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Background Withania somnifera (Solanaceae), generally known as Indian ginseng, is a medicinal plant that is used in Ayurvedic practice for promoting health and longevity. This study aims to identify the bioactive metabolites from Indian ginseng and elucidate their structures. Methods Withanolides were purified by chromatographic techniques, including HPLC coupled with LC/MS. Chemical structures of isolated withanolides were clarified by analyzing the spectroscopic data from 1D and 2D NMR, and HR-ESIMS experiment. Absolute configurations of the withanolides were established by the application of NMR chemical shifts and ECD calculations. Anti-adipogenic activities of isolates were evaluated using 3T3-L1 preadipocytes with Oil Red O staining and quantitative real-time PCR (qPCR). Results Phytochemical examination of the roots of Indian ginseng afforded to the isolation of six withanolides (1–6), including three novel withanolides, withasilolides G–I (1–3). All the six compounds inhibited adipogenesis and suppressed the enlargement of lipid droplets, compared to those of the control. Additionally, the mRNA expression levels of Fabp4 and Adipsin, the adipocyte markers decreased noticeably following treatment with 25 μM of 1–6. The active compounds (1–6) also promoted lipid metabolism by upregulating the expression of the lipolytic genes HSL and ATGL and downregulating the expression of the lipogenic gene SREBP1. Conclusion The results of our experimental studies suggest that the withasilolides identified herein have anti-adipogenic potential and can be considered for the development of therapeutic strategies against adipogenesis in obesity. Our study also provides a mechanistic rationale for using Indian ginseng as a potential therapeutic agent against obesity and related metabolic diseases.

Various factors related to growing conditions can influence the nutritional quality of plants, including vegetable crops, especially the contents of health-promoting phytochemicals. In this study, the phytochemical contents of spinach (Spinacia oleracea) cultivated under greenhouse and open field conditions were comparatively analyzed using a metabolomic approach with Mass Profiler Professional (MPP) software. S. oleracea, which is one of the well-known leafy vegetables belonging to the family Chenopodiaceae, is cultivated worldwide. Although the nutritional value of spinach is high, the phytochemical contents of spinach cultivated under greenhouse and open field conditions have not been comparatively analyzed. Metabolomic analysis of the methanol (MeOH) extracts of greenhouse-cultivated spinach (GS) and open field-cultivated spinach (OFS) using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS), followed by principal component analysis (PCA) with MPP demonstrated the differential metabolite profiles of GS and OFS. The active compounds 1-3 were isolated and identified using LC-Q-TOF-MS-guided fractionation. Among these, 5,3',4'-trihydroxy-3-methoxy-6,7-methylenedioxyflavone 4'-glucuronide (2) exhibited growth-inhibitory activities against Helicobacter pylori 51. Distribution analysis of compound 2 revealed that the anti-H. pylori compound 2 is an OFS-specific bioactive phytochemical. This indicates that the phytochemical quality of OFS is better than that of GS. These findings will aid in providing vital data for vegetable processors, dieticians, nutritionists, and consumers to select optimal green leafy vegetables.

Calvatia nipponica, a puffball mushroom (Agaricaceae), is thought to be an aphrodisiac, as this mushroom is traditionally known to improve sexual function in males. As part of the systematic study to determine the bioactive secondary metabolites from C. nipponica responsible for aphrodisiac effects, chemical analysis of methanol (MeOH) extracts of the fruiting bodies of C. nipponica resulted in the isolation of two major compounds: N,N-dimethyl-anthranilic acid (1) and (7Z,10Z)-7,10-octadecadienoic acid methyl ester (2). Compounds 1 and 2 were evaluated for cumulative dose-dependent relaxation responses to precontracted penile corpus smooth muscle (PCCSM). Results show that compounds 1 and 2 exhibited a maximum relaxation effect of 20.33 ± 2.18% and 24.63 ± 3.60%, respectively. These findings indicate that compounds 1 and 2, major components of C. nipponica, could potentially be used to treat erectile dysfunction, functioning as natural aphrodisiacs.

Withanolides were purified by chromatographic techniques, including HPLC coupled with LC/MS. Chemical structures of isolated withanolides were clarified by analyzing the spectroscopic data from 1D and 2D NMR, and HR-ESIMS experiment. Absolute configurations of the withanolides were established by the application of NMR chemical shifts and ECD calculations. Anti-adipogenic activities of isolates were evaluated using 3T3-L1 preadipocytes with Oil Red O staining and quantitative real-time PCR (qPCR).Phytochemical examination of the roots of Indian ginseng afforded to the isolation of six withanolides (The results of our experimental studies suggest that the withasilolides identified herein have anti-adipogenic potential and can be considered for the development of therapeutic strategies against adipogenesis in obesity. Our study also provides a mechanistic rationale for using Indian ginseng as a potential therapeutic agent against obesity and related metabolic diseases.

Safflower (Carthamus tinctorius) is an annual herb belonging to the Compositae family, it has a history of use as a food colorant, dye, and medicine in oriental countries. LC-MS-UV-based chemical analysis of extract of the florets of C. tinctorius led to the isolation of two new C10-polyacetylene glycosides, (8Z)-decaene-4,6-diyne-1,10-diol-1-O-&beta, d-glucopyranoside (1) and (8S)-deca-4,6-diyne-1,8-diol-1-O-&beta, d-glucopyranoside (2), together with five known analogs (3&ndash, 7). The structures of the new compounds were determined by using 1D and 2D NMR spectroscopic data and HR-MS data, as well as chemical transformations. Of compounds 1&ndash, 7, compounds 2, 3, and 4 inhibited the adipogenesis of 3T3-L1 preadipocytes, whereas compounds 1 and 6 promoted adipogenesis. Compounds 2, 3, and 4 also prevented lipid accumulation through the suppression of the expression of lipogenic genes and the increase of the expression of lipolytic genes. Moreover, compounds 3 and 4 activated AMPK, which is known to facilitate lipid metabolism. Our findings provide a mechanistic rationale for the use of safflower-derived polyacetylene glycosides as potential therapeutic agents against obesity.

Safflower (Carthamus tinctorius) is an annual herb belonging to the Compositae family; it has a history of use as a food colorant, dye, and medicine in oriental countries. LC-MS-UV-based chemical analysis of extract of the florets of C. tinctorius led to the isolation of two new C10-polyacetylene glycosides, (8Z)-decaene-4,6-diyne-1,10-diol-1-O-β-d-glucopyranoside (1) and (8S)-deca-4,6-diyne-1,8-diol-1-O-β-d-glucopyranoside (2), together with five known analogs (3–7). The structures of the new compounds were determined by using 1D and 2D NMR spectroscopic data and HR-MS data, as well as chemical transformations. Of compounds 1–7, compounds 2, 3, and 4 inhibited the adipogenesis of 3T3-L1 preadipocytes, whereas compounds 1 and 6 promoted adipogenesis. Compounds 2, 3, and 4 also prevented lipid accumulation through the suppression of the expression of lipogenic genes and the increase of the expression of lipolytic genes. Moreover, compounds 3 and 4 activated AMPK, which is known to facilitate lipid metabolism. Our findings provide a mechanistic rationale for the use of safflower-derived polyacetylene glycosides as potential therapeutic agents against obesity.

Carthamus tinctorius L. (Compositae; safflower or Hong Hua) has been used in Korean traditional medicine for maintaining the homeostasis of body circulation. Phytochemical investigation was performed on the florets of C. tinctorius by liquid chromatography–mass spectrometry (LC/MS), which afforded two dihydrophaseic acid glucosides (1 and 2). Isolated compounds were structurally confirmed using a combination of spectroscopic methods including 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectroscopy. Their absolute configurations were established by quantum chemical electronic circular dichroism calculations and enzymatic hydrolysis. The anti-adipogenesis activity of the isolated compounds was evaluated using 3T3-L1 preadipocytes. Treatment with the dihydrophaseic acid glucoside (1) during adipocyte differentiation prevented the accumulation of lipid droplets and reduced the expression of adipogenic genes, Fabp4 and Adipsin. However, compound 2 did not affect adipogenesis. Our study yielded a dihydrophaseic acid glucoside derived from C. tinctorius, which has potential advantages for treating obesity.

The global incidence of breast cancer has increased. However, there are many impediments to the development of safe and effective anticancer drugs. The aim of the present study was to evaluate the effect of aviculin isolated from Lespedeza cuneata (Dum. Cours.) G. Don. (Fabaceae) on MCF-7 human breast cancer cells and determine the underlying mechanism. Using the bioassay-guided isolation by water soluble tetrazolium salt (WST-1)-based Ez-Cytox assay, nine compounds (four lignan glycosides (1–4), three flavonoid glycosides (5–7), and two phenolic compounds (8 and 9)) were isolated from the ethyl acetate (EA) fraction of the L. cuneata methanolic extract. Of these, aviculin (2), a lignan glycoside, was the only compound that reduced metabolic activity on MCF-7 cells below 50% (IC50: 75.47 ± 2.23 μM). The underlying mechanism was analyzed using the annexin V Alexa Fluor 488 binding assay and Western blotting. Aviculin (2) was found to induce apoptotic cell death through the intrinsic apoptosis pathway, as indicated by the increased expression of initiator caspase-9, executioner caspase-7, and poly (ADP-ribose) polymerase (PARP). Aviculin (2)-induced apoptotic cell death was accompanied by an increase in the Bax/Bcl-2 ratio. These findings demonstrated that aviculin (2) could induce breast cancer cell apoptosis through the intrinsic apoptosis pathway, and it can therefore be considered an excellent candidate for herbal treatment of breast cancer.

Phallus luteus (Phallaceae), previously known as Dictyophora indusiata, is an edible and medicinal mushroom. As part of a continuing project to discover structurally and/or biologically novel natural products from wild mushrooms, we aimed to perform a chemical investigation of the methanol extract of P. luteus combined with a liquid chromatography–mass spectrometry-guided analysis coupled to an in-house UV spectral library. Two new sesquiterpenes, phallac acids A (1) and B (2), were isolated and determined. The chemical structure of the new natural products was unambiguously determined using a combination of 1D and 2D NMR and high-resolution electrospray ionization mass spectrometry data. To our knowledge, this is the first study to report linear sesquiterpene carboxylic acids from P. luteus. The new compounds were evaluated for α-glucosidase inhibitory activities where phallac acid B (2) showed α-glucosidase inhibitory potential (IC50 value of 94.89 ± 5.57 μM) compared with the standard acarbose (IC50 value of 26.23 ± 1.31 μM).

The global incidence of breast cancer has increased. However, there are many impediments to the development of safe and effective anticancer drugs. The aim of the present study was to evaluate the effect of aviculin isolated from Lespedeza cuneata (Dum. Cours.) G. Don. (Fabaceae) on MCF-7 human breast cancer cells and determine the underlying mechanism. Using the bioassay-guided isolation by water soluble tetrazolium salt (WST-1)-based Ez-Cytox assay, nine compounds (four lignan glycosides (1–4), three flavonoid glycosides (5–7), and two phenolic compounds (8 and 9)) were isolated from the ethyl acetate (EA) fraction of the L. cuneata methanolic extract. Of these, aviculin (2), a lignan glycoside, was the only compound that reduced metabolic activity on MCF-7 cells below 50% (IC50: 75.47 ± 2.23 μM). The underlying mechanism was analyzed using the annexin V Alexa Fluor 488 binding assay and Western blotting. Aviculin (2) was found to induce apoptotic cell death through the intrinsic apoptosis pathway, as indicated by the increased expression of initiator caspase-9, executioner caspase-7, and poly (ADP-ribose) polymerase (PARP). Aviculin (2)-induced apoptotic cell death was accompanied by an increase in the Bax/Bcl-2 ratio. These findings demonstrated that aviculin (2) could induce breast cancer cell apoptosis through the intrinsic apoptosis pathway, and it can therefore be considered an excellent candidate for herbal treatment of breast cancer.

Withania somnifera (Solanaceae), well-known as ‘Indian ginseng’ or ‘Ashwagandha’, is a medicinal plant that is used in Ayurvedic practice to promote good health and longevity. As part of an ongoing investigation for bioactive natural products with novel structures, we performed a phytochemical examination of the roots of W. somnifera employed with liquid chromatography–mass spectrometry (LC/MS)-based analysis. The chemical analysis of the methanol extract of W. somnifera roots using repeated column chromatography and high-performance liquid chromatography under the guidance of an LC/MS-based analysis resulted in a new withanolide, withasomniferol D (1). The structure of the newly isolated compound was elucidated by spectroscopic methods, including one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and high-resolution (HR) electrospray ionization (ESI) mass spectroscopy, and its absolute configuration was established by electronic circular dichroism (ECD) calculations. The anti-adipogenic activities of withasomniferol D (1) were evaluated using 3T3-L1 preadipocytes with Oil Red O staining and quantitative real-time polymerase chain reaction (qPCR). We found that withasomniferol D (1) inhibited adipogenesis and suppressed the enlargement of lipid droplets compared to the control. Additionally, the mRNA expression levels of adipocyte markers Fabp4 and Adipsin decreased noticeably following treatment with 25 μM of withasomniferol D (1). Taken together, these findings provide experimental evidence that withasomniferol D (1), isolated from W. somnifera, exhibits anti-adipogenic activity, supporting the potential application of this compound in the treatment of obesity and related metabolic diseases.

A new unique enolic glucoside of phenylpyruvic acid, carthamusuchuric acid (1), and five known phenolic compounds (2–6) were isolated from the florets of Carthamus tinctorius. The structure of the new compound was elucidated by extensive spectroscopic analyses using one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy, high-resolution electrospray ionization mass spectrometry, and enzymatic hydrolysis. The anti-adipogenic activity of compounds 1–6 was evaluated by staining lipid droplets in 3T3-L1 preadipocytes with Oil Red O and assessing mRNA expression of adipocyte markers. The results showed that compounds 2 and 4 inhibited the differentiation of 3T3-L1 preadipocytes to adipocytes.

Chunpoong is one of the most valuable cultivars of Panax ginseng C. A. MEYER, and is widely grown in Korea and China. Insertion/deletion (InDel) markers and single nucleotide polymorphism (SNP) markers are useful tools for marker-assisted selections. The SNP marker for determinate Chunpoong was previously developed from the nad7 gene of mtDNA by Wang et al. (2009) but was effective only on a limited range of cultivars. In this study, we studied the reasons for this limited application and developed new useful markers for application in Chunpoong-breeding programs. The new markers of InDel and SNP were designed in the major latex-like protein (MLP-like) gene which was highly expressed in 4-year-old Chunpoong expressed sequence tags (ESTs). To validate the marker in polymerase chain reaction (PCR), we used an InDel marker for identification of Chunpoong in the 70 Panax samples based on a double-blind test, and the success rate was 100%. For rapid and reliable assay of Chunpoong in numerous samples, we utilized an EvaGreen dye and melting curve method on real-time PCR. Furthermore, we designed an SNP marker that depended on the InDel region for more efficient detection of Chunpoong in real-time PCR. Compared with PCR-based assays, our Chunpoong SNP marker and real-time PCR assay offers a significant savings of time and labor in the analysis of large numbers of Chunpoong samples.

In order to investigate the effects of elicitors on the growth and ginsenoside biosynthesis of ginseng hairy roots, we treated Panax ginseng hairy root with various concentrations of Haliotidis concha according to different time course. Haliotidis concha supplement increased the biomass and ginsenoside accumulation at 10 ㎎/L concentration. The growth rate of hairy root under a lighter concentration was greater than hairy root treated with a denser concentration. The highest content and productivity of ginsenosides appeared at 2 weeks after the treatment of 10 ㎎/L Haliotidis concha. The gene expression of squalene synthase, squalene epoxidase, dammarenediol synthase, cycloartenol synthase, β-amyrin synthase in hairy roots of ginseng were examined by RT-PCR. The Haliotidis concha treatment resulted in the obvious accumulation of the mRNA of triterpene biosynthesis in Panax ginseng hairy root as compared with the control. In this study, Haliotidis concha acts as a kind of elicitor for the production of ginsenosides.

Terpene synthase plays a key role in biosynthesis of triterpene saponins (ginsenosides) and is intermediate in the biosynthesis of a number of secondary metabolites. A terpene synthase (PgTPS) cDNA was isolated and characterized from the root of Panax ginseng C.A. Meyer. The deduced amino acid sequence of PgTPS showed a similarity with A. deliciosa (AAX16121) 61%, V. vinifera (AAS66357) 61%, L hirsutum (AAG41891) 55%, M truncatula (AAV36464) 52%. And the segment of a terpene synthase gene was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). We studied expression of terpene synthase under stressful conditions like chilling, salt, UV, and heavy metal stress treatment. Expression of PgTPS was increased gradually after exposure to stresses such as chilling, salt, and UV illumination. But its transcription seems to be reduced by cadmium and copper treatment.

The characteristics of plantlets redifferentiated from calli of F1 hybrid between Panax ginseng and Panax quinquefolius were investigated. Growth of plantlets redifferentiated from F1 hybrid was superior to the plants redifferentiated from Korean ginseng. Stem color of plantlets redifferentiated from F1 hybrid was more purple than that from Korean ginseng and leaf color of the former was also greener than that of the latter. Chunpoong, Yunpoong and Seonweon which are belonged to Korean ginseng showed same PCR band(A), while American ginseng showed different PCR band (B) in Internal Transcribed Spacer (ITS) region. F1 hybrid exhibited both A and B PCR band which belonged to Korean ginseng and American ginseng, respectively. F1 hybrid calli and plantlets redifferentiated from F1 hybrid calli showed same PCR band with that of F1 hybrid plant in ITS region. Therefore it was confirmed that piantlets redifferentiated from F1 hybrid exhibited genetic stability in ITS region.

The expressed sequence tags (ESTs) referenced in this report are the first transcriptomes in a leaf from a half-shade ginseng plant. A cDNA library was constructed from samples of the leaves of 4-year-old Panax ginseng plants, which were cultured in a field. The 2,896 P. ginseng cDNA clones represent 1,576 unique sequences, consisting of 1,167 singletons and 409 contig sequences. BLAST comparisons of the cDNAs in GenBank's non-redundant databases revealed that 2,579 of the 2,896 cDNAs (89.1%) exhibited a high degree of sequence homology to genes from other organisms. The majority of the identified transcripts were found to be genes related with energy, metabolism, subcellular localization, and protein synthesis and transport. The chlorophyll a/b-binding protein ESTs in the ginseng leaf samples manifested a substantially higher level of expression than was observed in other plant leaves. The ESTs involved in ginsenoside biosynthesis were also identified and discussed.

DNA recombination required for mating type (mat1) switching in Schizosaccharomyces pombe is initiated by mat1 imprinting. The imprinting event is regulated by mat1 cis-acting elements and by several trans-acting factors, including swi1 (for switch), swi3, swi7, and sap1. swi1 and swi3 were previously shown to function in dictating unidirectional mat1 DNA replication by controlling replication fork movement around the mat1 region and, second, by pausing fork progression around the imprint site. With biochemical studies, we investigated whether the trans-acting factors function indirectly or directly by binding to the mat1 cis-acting sequences. First, we report the identification and DNA sequence of the swi3 gene. swi3 is not essential for viability, and, like the other factors, it exerts a stimulatory effect on imprinting. Second, we showed that only Swi1p and Swi3p interact to form a multiprotein complex and that complex formation did not require their binding to a DNA region defined by the smt-0 mutation. Third, we found that the Swi1p-Swi3p complex physically binds to a region around the imprint site where pausing of replication occurs. Fourth, the protein complex also interacted with the mat1-proximal polar terminator of replication (RTS1). These results suggest that the stimulatory effect of swi1 and swi3 on switching and imprinting occurs through interaction of the Swi1p-Swi3p complex with the mat1 regions.

Although most Ty1 elements in Saccharomyces cerevisiae are competent for retrotransposition, host defense genes can inhibit different steps of the Ty1 life cycle. Here, we demonstrate that Rad27, a structure-specific nuclease that plays an important role in DNA replication and genome stability, inhibits Ty1 at a posttranslational level. We have examined the effects of various rad27 mutations on Ty1 element retrotransposition and cDNA recombination, termed Ty1 mobility. The point mutations rad27-G67S, rad27-G240D, and rad27-E158D that cause defects in certain enzymatic activities in vitro result in variable increases in Ty1 mobility, ranging from 4- to 22-fold. The C-terminal frameshift mutation rad27-324 confers the maximum increase in Ty1 mobility (198-fold), unincorporated cDNA, and insertion at preferred target sites. The null mutation differs from the other rad27 alleles by increasing the frequency of multimeric Ty1 insertions and cDNA recombination with a genomic element. The rad27 mutants do not markedly alter the levels of Ty1 RNA or the TyA1-gag protein. However, there is an increase in the stability of unincorporated Ty1 cDNA in rad27-324 and the null mutant. Our results suggest that Rad27 inhibits Ty1 mobility by destabilizing unincorporated Ty1 cDNA and preventing the formation of Ty1 multimers.

Expressed sequence tags (ESTs) provide valuable tools that can be used to predict the genes involved in primary and secondary metabolite synthesis. To the best of our knowledge, ESTs have not yet been developed for Codonopsis. lanceolata, and therefore, the EST referenced in this report is the first transcript for C. lanceolata. A cDNA library was constructed using the roots of C. lanceolata plants that were grown in a field. The selected 881 cDNA clones were sequenced and processed with an EST pipeline, resulting in 636 unique sequences, including 517 singletons and 119 contig sequences. Using bioinformatics tools, 81% of the EST sequence was putatively annotated. Data for unique transcripts were mined from biological databases and functionally classified using gene ontology (GO), the Kyoto Encyclopedia of Genes and Genomes Orthology, KEGG pathway maps, and protein family. The GO-based analyses were examined in terms of biotic and abiotic stress response, transport, cellular component organization, biogenesis, and secondary metabolic processes. The KEGG-based analyses of most transcripts were sorted by carbohydrate metabolism, energy metabolism, and biosynthesis of secondary metabolites. Five randomly-selected putative genes were used for an expression study using various stresses such as salt, H(2)O(2), salicylic acid, and methyl jasmonic acid. Mined data were organized in "The Codonopsis EST Database" (www.bioherbs.khu.ac.kr/Codonopsis).

Eukaryotic genomes contain potentially unstable sequences whose rearrangement threatens genome structure and function. Here we show that certain mutant alleles of the nucleotide excision repair (NER)/TFIIH helicase genes RAD3 and SSL2 (RAD25) confer synthetic lethality and destabilize the Saccharomyces cerevisiae genome by increasing both short-sequence recombination and Ty1 retrotransposition. The rad3-G595R and ssl2-rtt mutations do not markedly alter Ty1 RNA or protein levels or target site specificity. However, these mutations cause an increase in the physical stability of broken DNA molecules and unincorporated Ty1 cDNA, which leads to higher levels of short-sequence recombination and Ty1 retrotransposition. Our results link components of the core NER/TFIIH complex with genome stability, homologous recombination, and host defense against Ty1 retrotransposition via a mechanism that involves DNA degradation.

Transcription factor UAF (upstream activation factor) is required for a high level of transcription, but not for basal transcription, of rDNA by RNA polymerase I (Pol I) in the yeast Saccharomyces cerevisiae. RRN9 encodes one of the UAF subunits. We have found that rrn9 deletion mutants grow extremely slowly but give rise to faster growing variants that can grow without intact Pol I, synthesizing rRNA by using RNA polymerase II (Pol II). This change is reversible and does not involve a simple mutation. The two alternative states, one suitable for rDNA transcription by Pol I and the other favoring rDNA transcription by Pol II, are heritable not only in mitosis, but also in meiosis. Thus, S. cerevisiae has an inherent ability to transcribe rDNA by Pol II, but this transcription activity is silenced in normal cells, and UAF plays a key role in this silencing by stabilizing the first state.

Like most eukaryotic rDNA promoters, the promoter for rDNA in Saccharomyces cerevisiae consists of two elements: a core element, which is essential, and an upstream element, which is not essential but is required for a high level of transcription. We have demonstrated that stimulation of transcription by the upstream element is mediated by a multiprotein transcription factor, UAF (upstream activation factor) which contains three proteins encoded by RRN5, RRN9, and RRN10 genes, respectively, and probably two additional uncharacterized proteins. The three genes were originally defined by mutants that show specific reduction in the transcription of rDNA. These genes were cloned and characterized. Epitope tagging of RRN5 (or RRN9), combined with immunoaffinity purification was used to purify UAF, which complemented all three (rrn5, rrn9, and rrn10) mutant extracts. Using rrn10 mutant extracts, a large stimulation by UAF was demonstrated for template containing both the core element and the upstream element but not for a template lacking the upstream element. In the absence of UAF, the mutant extracts showed the same weak transcriptional activity regardless of the presence or absence of the upstream element. We have also demonstrated that UAF alone makes a stable complex with the rDNA template, committing that template to transcription. Conversely, no such template commitment was observed with rrn10 extracts without UAF. By using a series of deletion templates, we have found that the region necessary for the stable binding of UAF corresponds roughly to the upstream element defined previously based on its ability to stimulate rDNA transcription. Differences between the yeast UAF and the previously studied metazoan UBF are discussed.

Loss of function of any one of three UPF genes prevents the accelerated decay of nonsense mRNAs in Saccharomyces cerevisiae. We report the identification and DNA sequence of UPF3, which is present in one nonessential copy on chromosome VII. Upf3 contains three putative nuclear localization signal sequences, suggesting that it may be located in a different compartment than the cytoplasmic Upf1 protein. Epitope-tagged Upf3 (FLAG-Upf3) does not cofractionate with polyribosomes or 80S ribosomal particles. Double disruptions of UPF1 and UPF3 affect nonsense mRNA decay in a manner indistinguishable from single disruptions. These results suggest that the Upf proteins perform related functions in a common pathway.

연구배경: 수면은 우리 건강에 필수적인 생리현상으로 적절한 수면을 취하지 못하면 여러 가지 건강에 악영향을 끼친다. 쉽게 잠이 오지 않거나 자주 깨고, 심하게 코를 골거나 자고 나서도 피로가 풀리지 않고 낮에 졸리는 증상 등은 부적절한 수면과 관계가 있다. 우리는 일차의료 환경에서도 흔한 이런 수면장애 증상에 ...

We showed previously that the increased rate of mRNA turnover associated with premature translational termination in the yeast Saccharomyces cerevisiae requires a functional UPF1 gene product. In this study, we show that the UPF1 gene codes for a 109-kDa primary translation product whose function is not essential for growth. The protein contains a potential zinc-dependent nucleic acid-binding domain and a nucleoside triphosphate-binding domain. A 300-amino-acid segment of the UPF1 protein is 36% identical to a segment of the yeast SEN1 protein, which is required for endonucleolytic processing of intron-containing pre-tRNAs. The same region is 32% identical to a segment of Mov-10, a mouse protein of unknown function. Dominant-negative upf1 mutations were isolated following in vitro mutagenesis of a plasmid containing the UPF1 gene. They mapped exclusively at conserved positions within the sequence element common to all three proteins, whereas the recessive upf1-2 mutation maps outside this region. The clustering of dominant-negative mutations suggests the presence of a functional domain in UPF1 that may be shared by all three proteins. We also identified upf mutations in three other genes designated UPF2, UPF3, and UPF4. When alleles of each gene were screened for effects on mRNA accumulation, we found that the recessive mutation upf3-1 causes increased accumulation of mRNA containing a premature stop codon. When mRNA half-lives were measured, we found that excess mRNA accumulation was due to mRNA stabilization. On the basis of these results, we suggest that the products of at least two genes, UPF1 and UPF3, are responsible for the accelerated rate of mRNA decay associated with premature translational termination.

Yeast RNA polymerase I contains 14 distinct polypeptides, including A43, a component of about 43 kDa. The corresponding gene, RPA43, encodes a 326-amino acid polypeptide matching the peptidic sequence of two tryptic fragments isolated from A43. Gene inactivation leads to a lethal phenotype that is rescued by a plasmid containing the 35S ribosomal RNA gene fused to the GAL7 promoter, which allows the synthesis of 35S rRNA by RNA polymerase II in the presence of galactose. A screening for mutants rescued by the presence of GAL7-35SrDNA identified a nonsense rpa43 allele truncating the protein at amino acid position 217. [3H]Uridine pulse labeling showed that this mutation abolishes 35S rRNA synthesis without significant effects on the synthesis of 5 S RNA and tRNAs. These properties establish that A43 is an essential component of RNA polymerase I. This highly hydrophilic phosphoprotein has a strongly acidic carboxyl-terminal domain, and shows no homology to entries in current sequence data banks, including all the genetically identified components of the other two yeast RNA polymerases. RPA43 mapped next to RPA190, encoding the largest subunit of polymerase I. These genes are divergently transcribed and may thus share upstream regulatory elements ensuring their co-regulation.