Showing papers on "Chalcone synthase published in 2003"
TL;DR: A major focus of this review is the integration of information from genetic and biochemical studies with the unique insights gained from protein X-ray crystallography and homology modeling, which generated a number of new predictions regarding both the importance and mechanistic role of various amino acid substitutions observed among functionally diverse type III PKS enzymes.
833 citations
TL;DR: This data is the first evidence that ethylene triggers gene expression related to anthocyanin synthesis in grapes, and the results also confirm the existence of other regulatory modes in the anthOCyanin biosynthetic pathway.
Abstract: The treatment of grape berries (Vitis vinifera L. cv. Cabernet Sauvignon) with the ethylene-releasing compound, 2-chloroethylphosphonic acid (2-CEPA), at veraison is a method known to enhance grape skin colour. We observed that it produced a 6-fold increase, up to 30 pmol g1 FW, of the cluster internal ethylene compared to untreated controls within the 24 h following treatment. This ethylene upsurge was associated with increased levels of chalcone synthase (CHS) and flavanone 3-hydroxylase (F3H) transcripts, which persisted over the following 20 days. Transcript levels of leucoanthocyanidin dioxygenase (LDOX) and UDP glucose-flavonoid 3-O-glucosyl transferase (UFGT) were similarly enhanced by 2-CEPA, although to a lesser extent. The effect on UFGT was confirmed at the protein level by an immunoblot analysis. The transcript accumulation of dihydroflavonol 4-reductase (DFR) was unaffected by 2-CEPA treatment. Examination of the levels of CHS, F3H and UFGT mRNAs in berries during bunch exposure to ethylene, revealed elevated levels of each transcript within the first 6 h of treatment when compared to nonethylene-treated controls. HPLC analyses of berry skin extracts showed that levels of each of the anthocyanins analysed (delphinidin, cyanidin, petunidin, peonidin and malvidin) increased over the 10 days following the ethylene burst, and decreased thereafter. However, anthocyanin levels at harvest were still higher in ethylene treated grapes than in controls. This data is the first evidence that ethylene triggers gene expression related to anthocyanin synthesis in grapes, and in addition, our results also confirm the existence of other regulatory modes in the anthocyanin biosynthetic pathway.
247 citations
TL;DR: Of the three sets of an artificial gene cluster, the third gene cluster conferred on the host the highest ability to produce the flavanones, a new metabolic engineering technique for the production in bacteria of a variety of compounds of plant and animal origin.
Abstract: In plants, chalcones are precursors for a large number of flavonoid-derived plant natural products and are converted to flavanones by chalcone isomerase or nonenzymatically. Chalcones are synthesized from tyrosine and phenylalanine via the phenylpropanoid pathway involving phenylalanine ammonia lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate:coenzyme A ligase (4CL), and chalcone synthase (CHS). For the purpose of production of flavanones in Escherichia coli, three sets of an artificial gene cluster which contained three genes of heterologous origins—PAL from the yeast Rhodotorula rubra, 4CL from the actinomycete Streptomyces coelicolor A3(2), and CHS from the licorice plant Glycyrrhiza echinata—were constructed. The constructions of the three sets were done as follows: (i) PAL, 4CL, and CHS were placed in that order under the control of the T7 promoter (PT7) and the ribosome-binding sequence (RBS) in the pET vector, where the initiation codons of 4CL and CHS were overlapped with the termination codons of the preceding genes; (ii) the three genes were transcribed by a single PT7 in front of PAL, and each of the three contained the RBS at appropriate positions; and (iii) all three genes contained both PT7 and the RBS. These pathways bypassed C4H, a cytochrome P-450 hydroxylase, because the bacterial 4CL enzyme ligated coenzyme A to both cinnamic acid and 4-coumaric acid. E. coli cells containing the gene clusters produced two flavanones, pinocembrin from phenylalanine and naringenin from tyrosine, in addition to their precursors, cinnamic acid and 4-coumaric acid. Of the three sets, the third gene cluster conferred on the host the highest ability to produce the flavanones. This is a new metabolic engineering technique for the production in bacteria of a variety of compounds of plant and animal origin.
229 citations
TL;DR: In this paper, a review of the functionally diverse type III polyketide synthase (PKS) superfamily of plant and bacterial biosynthetic enzymes is presented, with a focus on chalcone synthase.
Abstract: This review covers the functionally diverse type III polyketide synthase (PKS) superfamily of plant and bacterial biosynthetic enzymes. from the discovery of chalcone synthase (CHS) in the 1970s through the end of 2001. A broader perspective is achieved by a comparison of these CHS-like enzymes to mechanistically and evolutionarily related families of enzymes, including the type I and type II PKSs, as well as the thiolases and beta-ketoacyl synthases of fatty acid metabolism. As CHS is both the most frequently occurring and best studied type III PKS, this enzyme's structure and mechanism is examined in detail. The in vivo functions and biological activities of several classes of plant natural products derived from chalcones are also discussed. Evolutionary mechanisms of type III PKS divergence are considered, as are the biological functions and activities of each of the known and functionally divergent type III PKS enzymc families (currently twelve in plants and three in bacteria). A major focus of this review is the integration of information from genetic and biochemical studies with the unique insights gained from protein X-ray crystallography and homology modeling. This structural approach has generated a number of new predictions regarding both the importance and mechanistic role of various amino acid substitutions observed among functionally diverse type III PKS enzymes.
159 citations
TL;DR: The results clearly show that the anthocyanin levels resulting from the application of ABA and 2,4-D were correlated with the expression of anthOCyanin biosynthetic pathway genes.
Abstract: SummaryThe effects of abscisic acid (ABA) and 2,4-dichlorophenoxyacetic acid (2,4-D) on the expression of seven anthocyanin biosynthetic pathway genes in ‘Kyoho’ grape berries were investigated. In untreated berries, the expression of the UDP-glucose-flavonoid: 3-O-glucosyltransferase (UFGT) gene was detected only at 42 d after full bloom (DAB), whereas the phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone-3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR) and leucoanthocyanidin dioxygenase (LDOX) genes were expressed throughout the growing period. ABA increased anthocyanin content in the skin and the expression of PAL, CHS, CHI, DFR and UFGT genes at 7 d after treatment. In contrast, 2,4-D inhibited the accumulation of anthocyanin and the expression of all the genes examined. The results clearly show that the anthocyanin levels resulting from the application of ABA and 2,4-D were correlated with the expression of anthocyanin biosynthetic pathway genes.
153 citations
TL;DR: It is suggested that sugars transported into hypocotyls promote anthocyanin biosynthesis by inducing expression of the biosynthetic genes in radish.
152 citations
TL;DR: Results suggest that flavonoids alleviate heat stress on fertilization success and suggest that pleiotropic effects at the A locus may explain the low frequency of the a allele in natural populations.
Abstract: Flavonoids are thought to function in the plant stress response and male fertility in some, but not all, species. We examined the effects of a self-fertile chalcone synthase null allele, a, for the effects of heat and light stress on fertilization success and flower production in Ipomoea purpurea. Pollen recipients and pollen donors of both homozygous genotypes exhibit reduced fertilization success at high temperatures, indicating that high temperature acts as a stress-lowering fertilization success. Homozygous aa individuals exhibit reduced male and female fertilization success, compared to AA individuals, at high temperatures but not at low temperatures. In addition, aa individuals produce fewer flowers than AA individuals at low temperatures, but not at high temperatures. These results suggest that flavonoids alleviate heat stress on fertilization success. They also suggest that pleiotropic effects at the A locus may explain the low frequency of the a allele in natural populations.
134 citations
TL;DR: The evidence suggests that the difference in nonsynonymous substitution rates between upstream and downstream genes is due to relaxed constraint on the downstream genes rather than a greater frequency of positively selected substitutions.
Abstract: Over a broad taxonomic range that spans monocots and dicots, upstream enzymes of the anthocyanin pigment pathway have evolved less rapidly than downstream enzymes. In this article we show that this pattern is also evident within the genus Ipomoea. Specifically, the most upstream enzyme, chalcone synthase (CHS-D), evolves more slowly than the two most downstream enzymes, ancyocyanidin synthase (ANS) and UDP glucose flavonoid 3-oxy-glucosyltransferase (UFGT). This pattern appears not to be due to variation in mutation rates, because the CHS-D gene exhibits higher synonymous substitution rates than the genes for the other two enzymes. Codon-based tests for positive selection suggest that it has been negligible or absent in all three genes. In addition, the mean number of indel-creating events is four times as high in the downstream genes as in CHS-D. Unlike the downstream genes, CHS-D also exhibits evidence of codon bias. Together, the evidence suggests that the difference in nonsynonymous substitution rates between upstream and downstream genes is due to relaxed constraint on the downstream genes rather than a greater frequency of positively selected substitutions.
128 citations
TL;DR: It is demonstrated that proanthocyanidin biosynthesis can be stimulated in alfalfa forage using an myc-like transgene, and they pave the way for the development of high quality, bloat-safe cultivars with ruminal protein bypass.
Abstract: Three anthocyanin regulatory genes of maize (Zea mays; Lc, B-Peru, and C1) were introduced into alfalfa (Medicago sativa) in a strategy designed to stimulate the flavonoid pathway and alter the composition of flavonoids produced in forage. Lc constructs included a full-length gene and a gene with a shortened 5'-untranslated region. Lc RNA was strongly expressed in Lc transgenic alfalfa foliage, but accumulation of red-purple anthocyanin was observed only under conditions of high light intensity or low temperature. These stress conditions induced chalcone synthase and flavanone 3-hydroxylase expression in Lc transgenic alfalfa foliage compared with non-transformed plants. Genotypes containing the Lc transgene construct with a full-length 5'-untranslated region responded more quickly to stress conditions and with a more extreme phenotype. High-performance liquid chromatography analysis of field-grown tissue indicated that flavone content was reduced in forage of the Lc transgenic plants. Leucocyanidin reductase, the enzyme that controls entry of metabolites into the proanthocyanidin pathway, was activated both in foliage and in developing seeds of the Lc transgenic alfalfa genotypes. Proanthocyanidin polymer was accumulated in the forage, but (+)-catechin monomers were not detected. B-Peru transgenic and C1 transgenic populations displayed no visible phenotypic changes, although these transgenes were expressed at detectable levels. These results support the emerging picture of Lc transgene-specific patterns of expression in different recipient species. These results demonstrate that proanthocyanidin biosynthesis can be stimulated in alfalfa forage using an myc-like transgene, and they pave the way for the development of high quality, bloat-safe cultivars with ruminal protein bypass.
118 citations
TL;DR: Benzophenone derivatives, such as polyprenylated benzoylphloroglucinols and xanthones, are biologically active secondary metabolites that are catalyzed by benzophenone synthase that has been cloned from cell cultures of Hypericum androsaemum and is grouped together with the PKSs that functionally differ from CHS.
Abstract: Summary
Benzophenone derivatives, such as polyprenylated benzoylphloroglucinols and xanthones, are biologically active secondary metabolites. The formation of their C13 skeleton is catalyzed by benzophenone synthase (BPS; EC 2.3.1.151) that has been cloned from cell cultures of Hypericum androsaemum. BPS is a novel member of the superfamily of plant polyketide synthases (PKSs), also termed type III PKSs, with 53–63% amino acid sequence identity. Heterologously expressed BPS was a homodimer with a subunit molecular mass of 42.8 kDa. Its preferred starter substrate was benzoyl-CoA that was stepwise condensed with three malonyl-CoAs to give 2,4,6-trihydroxybenzophenone. BPS did not accept activated cinnamic acids as starter molecules. In contrast, recombinant chalcone synthase (CHS; EC 2.3.1.74) from the same cell cultures preferentially used 4-coumaroyl-CoA and also converted CoA esters of benzoic acids. The enzyme shared 60.1% amino acid sequence identity with BPS. In a phylogenetic tree, the two PKSs occurred in different clusters. One cluster was formed by CHSs including the one from H. androsaemum. BPS grouped together with the PKSs that functionally differ from CHS. Site-directed mutagenesis of amino acids shaping the initiation/elongation cavity of CHS yielded a triple mutant (L263M/F265Y/S338G) that preferred benzoyl-CoA over 4-coumaroyl-CoA.
115 citations
TL;DR: It is proposed that these proteins might have evolved by fusing the catalytic machinery of CHS and β-ketoacyl synthases, the two evolutionarily related members with conserved thiolase fold, to provide a fascinating example of metabolite divergence in CHS-like proteins.
TL;DR: The successful production of plant-specific flavanones in bacteria demonstrates the usefulness of combinatorial biosynthesis approaches not only for the production of various compounds of plant and animal origin but also for the construction of libraries of "unnatural" natural compounds.
Abstract: Chalcones, the central precursor of flavonoids, are synthesized exclusively in plants from tyrosine and phenylalanine via the sequential reaction of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate:coenzyme A ligase (4CL) and chalcone synthase (CHS). Chalcones are converted into the corresponding flavanones by the action of chalcone isomerase (CHI), or non-enzymatically under alkaline conditions. PAL from the yeast Rhodotorula rubra, 4CL from an actinomycete Streptomyces coelicolor A3(2), and CHS from a licorice plant Glycyrrhiza echinata, assembled as artificial gene clusters in different organizations, were used for fermentation production of flavanones in Escherichia coli. Because the bacterial 4CL enzyme attaches CoA to both cinnamic acid and 4-coumaric acid, the designed biosynthetic pathway bypassed the C4H step. E. coli carrying one of the designed gene clusters produced about 450 microg naringenin/l from tyrosine and 750 microg pinocembrin/l from phenylalanine. The successful production of plant-specific flavanones in bacteria demonstrates the usefulness of combinatorial biosynthesis approaches not only for the production of various compounds of plant and animal origin but also for the construction of libraries of "unnatural" natural compounds.
TL;DR: It is proposed that the enzyme is involved in the biosynthesis of lunularic acid, the first example of a STS-type reaction that does not lose the terminal carboxyl group during the ring folding to the end product.
TL;DR: Different expression of these genes, especially of the LhDFR gene, controls the distinct pigmentation pattern in flower organs in both cultivars, indicating that the expression of CHS and DFR genes is independently controlled between tepals and tepal spots.
TL;DR: It is concluded that herbicidal phytotoxicity is correlated with a non-balanced VLCFA pattern, and chalcone synthase was assayed catalyzing the key condensing reaction between malonyl- CoA and coumaroyl-CoA.
Abstract: Very-long-chain fatty acids (VLCFAs) having more than 18 C-atoms (like C20, 22, 24) are formed by a microsomal elongase system of the endoplasmic reticulum. This 4-step catalytic system is strongly inhibited by chloroacetamides with I50-values of 10 to 100 nM. Inhibition depends on the amide structure and on stereospecificity (for e.g. metolachlor). Also structures different from chloroacetamides like cafenstrole or fentrazamide (a tetrazolinone) exhibit strong inhibitory activity. A cell-free assay was developed using isolated microsomes from Allium porrum (leek) with labeled malonyl-CoA and C18, C20 or C22 acyl-CoA as primer substrates. All elongation steps were strongly inhibited by those phytotoxic compounds which also have been found active in the intact plant. While the plant contains in total about 1% VLCFAs, the plasma membrane (plasmalemma) is enriched. Isolated plasma membranes (from cucumber) have a small VLCFA content when treating the intact plant with the herbicides. There is evidence that such membrane looses its stability and function, and we conclude that herbicidal phytotoxicity is correlated with a non-balanced VLCFA pattern. Data with transformed yeast demonstrate that the key target for chloroacetamides is exclusively the condensing starter enzyme (=VLCFA synthase) of the elongase system. An irreversible binding complex of synthase and inhibitor is assumed. Reports in literature indicate that flavonoid and anthocyanin biosynthesis is affected by chloroacetamides. Since it was speculated that this inhibition may cause plant death chalcone synthase was assayed catalyzing the key condensing reaction between malonyl-CoA and coumaroyl-CoA. Also this enzyme was inhibited by chloroacetamides or cafenstrole. Our enzymological studies, however, could demonstrate that this inhibition does not cause the herbicidal effect. — Based on our recent findings a reasoning is presented why resistance of weeds against this class of herbicides is a rare event.
TL;DR: The activities of the enzymes chalcone synthase (CHS) and phenylalanine ammonia-lyase (PAL) were measured in leaf extracts obtained from four cultivars of the common bean and there were significant changes in the activities three days after treatment with salicylic acid or inductive fungus when compared to the control.
Abstract: The activities of the enzymes chalcone synthase (CHS) and phenylalanine ammonia-lyase (PAL) were measured in leaf extracts obtained from four cultivars of the common bean (AB 136, Rio Tibagi, Carioca and Macanudo). Two stages of plant development were examined: plantlets (V2) and the onset of blooming (R6). Initially, the plants were either treated with salicylic acid or inoculated with the delta race of Colletotrichum lindemuthianum (inductive fungus) and after three days they were evaluated for enzyme activity. Afterwards, all plants were inoculated (challenged) with the virulent pathotype 33/95 of C. lindemuthianum except for the water control. Five days later, the activities of PAL and CHS were evaluated. There were significant changes in the activities of both enzymes three days after treatment with salicylic acid or inductive fungus when compared to the control. Five days after inoculation with with the virulent pathotype 33/95 of C. lindemuthianum CHS activity in the Macanudo was similar to control plants that were not treated with salicylic acid or the inductive fungus but inoculated with 33/95 C. lindemuthianum. The increase in enzyme activity after challenge with 33/95 C. lindemuthianum was greatest for the salicylic acid treatment in the cultivar AB 136, followed by Rio Tibagi and Carioca.
TL;DR: Two differentially ozone-sensitive cell lines obtained from Vitis vinifera leaf explants, one richer in polyphenols and brown pigmented (Ph+) and the other phenol-poorer and pale (Ph−), were used as experimental tool for analyzing ozone (O 3 ) stress response.
TL;DR: The observation that the BAS I214L/L215F mutant exhibited chalcone-forming activity in a pH-dependent manner supported a hypothesis that the absence of Phe-215 in BAS accounts for the interruption of the polyketide chain elongation at the diketide stage and provided structural basis for understanding the structure-function relationship of the plant type III PKSs.
TL;DR: Incubation of recombinant THNS with malonyl-CoA showed THN production, as demonstrated by UV and HPLC analyses, and the inactivation, expression, and characterization of the type III PKS homologous SCO1206 gene product as 1,3,6,8-tetrahydroxynaphthalene synthase (THNS) was reported.
Abstract: Sequence analysis of the metabolically rich 8.7-Mbp genome of the model actinomycete Streptomyces coelicolor A3(2) revealed three genes encoding predicted type III polyketide synthases (PKSs). We report the inactivation, expression, and characterization of the type III PKS homologous SCO1206 gene product as 1,3,6,8-tetrahydroxynaphthalene synthase (THNS). Incubation of recombinant THNS with malonyl-CoA showed THN production, as demonstrated by UV and HPLC analyses. The K
m value for malonyl-CoA and the k
cat value for THN synthesis were determined spectrophotometrically to be 3.58±0.85 µM and 0.48±0.03 min−1, respectively. The C-terminal region of S. coelicolor THNS, which is longer than most other bacterial and plant type III PKSs, was shortened by 25 amino acid residues and the resulting mutant was shown to be slightly more active (K
m=1.97±0.19 µM, k
cat=0.75±0.04 min−1) than the wild-type enzyme.
TL;DR: ICX1 is a negative regulator of the cryptochrome 1, phytochrome A, ultraviolet (UV)-B, low temperature, sucrose, and cytokinin induction of CHS expression and/or anthocyanin accumulation, demonstrating that these pathways are regulated either directly or indirectly by at least one common component.
Abstract: Flavonoid biosynthesis gene expression is controlled by a range of endogenous and environmental signals. The Arabidopsis icx1 ( increased chalcone synthase expression 1 ) mutant has elevated induction of CHS ( CHALCONE SYNTHASE ) and other flavonoid biosynthesis genes in response to several stimuli. We show that ICX1 is a negative regulator of the cryptochrome 1, phytochrome A, ultraviolet (UV)-B, low temperature, sucrose, and cytokinin induction of CHS expression and/or anthocyanin accumulation, demonstrating that these pathways are regulated either directly or indirectly by at least one common component. Expression analysis of CHS and other genes ( LTP , CAB , and rbcS ) indicates that ICX1 functions in both seedlings and mature leaf tissue and acts principally in the epidermis, consistent with the alterations in epidermal development seen in icx1 . The mutant was unaltered in the synergistic interactions between UV-B, blue, and UV-A light that regulate CHS and we propose a model of action of ICX1 in these responses.
TL;DR: The data indicate that type III polyketide synthases are potential targets of these herbicides, but each combination has to be investigated individually.
TL;DR: A cDNA encoding a stilbene synthase, RtSTS, was isolated from the rhizomes of Tatar rhubarb, Rheum tataricum L. (Polygonaceae), a medicinal plant containing stilbenes and other polyketides as discussed by the authors.
TL;DR: The hypothesis that dimycocerosyl phthiocerol is a virulence factor and thus the many steps involved in its biosynthesis offer potential novel targets for antimycobacterial therapy is supported.
Abstract: Tuberculosis is one of the leading preventable causes of death. Emergence of drug-resistant tuberculosis makes the discovery of new targets for antimycobacterial drugs critical. The unique mycobacterial cell wall lipids are known to play an important role in pathogenesis, and therefore the genes responsible for their biosynthesis offer potential new targets. To assess the possible role of some of the genes potentially involved in cell wall lipid synthesis, we disrupted a mas-like gene, msl7, and a chalcone synthase-like gene, pks10, with phage-mediated delivery of the disruption construct, in which the target gene was disrupted by replacement of an internal segment with the hygromycin resistance gene (hyg). Gene disruption by allelic exchange in the case of each disruptant was confirmed by PCR and Southern blot analyses. Neither msl7 nor pks10 mutants could produce dimycocerosyl phthiocerol, although both could produce mycocerosic acids. Thus, it is concluded that these gene products are involved in the biosynthesis of phthiocerol. Both mutants were found to be attenuated in a murine model, supporting the hypothesis that dimycocerosyl phthiocerol is a virulence factor and thus the many steps involved in its biosynthesis offer potential novel targets for antimycobacterial therapy.
TL;DR: It is concluded that CHS-dependent flavonoid aglycones are possibly endogenous regulators of the basipetal auxin flux, thereby leading to free-auxin accumulation in A. tumefaciens-induced tumors.
Abstract: Agrobacterium tumefaciens-induced plant tumors accumulate considerable concentrations of free auxin. To determine possible mechanisms by which high auxin concentrations are maintained, we examined the pattern of auxin and flavonoid distribution in plant tumors. Tumors were induced in transformants of Trifolium repens (L.), containing the β-glucuronidase (GUS)-fused auxin-responsive promoter (GH3) or chalcone synthase (CHS2) genes, and in transformants of Arabidopsis thaliana (L.) Heynh., containing the GUS-fused synthetic auxin response element DR5. Expression of GH3::GUS and DR5::GUS was strong in proliferating metabolically active tumors, thus suggesting high free-auxin concentrations. Immunolocalization of total auxin with indole-3-acetic acid antibodies was consistent with GH3::GUS expression indicating the highest auxin concentration in the tumor periphery. By in situ staining with diphenylboric acid 2-aminoethyl ester, by thin-layer chromatography, reverse-phase high-performance liquid chromatography, and two-photon laser-scanning microscopy spectrometry, tumor-specific flavones, isoflavones and pterocarpans were detected, namely 7,4′-dihydroxyflavone (DHF), formononetin, and medicarpin. DHF was the dominant flavone in high free-auxin-accumulating stipules of Arabidopsis leaf primordia. Flavonoids were localized at the sites of strongest auxin-inducible CHS2::GUS expression in the tumor that was differentially modulated by auxin in the vascular tissue. CHS mRNA expression changes corresponded to the previously analyzed auxin concentration profile in tumors and roots of tumorized Ricinus plants. Application of DHF to stems, apically pretreated with α-naphthaleneacetic acid, inhibited GH3::GUS expression in a fashion similar to 1-N-naphthyl-phthalamic acid. Tumor, root and shoot growth was poor in inoculated tt4(85) flavonoid-deficient CHS mutants of Arabidopsis. It is concluded that CHS-dependent flavonoid aglycones are possibly endogenous regulators of the basipetal auxin flux, thereby leading to free-auxin accumulation in A. tumefaciens-induced tumors. This, in turn, triggers vigorous proliferation and vascularization of the tumor tissues and suppresses their further differentiation.
TL;DR: Important environmental cues are identified and molecular tools developed that establish V. cornuta as a new model system for the study of the regulation of natural floral color change are developed.
TL;DR: Rec recombinant CHS from Scutellaria baicalensis afforded an unnatural novel triketide, 4-hydroxy-3,5-dimethyl-6-phenyl-pyran-2-one, along with a tetraketide and hexanoyl-CoA and methylmalonyl- coA as substrates.
TL;DR: While phylogenetic analysis placed the three Rubus PKSs in one cluster, suggesting a recent duplication event, their distinct expression patterns suggest that their regulation, and thus function(s), has evolved independently of the structural genes themselves.
TL;DR: Results suggest that in grapevine cell cultures, eutypine strongly affects anthocyanin accumulation by inhibiting UFGT gene expression.
01 Apr 2003
TL;DR: Valerophenone synthase homologue of chalcone synthase (CHS) is the first key enzyme described to be involved in the biosynthesis of bitter acids, the compounds produced in hop lupulin glands valuable for the taste of beer.
Abstract: Valerophenone synthase homologue of chalcone synthase (CHS) is the first key enzyme described to be involved in the biosynthesis of bitter acids, the compounds produced in hop lupulin glands valuable for the taste of beer The complete sequence of a novel homologue of CHS chs 4 was isolated from hop Protein predicted from chs 4 cDNA has 4345 kDa and length 395 amino acids It was found by the analysis of chs 4 flanking sequences that this gene is in the cluster with other CHS homologues — chs 3 and vps The intron identified in chs 4 has been found to be homological to vps and chs 3 introns Expression of chs 4 was partially characterized using reverse transcription polymerase chain reaction and it was found that chs 4 is specifically expressed in the glandular tissue of hop cones likewise vps The predicted protein sequence CHS 4 was compared with other CHS-like proteins