Gene Ontology annotation through association of InterPro records with GO terms
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Combined Automated Annotation using Multiple IEA Methods
Elucidation of the Erwinia uredovora carotenoid biosynthetic pathway by functional analysis of gene products expressed in Escherichia coli.
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Cloned and named the six-gene carotenoid cluster of this organism, establishing crtY as a distinct gene whose product cyclizes lycopene to beta-carotene in the reconstructed pathway.
"Six open reading frames were found and designated the crtE, crtX, crtY, crtI, crtB, and crtZ genes"
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Established, by analysing carotenoids accumulating in E. coli transformants expressing subsets of the cluster, the pathway position of CrtY downstream of lycopene formation.
"The carotenoid biosynthetic pathway in Erwinia uredovora was clarified by analyzing carotenoids accumulated in E. coli transformants in which some of these six genes were expressed"
The carotenoid 7,8-dihydro-psi end group can be cyclized by the lycopene cyclases from the bacterium Erwinia uredovora and the higher plant Capsicum annuum.
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Showed that the Erwinia uredovora (Pantoea ananatis) CrtY cyclase is promiscuous at the ring precursor, converting neurosporene to 7,8-dihydro-beta-carotene via monocyclic beta-zeacarotene and cyclizing zeta-carotene to a bicyclic tetrahydro-beta-carotene.
"Further introduction of the lycopene cyclase gene from E. uredovora (crtY) or the higher plant Capsicum annuum (Icy) resulted in the production of a bicyclic carotenoid, 7,8-dihydro-beta-carotene, via monocyclic beta-zeacarotene."
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Demonstrated that CrtY cyclizes a 7,8-dihydro-psi end group in addition to the usual psi end group, defining its substrate tolerance.
"both lycopene cyclases can cyclize a 7,8-dihydro-psi end group to a 7,8-dihydro-beta end group, in addition to the usual cyclization of the psi end group to the beta end group"
Involvement of NADPH in the cyclization reaction of carotenoid biosynthesis.
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Showed by isotope-labelling that the hydrogen introduced at C-2 during cyclization comes from water, not from NADPH, confirming proton-initiated acid-base catalysis and an indirect (allosteric) role for NAD(P)H.
"the hydrogen atom introduced at C(2) in the cyclization comes from water and not from NADPH"
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Concluded that NADPH is not involved directly in the cyclization and acts indirectly, e.g. as an allosteric activator.
"No hydrogen is transferred from NADPH, which is therefore not involved directly in the cyclization reaction, but must play an indirect role, e.g. as an allosteric activator."
The lycopene cyclase CrtY from Pantoea ananatis (formerly Erwinia uredovora) catalyzes an FADred-dependent non-redox reaction.
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Identified reduced FAD as the essential CrtY cofactor and, using flavin analogues, mass spectrometry and mutagenesis, refuted a mechanism based on cryptic net electron transfer, classifying CrtY as a non-redox flavoprotein.
"We show that reduced FAD is the essential lycopene cyclase (CrtY) cofactor"
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Refuted a redox mechanism for the cyclization, supporting the non-oxidoreductase classification of the enzyme.
"evidence was obtained based on which a catalytic mechanism relying on cryptic (net) electron transfer can be refuted"
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Placed lycopene cyclase among the novel class of non-redox flavoproteins.
"Lycopene cyclase, thus, ranks among the novel class of non-redox flavoproteins"
UniProt entry CRTY_PANAN (P21687)
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Records the double cyclization of lycopene to beta-carotene, the FAD cofactor, the indirect NAD(P)H stimulation, the inner-membrane location and the Glu-199 catalytic mutant, and assigns the beta-carotene biosynthesis pathway.
"Catalyzes the double cyclization reaction which converts"
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Assigns the entry to the lycopene cyclase family and records EC 5.5.1.19, consistent with an isomerase rather than an oxidoreductase.
"Belongs to the lycopene cyclase family."
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Records the E199A mutant as losing activity while still binding FAD, identifying a catalytic residue distinct from the cofactor-binding site.
"E->A: Loss of activity. Still binds FAD."
Deep research report for Pantoea ananatis crtY
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Summarizes the non-redox cycloisomerase chemistry and the membrane-peripheral character of the enzyme, and confirms that no experimental structure of P21687 exists.
"no net oxidation or reduction of the carotenoid occurs"
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Describes CrtY as a membrane-associated peripheral enzyme acting on a membrane-embedded substrate.
"membrane-associated/peripheral enzyme acting on a membrane-embedded substrate"