Gene Ontology annotation through association of InterPro records with GO terms
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Electronic Gene Ontology annotations created by ARBA machine learning models
Functional analysis of the beta and epsilon lycopene cyclase enzymes of Arabidopsis reveals a mechanism for control of cyclic carotenoid formation.
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The Arabidopsis beta and epsilon lycopene cyclases both use linear, symmetrical lycopene as substrate; the epsilon cyclase adds a single ring to give monocyclic delta-carotene, whereas the beta cyclase adds a ring at both ends to give beta-carotene.
"both enzymes use the linear, symmetrical"
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The epsilon cyclase forms the monocyclic delta-carotene (epsilon,psi-carotene) from lycopene, defining the epsilon-cyclization branch.
"forming the monocyclic delta-carotene (epsilon, psi-carotene)"
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Lycopene cyclization is a key branch point in the carotenoid biosynthetic pathway.
"The cyclization of lycopene (psi, psi-carotene) is a key branch point"
Arabidopsis carotenoid mutants demonstrate that lutein is not essential for photosynthesis in higher plants.
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The lut2 mutation blocks epsilon-ring cyclization and cosegregates with the epsilon cyclase gene, establishing lut2 as a mutation in lycopene epsilon-cyclase.
"phenotype is consistent with a disruption of epsilon ring cyclization."
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lut1 and lut2 are required for lutein biosynthesis but not for beta,beta-carotenoid biosynthesis, placing the epsilon cyclase specifically in the beta,epsilon branch.
"lutein biosynthesis but not for the biosynthesis of beta, beta-carotenoids."
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The epsilon cyclase is a key regulatory step controlling lutein levels and the ratio of lutein to beta,beta-carotenoids.
"regulating lutein levels and the ratio of lutein to beta,beta-carotenoids."
Altered xanthophyll compositions adversely affect chlorophyll accumulation and nonphotochemical quenching in Arabidopsis mutants.
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In lut2, lutein is eliminated and replaced mainly by a stoichiometric increase in violaxanthin and antheraxanthin, showing rerouting from the beta,epsilon to the beta,beta branch when the epsilon cyclase is lost.
"lutein is replaced mainly by a stoichiometric increase in violaxanthin"
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The lut2 mutation eliminates lutein production and is a disruption of the gene encoding lycopene epsilon-cyclase.
"The lut2 mutation eliminates lutein production and is"
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Both zeaxanthin and lutein contribute to nonphotochemical quenching; loss of lutein in lut2 delays and reduces the rapid rise of NPQ.
"both zeaxanthin and lutein contribute to nonphotochemical quenching"
One ring or two? Determination of ring number in carotenoids by lycopene epsilon-cyclases.
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The Arabidopsis lycopene epsilon-cyclase adds one epsilon-ring to the symmetrical linear substrate lycopene (giving monocyclic delta-carotene).
"adds one epsilon-ring to the symmetrical linear substrate lycopene"
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A single amino acid residue acts as a molecular switch for ring number in lycopene epsilon-cyclases.
"A single amino acid was found to act as a molecular switch: lettuce"
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The Arabidopsis LCYe L448H mutant gains bi-epsilon-cyclase activity (adds two epsilon-rings), defining Leu-448 as the residue controlling mono- vs bi-cyclization.
"complementary Arabidopsis LCYe mutant, L448H, added two epsilon-rings."
Elucidation of the beta-carotene hydroxylation pathway in Arabidopsis thaliana.
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Double and triple mutant combinations of the carotenoid ring hydroxylases (CHY1, CHY2, LUT1, LUT5) with LUT2 (lycopene epsilon-cyclase) were constructed to dissect the xanthophyll hydroxylation pathway; chy1chy2lut2 leaves are ~80% beta-carotene.
"constructed double and triple mutant combinations in CHY1, CHY2, LUT1, LUT5 and"
UniProt entry Q38932 (LCYE_ARATH)
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LCYE catalyses the single epsilon-cyclization converting lycopene to delta-carotene (and neurosporene to alpha-zeacarotene) and is required for lutein biosynthesis (EC 5.5.1.18, Rhea:RHEA:55616).
"epsilon-cyclization reaction which converts lycopene to delta-carotene"
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LCYE is required for lutein biosynthesis.
"Required for lutein biosynthesis (PubMed:9789087)."
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LCYE is a multi-pass membrane protein of the plastid (chloroplast) membrane.
"Plastid, chloroplast membrane"
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The lut2 disruption phenotype is delayed greening and virescent seedlings.
"Delayed greening and virescent seedlings."