferase)

Synonyms: UDP-glucose:3β-hydroxy cholesterol glucosyltransferase

EC Number: 2.4.1.173

UDP-α-D-glucose + cholesterol <=> UDP + cholesteryl-β-D-glucoside + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

Reversibility of this reaction is unspecified.

Summary:
The Vmax of the reaction using cholesterol is 0.007 pmol mg-1 min-1 and the Vmax / Km is 0.02 [Sharma07a].

Kinetic Parameters:

Substrate
Km (μM)
Citations
UDP-α-D-glucose
25.0
[Sharma07a]
cholesterol
56.0
[Sharma07a]


Enzymatic reaction of: brassicasterol glucosyltransferase (3β-hydroxy sterol glucosyltransferase)

Synonyms: UDP-glucose:3β-hydroxy brassicasterol glucosyltransferase

EC Number: 2.4.1.173

UDP-α-D-glucose + brassicasterol <=> UDP + 3-O-β-D-glucosyl-brassicasterol + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

Reversibility of this reaction is unspecified.

Summary:
The Vmax of the reaction using brassicasterol is 0.9 pmol mg-1 min-1 and the Vmax / Km is 0.03 [Sharma07a].

Kinetic Parameters:

Substrate
Km (μM)
Citations
UDP-α-D-glucose
25.0
[Sharma07a]
brassicasterol
30.0
[Sharma07a]


References

DeBolt09: DeBolt S, Scheible WR, Schrick K, Auer M, Beisson F, Bischoff V, Bouvier-Nave P, Carroll A, Hematy K, Li Y, Milne J, Nair M, Schaller H, Zemla M, Somerville C (2009). "Mutations in UDP-Glucose:sterol glucosyltransferase in Arabidopsis cause transparent testa phenotype and suberization defect in seeds." Plant Physiol 151(1);78-87. PMID: 19641030

Nuhse03: Nuhse TS, Stensballe A, Jensen ON, Peck SC (2003). "Large-scale analysis of in vivo phosphorylated membrane proteins by immobilized metal ion affinity chromatography and mass spectrometry." Mol Cell Proteomics 2(11);1234-43. PMID: 14506206

Patterson93: Patterson, G.W., Hugly, S., Harrison D. (1993). "Sterols and phytyl esters of Arabidopsis thaliana under normal and chilling temperatures." Phytochemistry, 33:1381-83.

Sharma07a: Sharma LK, Madina BR, Chaturvedi P, Sangwan RS, Tuli R (2007). "Molecular cloning and characterization of one member of 3beta-hydroxy sterol glucosyltransferase gene family in Withania somnifera." Arch Biochem Biophys 460(1);48-55. PMID: 17324374

Warnecke97: Warnecke DC, Baltrusch M, Buck F, Wolter FP, Heinz E (1997). "UDP-glucose:sterol glucosyltransferase: cloning and functional expression in Escherichia coli." Plant Mol Biol 35(5);597-603. PMID: 9349281


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Mon Nov 24, 2014, biocyc14.