EC Number   |
General Information |
Reference |
|---|
  1.3.99.31 | evolution |
carotenoid biosynthesis and the evolution of carotenogenesis genes in rust fungi, phylogenetic analysis, detailed overview. A part of the carotenoid biosynthesis pathway in rust fungi is elucidated, with only two genes, CrtYB and CrtI, catalysing the reactions from geranyl-geranyl diphosphate (GGPP) to gamma-carotene. The CrtI gene encodes a phytoene desaturase carries out four successive desaturations of phytoene, through the intermediates phytofluene and neurosporene to lycopene. The CrtYB gene encodes a bifunctional lycopene cyclase/phytoene synthase, which catalyses the condensation of two GGPP into phytoene, as well as the cyclisation of the Psi-end of lycopene to form gamma-carotene |
-, 763110 |
| 1.3.99.31 | evolution |
CRTI-type phytoene desaturases prevailing in bacteria and fungi can form lycopene directly from phytoene while plants employ two distinct desaturases and two cis-tans isomerases for the same purpose |
726300 |
| 1.3.99.31 | evolution |
the enzyme belongs to the CrtI family of enzymes, analysis of the phylogenetic tree of a subset of phytoene desaturases from the CrtI family, overview. Recombinant expression of eight codon optimized CrtI enzymes from different clades in a bacterial system reveals that three CrtI enzymes can catalyse up to six desaturations, forming tetradehydrolycopene. Existence of characteristic patterns of desaturated molecules associated with various CrtI clades. Variations in the reaction rates and binding constants can explain the various carotene patterns observed. Relationship between genetic and functional evolution of certain CrtI enzymes, overview |
-, 759253 |
| 1.3.99.31 | evolution |
the enzyme belongs to the CrtI family of enzymes, analysis of the phylogenetic tree of a subset of phytoene desaturases from the CrtI family, overview. Recombinant expression of eight codon optimized CrtI enzymes from different clades in a bacterial system reveals that three CrtI enzymes can catalyse up to six desaturations, formingtetradehydrolycopene. Existence of characteristic patterns of desaturated molecules associated with various CrtI clades. Variations in the reaction rates and binding constants can explain the various carotene patterns observed. Relationship between genetic and functional evolution of certain CrtI enzymes, overview |
759253 |
| 1.3.99.31 | evolution |
the nucleotide sequence of the crtI gene compared with that of other species, including Kocuria rhizophila and Myxococcus xanthus, proves well conserved during evolution |
763446 |
| 1.3.99.31 | malfunction |
a mutant of Rubrivivax gelatinosus lacking the crtI gene produces only phytoene, indicating that this organism has no other phytoene desaturases. When the crtI deletion mutant is complemented by the three-step phytoene desaturase of Rhodobacter capsulatus, spirilloxanthin and its precursors are not synthesized, although spheroidene and OH-spheroidene are accumulated |
713253 |
| 1.3.99.31 | malfunction |
wild-type Pgt produces reddish-brown urediniospores with yellow cytoplasmic carotenoid pigment and brownish spore wall pigments. Ethyl methanesulfonate (EMS)-induced mutants produce chocolate-coloured and yellow-coloured urediniospores, the mutants lack detectable cytoplasmic carotenoid pigments and sporewall pigments, respectively, viability and infection efficiency of these mutants compared to the corresponding wild-type forms, overview. Reduced fitness is found in the two colour mutants compared to the wild-type isolate, supporting a virulence function for carotenoid pigments in rust fungi, phenotypes, overview |
-, 763110 |
| 1.3.99.31 | metabolism |
carotenoid biosynthesis starts with the symmetrical condensation of two geranylgeranyl diphosphate molecules, forming phytoene. A series of successive desaturation reactions convert phytoene into phytofluene, zeta-carotene, neurosporene, lycopene. These desaturation reactions can be accomplished by a single enzyme (poly-trans pathway) or through a cascade of different enzymes (poly-cis pathway). In algae and plants, four different enzymes are necessary to form the final product (all-trans-lycopene). The phytoene and the zeta-carotene desaturases (PDS and ZDS, respectively) add double bonds in the cis-conformation. ZISO (zeta-carotene isomerase) and CRTISO (prolycopene isomerase) convert the cis-carotenes into di-cis-zeta-carotene and all-trans-lycopene, respectively. By contrast to other phytoene desaturases, CrtI are versatile enzymes classified into four enzymatic subgroups (EC 1.3.99.28, EC 1.3.99.29, EC 1.3.99.30, and EC 1.3.99.31) based on the last product they presumably produce (from zeta-carotene to didehydrolycopene). Carotene diversity can be further expanded in later steps with the addition of one or two rings by lycopene cyclases, thereby producing an extensive variety of symmetrical or asymmetrical cyclised carotenes, such as beta-zeacarotene, dehydro-beta-carotene, gamma-carotene, beta-carotene, and the fungi-specific torulene. When expressed in heterologous hosts, CrtI enzymes exhibit distinct desaturation patterns, CrtI enzyme activities may depend on the experimental conditions and thus be inconsistent with the patterns generated in the natural host. Pantoea ananatis CrtI produces lycopene in vivo, but also tetradehydrolycopene in vitro |
-, 759253 |
| 1.3.99.31 | metabolism |
CrtI produces lycopene exclusively as an end product, not as an intermediate in spirilloxanthin, carotenoid biosynthesis pathway in Rhodospirillum rubrum, overview |
-, 724023 |
| 1.3.99.31 | metabolism |
the carotenoid biosynthesis pathway of Pgt is deduced from the results of the carotenoid pigment analysis and the gene complementation assay: the first C40 carotenoid, phytoene, is synthesised via the condensation of two molecules of GGPP, catalysed by the bifunctional lycopene cyclase/phytoene synthase encoded by the CrtYB gene. Subsequently, phytoene undergoes four steps of desaturation catalysed by the phytoene desaturase encoded by CrtI, through the intermediates phytofluene and neurosporene to lycopene. The CrtYB bifunctional lycopene cyclase/phytoene synthase then catalyses the cyclisation of one Psi-end of lycopene into gamma-carotene. beta-Carotene is not detected in the gene complementation assay |
-, 763110 |
