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
Identification of the carotenoid isomerase provides insight into carotenoid biosynthesis, prolamellar body formation, and photomorphogenesis.
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Arabidopsis CRTISO (ccr2) was identified by positional cloning from mutants with reduced lutein in the light and poly-cis carotene accumulation in the dark.
"The Arabidopsis CRTISO locus was identified by the partial inhibition of lutein synthesis in light-grown tissue and the accumulation of poly-cis-carotene precursors in dark-grown tissue of crtISO mutants"
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Recombinant CRTISO expressed in E. coli isomerises poly-cis carotenoids to all-trans carotenoids, establishing carotenoid isomerase activity.
"enzymatic analysis of CRTISO expressed in Escherichia coli confirmed that the enzyme catalyzes the isomerization of poly-cis-carotenoids to all-trans-carotenoids"
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CRTISO is a third enzyme activity of plant carotene desaturation and, unlike PDS and ZDS, is homologous to the bacterial CRTI-type desaturases.
"carotenoid desaturation in plants requires a third distinct enzyme activity, the carotenoid isomerase (CRTISO), which, unlike phytoene and zeta-carotene desaturases, apparently arose from a progenitor bacterial desaturase"
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Dark-grown crtISO etioplasts accumulate acyclic poly-cis carotenoids instead of xanthophylls and lack prolamellar bodies, showing that carotenoid biosynthesis is required for PLB formation.
"Etioplasts of dark-grown crtISO mutants accumulate acyclic poly-cis-carotenoids in place of cyclic all-trans-xanthophylls and also lack prolamellar bodies (PLBs), the lattice of tubular membranes that defines an etioplast. This demonstrates a requirement for carotenoid biosynthesis to form the PLB."
Cloning of tangerine from tomato reveals a carotenoid isomerase essential for the production of beta-carotene and xanthophylls in plants.
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The tomato tangerine locus encodes CRTISO; tangerine fruit accumulate prolycopene (7Z,9Z,7'Z,9'Z-tetra-cis-lycopene) in place of all-trans-lycopene.
"Fruit of tangerine are orange and accumulate prolycopene (7Z,9Z,7'Z,9'Z-tetra-cis-lycopene) instead of the all-trans-lycopene, which normally is synthesized in the wild type."
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CRTISO is structurally related to the bacterial CRTI phytoene desaturase and its role is proposed to be enabling carotenoid biosynthesis in the dark and in non-photosynthetic tissue.
"CRTISO is a redox-type enzyme structurally related to the bacterial-type phytoene desaturase CRTI ... The function of carotene isomerase in plants presumably is to enable carotenoid biosynthesis to occur in the dark and in nonphotosynthetic tissues."
Analysis in vitro of the enzyme CRTISO establishes a poly-cis-carotenoid biosynthesis pathway in plants.
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Purified tomato CRTISO is an authentic carotene isomerase whose in vitro activity requires redox-active components.
"We show that CRTISO is an authentic carotene isomerase. Its catalytic activity of cis-to-trans isomerization requires redox-active components"
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CRTISO isomerises adjacent 7,9 cis pairs but not single 9-cis bonds, converting 7,9,9'-tri-cis-neurosporene to 9'-cis-neurosporene and di-cis-lycopene to all-trans-lycopene.
"CRTISO isomerizes adjacent cis-double bonds at C7 and C9 pairwise into the trans-configuration, but is incapable of isomerizing single cis-double bonds at C9 and C9′"
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cis-zeta-carotenes are not substrates of CRTISO.
"thus demonstrating that cis- ζ -carotenes are not substrates of CRTISO"
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Purified CRTISO requires a membrane environment; it is inactive on substrate presented in detergent micelles or plain liposomes without bacterial membranes.
"A purified His-tagged form of CRTISO was enzymatically inactive with poly-cis-carotenes when present in Triton X-100 micelles or in liposomes prepared from E. coli lipids or DMPC"
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CRTISO has no desaturase activity despite its homology to CRTI.
"However, CRTISO does not possess any desaturase activity"
Plant carotene cis-trans isomerase CRTISO: a new member of the FAD(RED)-dependent flavoproteins catalyzing non-redox reactions.
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CRTISO binds FAD at its N-terminal dinucleotide-binding site and the reduced flavin drives a reaction with no net redox change.
"The reduced form of this cofactor catalyzes a reaction not involving net redox changes"
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FAD(red) is the required cofactor; FMN(red) is only partially active.
"Based on our data, FAD is the cofactor required by CRTISO ... it is the reduced form of FAD, partially replaceable by FMN red , which drives enzymatic activity of CRTISO"
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CRTISO converts prolycopene formed by PDS and ZDS to all-trans-lycopene, the substrate of the lycopene cyclases.
"CRTISO isomerizes all cis double bonds formed by the action of PDS and ZDS ( 14 ) yielding 7,9,9′,7′-tetra- cis -lycopene 3 (commonly referred to as prolycopene; 15 ) to finally form all- trans -lycopene"
A cis-carotene derived apocarotenoid regulates etioplast and chloroplast development.
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In darkness the conversions catalysed by ZISO and CRTISO are strictly enzyme dependent, whereas light-driven photoisomerisation can substitute in illuminated tissue.
"In the dark, the isomerisation of tri-cis-ζ-carotene to di-cis-ζ-carotene and tetra-cis-lycopene to all-trans-lycopene has a strict requirement for ZISO and CRTISO activity respectively"
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ccr2 etioplasts lack a prolamellar body while retaining normal protochlorophyllide and POR levels; the PLB defect is due to a cis-carotene-derived apocarotenoid signal and is rescued by blocking carotenoid cleavage dioxygenase activity.
"ccr2 is similar to cop1/det1 mutants in that it lacks a PLB in etioplasts, yet it is unique among PLB-deficient mutants in having normal PChlide and POR protein levels ... chemical inhibition of carotenoid cleavage dioxygenase activity restored PLB formation in ccr2 etioplasts during skotomorphogenesis"
Regulation of carotenoid composition and shoot branching in Arabidopsis by a chromatin modifying histone methyltransferase, SDG8.
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The histone methyltransferase SDG8/CCR1 is required for CRTISO transcription; ccr1 leaves retain only about 10% of wild-type CRTISO transcript.
"The level of CRTISO transcripts in ccr1-4 leaf tissue was only 10% that of wild-type leaves"
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A CRTISO genomic fragment complements the lutein deficiency of ccr2, confirming At1g06820 as the ccr2 gene and CRTISO as rate-limiting for lutein.
"ccr2 does not contain any functional CRTISO ... completely restoring lutein levels by 96% in ccr2-1"
Comparative large scale characterization of plant versus mammal proteins reveals similar and idiosyncratic N-α-acetylation features.
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Large-scale N-terminal proteomics that defines transit-peptide cleavage sites and post-translational N-alpha-acetylation of plastid proteins; UniProt derives the CRTISO transit peptide (1-56) and N-acetyl-Val-57 from this dataset.
"post-translational N-α-acetylation of the mature protein after removal of the transit peptide"
Carotenoid biosynthesis in Arabidopsis: a colorful pathway.
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Review of the Arabidopsis carotenoid pathway, its enzymes and regulation; used as background for pathway placement.
"we summarize the current knowledge on the genes and enzymes of the carotenoid biosynthetic pathway"
UniProt record for CRTISO (Q9M9Y8)
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UniProt names Q9M9Y8 prolycopene isomerase, EC 5.2.1.13, with catalytic activity Rhea 30971 (prolycopene = all-trans-lycopene), pathway 'lycopene biosynthesis', FAD/NAD/NADP cofactors by similarity, a 56-residue chloroplast transit peptide and plastid membrane localization by similarity.
"Reaction=7,7',9,9'-tetra-cis-lycopene = all-trans-lycopene;"
Deep research report for CRTISO
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Retrieval support only. The report agrees with the primary literature on identity (At1g06820 = CCR2 = CRTISO, distinct from the paralog At1g57770), on the isomerase reaction and FAD(red) dependence, and on the indirect nature of the etioplast phenotype; identifiers and quotations in this review were verified against the cached publications, UniProt, QuickGO and Rhea, not taken from the report.