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At least 235 records · Page 13Linked to original sources
PubMed1994

Isolated P2 rRNA promoters of Escherichia coli are strong promoters that are subject to stringent control.

Ribosomal RNA synthesis in Escherichia coli is under stringent control. The seven rRNA operons are highly conserved and are each transcribed from two tandem promoters, P1 and P2, which are located about 120 base-pairs apart. In exponentially growing cells the majority of the transcripts are initiated at the P1 promoters. The P1 promoters are highly regulated, and are under stringent as well as growth rate controls. Here we demonstrate that transcription from the rrnA P1 promoter diminishes P2 expression. In the absence of P1, the P2 promoter acts as a rather strong promoter. Insertion of a transcription terminator between P1 and P2 eliminates the inhibition of P2 by P1, suggesting that the physical movement of RNA polymerase originating at P1 and progressing along the P2 promoter is necessary for the interference process to take place. Similarly to P1, the solitary P2 promoter is subject to stringent control.

Base Sequence↗
PubMed1976

Differential sensitivity to antibiotics of trp mRNA synthesis originating at the trp promoter and the lambda promoter.

Transcription of the Escherichia coli trp operon translocated into the early region of bacteriophage lambda can occur under the control of either of two promoters, the trp promoter on the lambda promoter (OL of N gene). (Imamato, F. and Tani, S. (1972) Nat. New Biol. 240, 172-175 and Ihara S. and Imamoto, F. (1976) Biochim. Biophys. Acta 432, 199-211). Trp mRNA synthesis originating at the trp promoter stopped when translation was blocked by chloramphenicol tetracycline erythromycin or puromycin. In contrast, trp mRNA synthesis originating at the lambda promoter was not affected by antibiotic action. This probably is a reflection of the properties of the "immediate early" class of genes of lambda, whose transcription in initiated at the PL. promoter and is not inhibited by the antibiotic. The inference is strengthened by comparable results with phage lambdatrpE-A (carrying an intact tro operon) and lambdatrpBA (carrying the operator-distal two genes but missing the trp promoter and operator). Thus it seems that either the promoter or other gene(s) located at the beginning of the operon, either at polymerase addition or because of some feature of the transcript, can determine a requirement for "coupling" of RNA polymerase to the translational machinery in vivo.

Chloramphenicol↗
PubMed1982

Promoter occlusion: transcription through a promoter may inhibit its activity.

Induction of prophage lambda inhibits the expression of the gal operon from its cognate promoters. The effect is observed only in cis, and is due to frequent transcription of the gal promoter region by RNA polymerase molecules initiating upstream at the prophage PL promoter. The frequency of transcription initiation at PL is some 30 times greater than that at the gal promoter, Pg1. PL is one of the strongest procaryotic promoters. This "promoter occlusion" is essentially complete when the distance between gal and PL is small (less than or equal to 10 kb); and when PL is fully active (that is, in the absence of the cl or cro repressors). We discuss the possibility that promoter occlusion at two lambda promoters, Pint and PR', might play a role in the sequential expression of viral functions.

Bacteriophage lambda↗
PubMed2006

CWAO of phenol using CeO2/gamma-Al2O3 with promoter--effectiveness of promoter addition and catalyst regeneration.

The effect of promoter addition on activity of CeO(2)/gamma-Al(2)O(3) was assessed via the CWAO of phenol. Adding Cu as the promoter rendered the most effective performance, followed by Mn, although the performance of Mn-promoted catalyst was inferior to CeO(2)/gamma-Al(2)O(3). Mineralization of phenol was effectively implemented at 160 degrees C using Cu-promoted catalyst (Ce15Cu5). Furthermore, at 180 degrees C this catalyst produced about 100% conversion of phenol (1h) and 95% removal of chemical oxygen demand (4h), higher than that of CeO(2)/gamma-Al(2)O(3). In contrast, Mn-promoted catalyst (Ce15Mn5) required a temperature above 220 degrees C for acceptable performance. Activity of re-used catalyst declined noticeably, due to deposits of carbonaceous compounds and leaching of metal ions. Regeneration with acetone rinsing after the first run was effective in recovering activity of Ce15Cu5, although after a second run further regeneration with acetone rinsing had only a moderate effect, due to residual carbonaceous deposits and the additive effect of leached metal species in each run. As an alternative to acetone, HCl or HNO(3) solution (0.01 M) was less effective at regenerating activity. In promoted catalysts, leached metal ions accounted for the majority of mineralization of phenol, while the solid catalyst played a dual role of initiator and terminator of free radicals. Despite a superior catalytic performance, leaching of Cu(2+) from the promoted catalyst caused a severe decline in activity and poses the problem of secondary pollution of treated wastewater. Therefore, addition of Cu, as well as other metal species, is unfavorable in promoting the CeO(2)/gamma-Al(2)O(3) catalyst.

Acetone↗
PubMed2004

Growth promotion and yield enhancement of peanut (Arachis hypogaea L.) by application of plant growth-promoting rhizobacteria.

Although plant growth-promoting rhizobacteria (PGPR) have been reported to influence plant growth, yield and nutrient uptake by an array of mechanisms, the specific traits by which PGPR promote plant growth, yield and nutrient uptake were limited to the expression of one or more of the traits expressed at a given environment of plant-microbe interaction. We selected nine different isolates of PGPR from a pool of 233 rhizobacterial isolates obtained from the peanut rhizosphere on the basis of ACC-deaminase activity. The nine isolates were selected, initially, on the basis of germinating seed bioassay in which the root length of the seedling was enhanced significantly over the untreated control. All the nine isolates were identified as Pseudomonas spp. Four of these isolates, viz. PGPR1, PGPR2, PGPR4 and PGPR7 (all fluorescent pseudomonads), were the best in producing siderophore and indole acetic acid (IAA). In addition to IAA and siderophore-producing attributes, Pseudomonas fluorescens PGPR1 also possessed the characters like tri-calcium phosphate solubilization, ammonification and inhibited Aspergillus niger and A. flavus in vitro. P. fluorescens PGPR2 differed from PGPR1 in the sense that it did not show ammonification. In addition to the traits exhibited by PGPR1, PGPR4 showed strong in vitro inhibition to Sclerotium rolfsii. The performances of these selected plant growth-promoting rhizobacterial isolates were repeatedly evaluated for 3 years in pot and field trials. Seed inoculation of these three isolates, viz. PGPR1, PGPR2 and PGPR4, resulted in a significantly higher pod yield than the control, in pots, during rainy and post-rainy seasons. The contents of nitrogen and phosphorus in soil, shoot and kernel were also enhanced significantly in treatments inoculated with these rhizobacterial isolates in pots during both the seasons. In the field trials, however, there was wide variation in the performance of the PGPR isolates in enhancing the growth and yield of peanut in different years. Plant growth-promoting fluorescent pseudomonad isolates, viz. PGPR1, PGPR2 and PGPR4, significantly enhanced pod yield (23-26%, 24-28% and 18-24%, respectively), haulm yield and nodule dry weight over the control in 3 years. Other attributes like root length, pod number, 100-kernel mass, shelling out-turn and nodule number were also enhanced. Seed bacterization with plant growth-promoting P. fluorescens isolates, viz. PGPR1, PGPR2 and PGPR4, suppressed the soil-borne fungal diseases like collar rot of peanut caused by A. niger and PGPR4 also suppressed stem rot caused by S. rolfsii. Studies on the growth patterns of PGPR isolates utilizing the seed leachate as the sole source of C and N indicated that PGPR4 isolate was the best in utilizing the seed leachate of peanut, cultivar JL24. Studies on the rhizosphere competence of the PGPR isolates, evaluated on the basis of spontaneous rifampicin resistance, indicated that PGPR7 was the best rhizoplane colonizer and PGPR1 was the best rhizosphere colonizer. Although the presence of growth-promoting traits in vitro does not guarantee that an isolate will be plant growth promoting in nature, results suggested that besides ACC-deaminase activity of the PGPR isolates, expression of one or more of the traits like suppression of phytopathogens, solubilization of tri-calcium phosphate, production of siderophore and/or nodulation promotion might have contributed to the enhancement of growth, yield and nutrient uptake of peanut.

Arachis↗
PubMed1983

Carbon starvation and growth rate-dependent regulation of the Escherichia coli ribosomal RNA promoters: differential control of dual promoters.

We studied the effects of carbon starvation and of varying the growth rate on the activity of each of the two tandem ribosomal RNA promoters from the rrnA operon of Escherichia coli. The cellular abundance of plasmid-encoded transcripts arising at promoters P1 and P2 and terminating at the ribosomal RNA terminator in promoter-terminator fusions, together with transcript turnover rates, was used to estimate promoter activities. The rate of synthesis of the P1-promoted transcript was found to increase exponentially with growth rate and predominate at fast growth rates. The activity of the downstream promoter (P2) changed only slightly at different growth rates. Upon carbon starvation, little or no activity of the upstream promoter was detectable, while P2 activity persisted. We interpret this to mean that the dual promoters are differentially regulated so as to have separate adaptive and maintenance functions. This model simplifies most features of rRNA regulation known in E. coli.

Escherichia coli↗
PubMed1989

Tumour-promoting and hyperplastic effects of phorbol and daphnane esters in CD-1 mouse skin and a synergistic effect of calcium ionophore with the non-promoting activator of protein kinase C, sapintoxin A.

Using an 18 week two-stage protocol we have compared the tumour-promoting properties of a range of phorbol and daphnane esters on female CD-1 mice. The induction of epidermal hyperplasia in this mouse strain by these compounds has also been assessed by comparison with the standard phorbol ester, 12-O-tetradecanoylphorbol-13-O-acetate (TPA). Two compounds, sapintoxin D (SAP D) and thymeleatoxin A (TA) (a daphnane structurally related to the second-stage promoter mezerein) were shown to be second-stage promoters using 5 nmol TPA as a first-stage promoter and 0.2 mumol 7,12-dimethylbenz[a]anthracene (DMBA) as initiator. Both compounds at a dose of 17 nmol were hyperplasiogenic. Two further derivatives, sapintoxin C (SAP C) and 4 alpha-sapinine (alpha-SAP) were inactive as promoters and hyperplastic agents. 4 alpha-sapinine, which prevents in vitro stimulation of protein kinase C (PKC), by 12-O-tetradecanoylphorbol-13-O-acetate (TPA) failed to inhibit significantly TPA-induced promotion and hyperplasia at a dose of 20 nmol and 100 nmol respectively. Sapintoxin A (SAP A), a potent activator of PKC, was neither a complete nor second-stage promoter at doses of up to 20 nmol. A series of in vivo and in vitro experiments which were carried out to determine the metabolic fate of this compound under experimental conditions showed that SAP A was not metabolized to any significant extent up to 48 h. When SAP A was co-administered with sub-hyperplastic doses of the calcium ionophore A23187 (5 micrograms and 10 micrograms) tumours appeared in a dose-dependent manner. This combination was also hyperplasiogenic in mouse skin. SAP A may be a useful probe for studying the involvement of PKC isozymes in tumour promotion and cell proliferation.

Animals↗
PubMed1990

Differential effects of renal carcinogens and tumor promoters on growth promotion and inhibition of gap junctional communication in two rat renal epithelial cell lines.

To evaluate the effects of renal carcinogens and tumor promoters on gap junctional intercellular communication (IC) and colony formation, two rat kidney epithelial cell lines were examined in vitro. The NRK-52E line was obtained from the American Type Culture Collection and the NK-4 line was established by us from male F344/NCr rats. The NRK-52E line was co-cultured on a confluent monolayer of lethally irradiated NRK-52E cells to determine colony-forming ability (cloning efficiency) and clonal expansion (average surface area of the colonies, SA) and the NK-4 line was cultured on collagen gel. Streptozotocin (STZ), a renal carcinogen, and trisodium nitrilotriacetate monohydrate (NTANa3), a renal carcinogen and tumor promoter, showed mild growth-enhancing effects on both cell lines, as determined by significant increases in SA, but not in cloning efficiency (CE). Sodium barbital (BBNa), a renal tumor promoter, had similar effects, while phenobarbital sodium (PBNa), a non-renal tumor promoter, lacked such activity. The effects of these compounds on gap junctional function were investigated by the Lucifer Yellow dye transfer microinjection assay using monolayers of NRK-52E and NK-4 cells. We found that STZ, NTANa3 and BBNa inhibited IC in NRK-52E cells, in accordance with their reported tumorigenic and/or tumor-promoting activity in vivo, while PBNa did not. Thus, we could present these findings in NRK-52E cells as an in vitro model to examine the potential tissue-specific effects of renal carcinogens and tumor promoters in vitro. We found, however, that other growth control mechanisms beside IC may play a role, because although the NK-4 line did not possess normal IC, the tumor promoters studied had identical growth-promoting effects on colony formation and expansion in both this cell line and the NRK-52E line.

Acetates↗
PubMed1988

Active oxygen induced DNA strand breakage and poly ADP-ribosylation in promotable and non-promotable JB6 mouse epidermal cells.

The evidence is convincing that oxidants and agents which induce a cellular pro-oxidant state can act as carcinogens, in particular as promoters and progressors. Importantly, infiltrated phagocytes represent a source of oxidants in inflamed tissues. We have studied the mechanism of the promotional action of active oxygen (AO) in mouse epidermal cells JB6 by comparing the non-promotable clone 30 to the promotable clone 41. In order to mimick AO released by phagocytes we used xanthine/xanthine oxidase as a source of extracellular superoxide and hydrogen peroxide. We found that AO stimulated the growth only of promotable clone 41 after an initial period of moderate inhibition while it was strongly cytostatic for non-promotable clone 30. Reasons for the higher cytostatic effect of AO on the non-promotable clone 30 were discovered when we measured DNA strand breakage and poly ADP-ribosylation of chromosomal proteins. At equal doses AO induced 4-5 times more DNA breaks in clone 30 in reactions which required iron--and probably also calcium--ions. The higher amount of DNA breakage in clone 30 was reflected in a higher extent of poly ADP-ribosylation. Excessive DNA breakage and poly ADP-ribosylation which causes the depletion of NAD and ATP may be responsible for the strong cytostatic effect of AO in clone 30. We conclude that differential resistance to the cytostatic/cytotoxic effect of AO in part determines the promotability of mouse epidermal cells JB6.

Animals↗
PubMed1986

Development of plant promoter expression vectors and their use for analysis of differential activity of nopaline synthase promoter in transformed tobacco cells.

I have developed promoter expression binary vectors based on the tumor-inducing plasmid of Agrobacterium tumefaciens to facilitate elucidation of plant gene regulation. Promoter activity can be determined by inserting DNA fragments into the multiple cloning sites of the vectors forming transcriptional and/or translational fusions between the cat structural gene and an inserted promoter region. The activity of the nopaline synthase (nos) promoter was demonstrated with the vector. However, three animal promoters tested with this system showed no measurable activity in plant cells. Examination of 40 independently derived transformed tissues revealed a 200-fold difference in the nos promoter activity. Furthermore, there is no apparent correlation between the neomycin phosphotransferase and chloramphenicol acetyltransferase activities, although both genes are closely linked and under control of identical nos promoters. These results indicate that vast differences in promoter activity of transferred genes can occur within the same cell, as well as in independently derived cell lines.

Journal Article↗
PubMed1993

Minimal role of enhanced cell proliferation in skin tumor promotion by mirex: a nonphorbol ester-type promoter.

Mirex, a chlorinated hydrocarbon previously used as a systemic insecticide and flame retardant, is a nongenotoxic hepatocarcinogen in both rats and mice. In liver, mirex induced biochemical responses and hyperplasia characteristic of increased cell proliferation, which is consistent with its role as a liver tumor promoter. We have recently shown that mirex is a potent nonphorbol ester-type skin tumor promoter in 7, 12-dimethylbenz[a]anthracene (DMBA)-initiated mice. However, unlike its effect in liver, a single topical application of mirex to skin does not induce the acute biochemical responses, such as increased epidermal DNA synthesis and ornithine decarboxylase activity, indicative of increased cell proliferation. Multiple topical applications of mirex over a 1 month period induced only a minimal increase in the number of epidermal nucleated cell layers, which contrasts with definitive hyperplasia induced by a comparable tumor-promoting dose of 12-O-tetradecanoylphorbol-13-acetate (TPA). Collectively, these data indicated that mirex is promoting through a novel mechanism. Further evidence that mirex promotes tumors through a mechanism distinct from that of the prototypical skin tumor promoter, TPA, was obtained by examining the effect of their simultaneous co-treatment. The co-application of mirex and TPA yielded a tumor multiplicity greater than the sum of the responses of each promoter individually. In summary, our results demonstrate that mirex, a carcinogenic and hyperplastic agent in liver, is also a very effective tumor promoter in mouse skin, but suggest that mirex operates via a novel mechanism in skin that may involve only a minimal role for enhanced cell proliferation.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

12-O-tetradecanoylphorbol-13-acetate promotion of transgenic mice expressing epidermal-targeted v-fos induces rasHA-activated papillomas and carcinomas without p53 mutation: association of v-fos expression with promotion and tumor autonomy.

Transgenic mice that expressed v-fos exclusively in the epidermis by means of a human keratin K1-based targeting vector (HK1.fos) developed preneoplastic epidermal hyperplasia and hyperkeratosis after long latency and an associated wound promotion stimulus. To assess the requirements for papilloma formation and malignant conversion and determine the sensitivity to a chemical promotion stimulus, HK1.fos mice were promoted with 12-O-tetradecanoylphorbol-13-acetate (TPA). HK1.fos mice were sensitive to TPA promotion but developed papillomas only after long latency (20-30 weeks of promotion) and in relatively few numbers per animal, suggesting the necessity of an additional genetic event prior to overt lesion formation. Consistent with this idea, at 60 weeks, on cessation of TPA promotion, these HK1.fos TPA-papillomas were found to be autonomous, TPA-independent tumors which persisted, grew larger, and converted to malignancy. Analysis of HK1.fos tumor RNA and DNA identified endogenous c-rasHa mutations at codons 12 and 61 in papillomas and carcinomas; however, no p53 tumor suppressor gene mutations were detected. These data indicate that epidermal expression of v-fos induces sensitivity to TPA promotion, but since additional genetic events, such as endogenous c-rasHa activation, appear to be required in tumorigenesis, v-fos may predominantly play a role in the mechanism of promotion to achieve papilloma autonomy and TPA independence. Furthermore, spontaneous malignant conversion in this model does not appear to involve mutations in the p53 tumor suppressor gene.

Animals↗
PubMed2002

Mouse alpha1(I)-collagen promoter is the best known promoter to drive efficient Cre recombinase expression in osteoblast.

Cell- and time-specific gene inactivation should enhance our knowledge of bone biology. Implementation of this technique requires construction of transgenic mouse lines expressing Cre recombinase in osteoblasts, the bone forming cell. We tested several promoter fragments for their ability to drive efficient Cre expression in osteoblasts. In the first mouse transgenic line, the Cre gene was placed under the control of the 2.3-kb proximal fragment of the alpha1(I)-collagen promoter, which is expressed at high levels in osteoblasts throughout their differentiation. Transgenic mice expressing this transgene in bone were bred with the ROSA26 reporter (R26R) strain in which the ROSA26 locus is targeted with a conditional LacZ reporter cassette. In R26R mice, Cre expression and subsequent Cre-mediated recombination lead to expression of the LacZ reporter gene, an event that can be monitored by LacZ staining. LacZ staining was detected in virtually all osteoblasts of alpha1(I)-Cre;R26R mice indicating that homologous recombination occurred in these cells. No other cell type stained blue. In the second line studied, the 1.3-kb fragment of osteocalcin gene 2 (OG2) promoter, which is active in differentiated osteoblasts, was used to drive Cre expression. OG2-Cre mice expressed Cre specifically in bone. However, cross of OG2-Cre mice with R26R mice did not lead to any detectable LacZ staining in osteoblasts. Lastly, we tested a more active artificial promoter derived from the OG2 promoter. The artificial OG2-Cre transgene was expressed by reverse transcriptase-polymerase chain reaction in cartilage and bone samples. After cross of the artificial OG2-Cre mice with R26R mice, we detected a LacZ staining in articular chondrocytes but not in osteoblasts. Our data suggest that the only promoter able to drive Cre expression at a level sufficient to induce recombination in osteoblasts is the alpha1(I)-collagen promoter.

Animals↗
PubMed1998

RNA polymerase mutants that destabilize RNA polymerase-promoter complexes alter NTP-sensing by rrn P1 promoters.

Mutations in Escherichia coli rpoB or rpoC, selected for the ability to confer prototrophy on relA spoT strains, were found to affect transcription from rrn P1 promoters. Two mutant strains (beta RH454 and beta' delta 215-220) reduced transcription of rrn P1 core promoter-lacZ fusions but not of control promoter-lacZ fusions. Purified mutant RNAPs formed complexes with rrn P1 promoters that were much less stable than those formed by wild-type RNAP and required high concentrations of the initiating NTP for efficient rrn P1 transcription. The instability of the rrn P1 core promoter complexes with the mutant RNAPs and their altered regulatory properties support a recently proposed model for the control of rRNA transcription by changing concentrations of the initiating NTPs. We further suggest that destabilization of promoter complexes by the mutant RNAPs mimics effects of ppGpp, decreasing or increasing transcription depending on the kinetic properties of the specific promoter.

Adenosine Triphosphate↗
PubMed1989

In vivo selected promoter and ribosome binding site up-mutations: demonstration that the Escherichia coli bla promoter and a Shine-Dalgarno region with low complementarity to the 16 S ribosomal RNA function in Bacillus subtilis.

We have constructed a plasmid, pQS1, in which a mouse dihydrofolate reductase (5,6,7,8-tetrahydrofolate:NADP:oxidoreductase; EC 1.5.1.3; DHFR) cDNA is inserted in the unique PstI site of a gram-positive/gram-negative shuttle vector derived from pBR322. The cDNA is expressed under the control of the bla promoter, which, like most gram-negative bacterial genes, is considered not to be expressed in Bacillus subtilis, and its coding sequence is translated from a polycistronic message. We have selected in vivo and studied, in Escherichia coli and B. subtilis, expression mutants with promoter and ribosome binding site sequence mutations. One promoter mutation changes the third nucleotide of the -35 region from a C to a G. As expected, this substitution results in increased transcriptional activity in E. coli. In B. subtilis, this mutation induces the accumulation not only of a low but significant amount of dhfr mRNA but also of DHFR, demonstrating that binding strengths with a free energy as low as -9.4 kcal/mol are sufficient to promote ribosome binding in B. subtilis. The association of the promoter mutation (C-G) with a mutation which creates a strong B. subtilis ribosome binding site (-21 kcal/mol) results in the accumulation of a large amount of dhfr mRNA. This demonstrates the importance of having an efficient ribosome binding site in the evaluation of promoter function: for example, with this strong ribosome binding site we can show that the wild-type bla promoter is recognized by the B. subtilis transcription machinery.

Animals↗
PubMed1995

Nuclear proteins that interact with the beta maj globin promoter start to accumulate in MEL cells within 12 hours of induction and RNA copies of the promoter successfully compete their binding in vitro.

The induction of differentiation in mouse erythroleukemia (MEL) cells by dimethylsulfoxide (DMSO) is characterized by increased transcription of globin genes. We have determined that DMSO treated cells increase the levels of nuclear factors capable of overall interactions with the beta maj globin promoter during the initial 24 h post induction, as measured by gel mobility analysis. Two unprocessed beta maj globin mRNA precursors, which are present in MEL cell nuclei early in differentiation, were previously shown to contain the 5' promoter flanking region, and thereby provided the nucleus with a pool of regulatory sequences in multiple RNA copies. We have studied the effect of RNA copies of the promoter region on binding interactions between DNA sequences of the beta maj globin promoter and nuclear factors that interact with these sequences. The promoter region RNA transcripts competed effectively for DNA binding proteins in vitro, while the antisense RNA from the same region did not. The most pronounced competition was observed with proteins from 12 h after DMSO induction, when the concentration of the DNA binding proteins was still increasing. Since the 'upstream' transcripts predominate at 12 h after DMSO induction, these results indicate that the promoter region transcripts may influence the equilibrium of binding between the beta maj globin promoter and the nuclear factors that bind to this region during DMSO induction.

Animals↗
PubMed2005

Transgene silencing may be mediated by aberrant sense promoter sequence transcripts generated from cryptic promoters.

To investigate whether silencing of a T-DNA-carried nptII gene in five single-copy transgenic Arabidopsis lines might be due to position effects, genomic DNA flanking the insertions was analysed for gene density, GC content, presence of short repeats and transposable elements, i.e. factors suggested to promote silencing. No single, common factor could explain the observed silencing. However, in two lines, a transcript covering the nos promoter driving the nptII gene was detected. In sibling sublines with approximately 100% silencing, the nos promoter was heavily methylated. In silico analysis suggested the presence of cryptic core promoters upstream of the nos promoter, in one case in the plant DNA and in the other in a short inverted TDNA region. These fragments were able to drive reporter gene expression in transgenic Arabidopsis plants. Our results indicate that methylation and silencing of transgenic promoters may be mediated by aberrant RNA transcribed from cryptic promoters at the transgene insertion site.

Arabidopsis↗
PubMed2002

MET3 promoter: a tightly regulated promoter and its application in construction of conditional lethal strain.

The beta-galactosidase activity driven by MET3 promoter was assayed in the absence of methionine and in the presence of different concentration of methionine in medium. To compare its activity with GAL1 promoter and the data reported by Mumburg about MET25 promoter, the MET3 promoter was a weak but tightly controlled promoter. Its successful application in the construction of methionine-sensitive tri-mutant ( cln1 Delta cln2 Delta pho85 Delta) demonstrated that the MET3 promoter is a useful promoter in construction of conditional lethal strain and heterologous expression in Saccharomyces cerevisiae.

Cloning, Molecular↗