Literature summary for 2.4.1.85 extracted from

Blomstedt, C.K.; O'Donnell, N.H.; Bjarnholt, N.; Neale, A.D.; Hamill, J.D.; Moeller, B.L.; Gleadow, R.M.
Metabolic consequences of knocking out UGT85B1, the gene encoding the glucosyltransferase required for synthesis of dhurrin in Sorghum bicolor (L. Moench) (2016), Plant Cell Physiol., 57, 373-386.

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Cloned(Commentary)

Cloned (Comment)	Organism
gene UGT85B1, DNA and amino acid sequence determination and analysis of wild-type and mutant tcd2 genes. The CYP79A1, CYP71E1 and UGT85B1 genes required for dhurrin synthesis are clustered	Sorghum bicolor

Protein Variants

Protein Variants	Comment	Organism
additional information	construction of a knockout mutant by use of targeted induced local lesions in genomes (TILLING) to identify a line with a mutation resulting in a premature stop codon in the N-terminal region of UGT85B1. Plants homozygous for this mutation do not produce dhurrin and are designated tcd2 (totally cyanide deficient 2) mutants. Phenotype, detailed overview	Sorghum bicolor

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
chloroplast	-	Sorghum bicolor	9507	-

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
UDP-D-glucose + (S)-4-hydroxymandelonitrile	Sorghum bicolor	the glucosylation stabilizes the labile cyanohydrin	UDP + (S)-4-hydroxymandelonitrile beta-D-glucoside	i.e. dhurrin	?

Organism

Organism	UniProt	Comment	Textmining
Sorghum bicolor	Q9SBL1	BTx cultivar, gene UGT85B1	-

Source Tissue

Source Tissue	Comment	Organism	Textmining
leaf	-	Sorghum bicolor	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
UDP-D-glucose + (S)-4-hydroxymandelonitrile	-	Sorghum bicolor	UDP + (S)-4-hydroxymandelonitrile beta-D-glucoside	i.e. dhurrin	?
UDP-D-glucose + (S)-4-hydroxymandelonitrile	the glucosylation stabilizes the labile cyanohydrin	Sorghum bicolor	UDP + (S)-4-hydroxymandelonitrile beta-D-glucoside	i.e. dhurrin	?

Synonyms

Synonyms	Comment	Organism
UGT85B1	-	Sorghum bicolor

General Information

General Information	Comment	Organism
malfunction	plant tcd2 mutants deficient in the enzyme have reduced vigor, being dwarfed, with poor root development and low fertility. The mutant plants accumulate numerous dhurrin pathway-derived metabolites, some of which are similar to those observed in transgenic Arabidopsis thaliana expressing the CYP79A1 and CYP71E1 genes. The tcd2 mutant suffers from self-intoxication because Sorghum does not have a feedback mechanism to inhibit the initial steps of dhurrin biosynthesis when the glucosyltransferase activity required to complete the synthesis of dhurrin is lacking. Phenotype, detailed overview	Sorghum bicolor
metabolism	dhurrin is a cyanogenic glucoside and its synthesis from the amino acid tyrosine is catalysed by two membrane-bound cytochrome P450 enzymes (CYP79A1 and CYP71E1) and a soluble glucosyltransferase (UGT85B1), and is dependent on electron transfer from a P450 oxidoreductase. Dhurrin biosynthesis in Sorghum and the formation of products derived from the different intermediates as part of the detoxification processes or as putative turnover products identified in the tcd2 mutant, overview	Sorghum bicolor
physiological function	enzyme UGT85B1 is essential for formation of dhurrin in sorghum with no co-expressed endogenous UDP-glucosyltransferases able to replace it. Presence of metabolites in the tcd2 mutant which are suggested to be derived from dhurrin via endogenous pathways for nitrogen recovery, indicating which enzymes may be involved in such pathways, metabolites identification by LC-MS	Sorghum bicolor

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Release 2023.1 (January 2023)