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At least 181 records · Page 10Linked to original sources
PubMed1997

Upstream NF-kappaB site is required for the maximal expression of mouse inducible nitric oxide synthase gene in interferon-gamma plus lipopolysaccharide-induced RAW 264.7 macrophages.

Transient transfection assays with various deletion mutants of the mouse inducible nitric oxide synthase (iNOS) promoter linked to a CAT reporter gene demonstrated that, besides the downstream NF-kappaB site, the region from -973 to -925 which contains a potential binding site for NF-kappaB (upstream NF-kappaB site) also mediated lipopolysaccharide (LPS)-inducibility in mouse macrophage cell line RAW 264.7. Site-specific mutation of three conserved nucleotides within the upstream NF-kappaB site abolished additional induction by LPS as well as maximal expression of iNOS by IFN-gamma plus LPS. In contrast, site-specific mutation of the downstream NF-kappaB site caused almost all reduction in expression of the reporter gene by LPS or LPS plus IFN-gamma. Electrophoretic mobility shift assays with the two NF-kappaB sites showed LPS-induced NF-kappaB binding to both probes and its higher affinity to the upstream NF-kappaB site. Taken together, these suggest that the upstream NF-kappaB site having enhancer function, besides the downstream NF-kappaB site as a core promoter, is essential for maximal expression of the iNOS gene.

Animals↗
PubMed1994

Short upstream sequences associated with the muscle-specific expression of an actin gene in ascidian embryos.

The HrMA4 alpha gene for an embryonic muscle actin of the ascidian Halocynthia roretzi is activated at the gastrula stage in differentiating muscle cells exclusively. The 5' upstream region close to the transcription start site of HrMA4 alpha contains several consensus sequences, which include a TATA box at -30, and E-box at -71, a CArG box at -116, and a cluster of three E-boxes between -150 and -190. When deletion constructs of this region, fused with the bacterial gene for beta-galactosidase (lac-Z), were microinjected into fertilized eggs, the reporter gene was expressed in muscle cells of tailbud embryos. Analyses of the deletion constructs suggested that the 103-bp upstream region is sufficient for the appropriate expression of the gene. However, beta-gal activity was very rarely detectable in the case of 82-bp upstream region and no activity was detected in the case of 72-bp upstream region. Mutations in the proximal E-box sequence did not disturb the muscle-specific expression of the reporter gene. These results suggest that rather short sequences between nucleotides -103 and -72 from the transcription start site are associated with the specific expression of HrMA4 alpha.

Actins↗
PubMed1995

Analysis of neural-responsive myogenin upstream sequences by myoblast implantation.

The expression of myogenin is suppressed during innervation and has been implicated in determining properties of skeletal muscle which are regulated by electrical activity. We previously reported that transcription driven by 3700 bp of the mouse myogenin upstream sequence (MYG3700) is activated by denervation in transgenic mice (Nucleic Acids Res. 21, 5684-5693, 1993). To extend our investigation of the activity dependence of the myogenin promoter, we have utilized myoblast implantation as a novel approach to in vivo reporter analysis. Myoblasts for hindlimb injections were generated by stable transfection of chloramphenicol acetyltransferase (CAT) reporters into a beta-galactosidase-expressing line of C2 cells. In vitro characterization of stable myoblast clones carrying myogenin-CAT deletion constructs revealed that while the proximal myogenin 5'-flanking sequence confers myotube specificity, high-level expression requires a region upstream (-335 to -1102) which depends on chromosomal integration for its function. For analysis by implantation, incorporation of injected myoblasts into existing myofibers was confirmed by histochemical staining. Using clonal myoblasts harboring nicotinic receptor alpha-subunit (alpha 800) and myosin light chain receptors as positive and negative controls, respectively, for denervation responsiveness, we determined that the nuclei of injected myoblasts are susceptible to regulatory signals imposed by nerve-induced electrical activity of the myofiber into which they incorporate. In in vivo analysis of myogenin upstream sequence by implantation, CAT activities of MYG3700 and MYG1565 reporters in injected limbs increased up to fourfold within 4 days after denervation, whereas the activities of MYG1102 and MYG335 were unchanged. By 10 days after denervation, all myogenin reporters displayed denervation responsiveness. These implantation data suggest an early phase of denervation activation, one that is mediated by control elements residing within -1102 to -1565 of the myogenin upstream sequence. Thus, the combined analyses of stable reporter myoblast lines in vitro and in vivo by implantation provide an efficient means of evaluating regulatory regions for high-level expression and neural modulation of muscle gene transcription.

Animals↗
PubMed1993

The structure of the human dihydrolipoamide dehydrogenase gene (DLD) and its upstream elements.

The structural organization of the gene for the E3 subunit of the human alpha-ketoacid dehydrogenase complexes, dihydrolipoamide dehydrogenase (DLD), and its upstream elements have been determined by restriction endonuclease mapping and DNA sequence analysis of overlapping genomic clones. The gene is approximately 20 kb long. It contains 14 exons ranging in size from 69 to 780 bp and 13 introns ranging in size from 93 bp to 7.0 kb. All splice donor and acceptor sites conform to the GT/AG rule. The 5' ends of mRNA transcripts upstream from the translation initiation codon were determined by primer extension assay. A "CAAT box"-like sequence is present at 39 bp upstream of the presumptive cap site and the 5' flanking region has been sequenced up to 2.0 kb upstream. There are several sequences compatible with presumptive promoter elements, including an Sp1 binding site, a nuclear respiratory factor 1 site, two cyclic AMP response element binding sites, and a possible negative response element present in the insulin promoter. A 313-bp segment from -2076 to -1763 is 89% homologous to a recently described pTR5 repetitive element found in the human genome.

Amino Acid Sequence↗
PubMed1995

Repression of vertebrate RNA polymerase III transcription by DNA binding proteins located upstream from the transcription start site.

Derivatives of yeast tRNA and Xenopus tRNA and 5 S RNA genes have been constructed in which natural 5' flanking sequences have been replaced by the binding sites for either the yeast transcription activator protein GCN4 or the three amino-terminal zinc fingers of the Xenopus factor TFIIA (zf1-3). The binding sites for these proteins have been placed at various distances upstream from the start site for transcription initiation in the parent genes. Each of these plasmid DNAs is actively transcribed in both an unfractionated transcription extract prepared from unfertilized Xenopus eggs and in a reconstituted Xenopus transcription system. Binding of the test proteins to plasmid DNAs harboring the cognate binding sites severely represses transcription when these binding sites are located less than approximately 40 base-pairs upstream from the transcription start site. The DNA-binding proteins are without effect on the transcription of plasmids lacking binding sites or when the binding sites are located further upstream. Assembly of DNA templates into a complete transcription complex prior to addition of the DNA-binding proteins prevents repression. Proteins present in a fraction containing TFIIIB are necessary for this reversal of repression. These data suggest that vertebrate TFIIIB binds upstream from class III genes and this binding can be prevented by occlusion of the TFIIIB binding site by the test proteins GCN4 and zf1-3.

Animals↗
PubMed1997

In vivo analyses of upstream promoter sequence elements in the 5 S rRNA gene from Saccharomyces cerevisiae.

Upstream promoter elements of the Saccharomyces cerevisiae 5 S rRNA gene have been characterized by genomic DNase I "footprinting" and by in vivo mutational analyses using base substitutions and deletions. A high copy shuttle-vector was used to efficiently express the mutant 5 S rRNA genes in vivo and a structural mutation in the 5 S rRNA, which was previously shown to be functionally neutral but easily detected by gel electrophoresis, allowed for an accurate measure of gene expression. The results provide direct evidence for upstream regulatory elements which confirms a start site element (sse) from -1 to -8 and identifies a new independent upstream promoter element (upe) centered from about -17 to -20. In contrast to previous reports with reconstituted systems, both elements dramatically affect the efficiency of gene expression and suggest that the saturated conditions which are used in reconstituted studies mask sequence dependence; a dependency that could be physiologically significant and play a role in the regulation of 5 S rRNA expression. The footprint analyses support an extended region of protein interaction as recently observed in reconstituted systems but again provide evidence of significant structural rearrangements when the upstream sequence is changed.

Base Sequence↗
PubMed1992

The nuclear factor SP8BF binds to the 5'-upstream regions of three different genes coding for major proteins of sweet potato tuberous roots.

Sporamin and beta-amylase are two major proteins of tuberous roots of sweet potato, and expression of genes coding for sporamin and beta-amylase is induced concomitantly in leaves with the petioles attached by exogenous supply of sucrose or polygalacturonic acid. We have used a DNase I footprinting assay to characterize nuclear factors that bind to the 5'-upstream regions of gSPO-A1, gSPO-B1 and g beta-Amy genes that encode A-type sporamin, B-type sporamin and the subunit of beta-amylase, respectively. Nuclear extracts from sucrose-treated petioles protected a region around -155 relative to the transcription start site of gSPO-A1 and a region around -880 of g beta-Amy from DNase I digestion on both strands. These two protected regions both contained the sequence ACTGTGTA, designated SP8a, in opposite orientation with respect to the direction of transcription. A gel mobility shift assay with SP8a oligonucleotide and competition experiments indicated that a common factor SP8BF binds to the SP8a sequence in gSPO-A1 and g beta-Amy. Binding of SP8BF to the SP8a oligonucleotide was abolished by mutation within the SP8a sequence. Fragments of the 5'-upstream region of gSPO-B1 also competed for the binding of SP8BF to the SP8a oligonucleotide, and the DNase I footprinting assay revealed three binding sites for SP8BF in the 5'-upstream region of gSPO-B1. These three sites in gSPO-B1 all contained the sequence TACTATT, designated SP8b, which shared 4 nucleotides at identical positions with the SP8a sequence. An inverted repeat of the SP8b sequence was also present at one protected site in the 5'-upstream region of g beta-Amy. In addition to sucrose-treated petioles, SP8BF activity was also present in tuberous roots and untreated fresh petioles of sweet potato. Furthermore, the activity was also detected in stems of tobacco plantlets, suggesting that SP8BF is an ubiquitous factor.

Base Sequence↗
PubMed1991

Positive and negative elements upstream of the meiosis-specific glucoamylase gene in Saccharomyces cerevisiae.

The SGA1 gene encoding glucoamylase is specifically expressed late in meiotic development of the yeast Saccharomyces cerevisiae. We found that accumulation of both enzyme activity and transcripts was regulated negatively by both nutritional signals and a haploid-specific negative regulator gene of meiosis. RME1, and positively by the inducer genes for meiosis, IME1 and IME2. To study the role of sequences upstream of the SGA1 gene in its expression and regulation, we generated internal deletions in the 5' non-coding region of the gene and chimeric genes with portions of the upstream sequence inserted into a reporter gene. By analyzing the expression of these genes, we have identified both a 19 bp upstream activation sequence (UAS) and a 49 bp negatively regulating element (NRE). The UAS activated transcription with no requirement for heterozygosity at the mating-type locus, but this activation was still under negative control by nutrients. The NRE showed no UAS-like activity but conferred IME2-dependent (or meiosis-specific) expression on a heterologous promoter. These results suggest that meiosis-specific expression of the SGA1 gene is established by a regulatory hierarchy including positive and negative factors, the actions of which are mediated through the two separate upstream regulatory elements, UAS and NRE, respectively. Also, that two independently acting cascades exist for the regulation of SGA1 expression: one transduces both the mating-type and nutritional signals and includes the IME2 product, which acts to relieve the repression through NRE; and another transduces only the nutritional signal independently of the above pathway and inhibits positive factors acting on UAS.

Autoradiography↗
PubMed1992

Analysis of an upstream regulatory sequence required for activation of the regulatory gene xylS in xylene metabolism directed by the TOL plasmid of Pseudomonas putida.

Transcription from the promoter of a positive regulatory gene, xylS, on the TOL plasmid of Pseudomonas putida is activated by another positive regulator, XylR, in the presence of m-xylene and is dependent on RNA polymerase containing the NtrA protein (sigma 54). Deletion analysis of the upstream region of the xylS gene revealed an upstream regulatory sequence (URS), located between 145 and 188 bp upstream from the transcription start site. The URS is active in either orientation and can be placed 3.9 kb further upstream without loss of activity. Dependence of activation on helical periodicity was observed in the region between the URS and the promoter of the xylS gene, suggesting DNA loop formation between these two sites, which are located about 100 bp apart. The expression of xylR was autogenously repressed by XylR protein. This autogenous repression is decreased in an NtrA- background, irrespective of the presence of the xylS promoter in cis, indicating that NtrA protein, or NtrA-containing RNA polymerase that is not bound to the xylS promoter, is involved in the binding of XylR protein to the URS.

Bacterial Proteins↗
PubMed1994

Characterization of the chromatin structure in the upstream region of the chicken alpha-globin gene domain.

The distribution of DNase I hypersensitive sites upstream of the chicken alpha-globin gene cluster was studied. A group of hypersensitive sites with a complex pattern of tissue specificity, including erythroid-specific elements, was found at a distance of 11.5-14.5 kb upstream of the pi gene, the first gene in the cluster. The observations indicate that this area, located upstream of the block of AT-rich sequences and MAR sites (at -8 kb) and upstream of the site of permanent DNA attachment to the nuclear matrix (-3 kb), still belongs to the domain of the alpha-globin genes.

Animals↗
PubMed1987

Positional requirements for the function of nif-specific upstream activator sequences.

The upstream activator sequence (UAS) found in Klebsiella pneumoniae nif promoters and required for the activation of transcription by nifA, is absent from the nifF-nifL intergenic region, but is present downstream from the nifLA transcription start at +59. To determine whether nif upstream activator sequences can function in a 3' position, the nifH UAS was cloned downstream from the NifH transcription start, but no activation of transcription by nifA dependent upon the UAS in its 3' location could be detected. A mild repressive effect was detectable when the nifH UAS was placed downstream of the nifH promoter, but not when the cat promoter was substituted for the nifLA promoter upstream from the motif at +59 described above. However, deletion analysis showed that the UAS motif located downstream of the nifLA promoter has a role in transcription from the nifF promoter, although it is situated at position -263 with respect to the nifF transcription start, about 100 bp further upstream than previously described occurrences of the activator sequence.

Genes, Bacterial↗
PubMed1990

Promoter function and in situ protein/DNA interactions upstream of the yeast HSP90 heat shock genes.

We have mapped in vivo protein/DNA interactions within the upstream regulatory regions of the two yeast HSP90 genes, and have begun mutagenizing footprinted sequences in an effort to identify the cis-acting determinants of heat shock transcription. Genomic footprinting of the HSP82 promotor using chemical and enzymatic nucleases reveals that irrespective of transcriptional state, the most proximal of three heat shock elements, HSE1, is occupied along both sugar-phosphate backbones as well as within its major groove, while the TATA box is bound along both sugar-phosphate backbones. Distorted DNA structure is associated with each constitutively bound factor: protein binding to HSE1 appears to induce a local A-form-like helical conformation, whereas occupancy of the TATA box is associated with strand-specific nuclease hypersensitivity of an adjacent polypurine tract. In situ mutagenesis experiments indicate that HSE1 is absolutely required for both basal and induced expression, and that basal transcription can be preferentially abolished by point mutations within this sequence. In contrast, point mutations within the TATA element have the reverse effect, as induced transcription is more significantly affected. Similar to HSE1 point mutants, we have found that basal transcription is preferentially repressed by an HMRE silencer element when it is transplaced approximately 1 kb upstream of the HSP82 start site. Finally, a complementary footprinting analysis of the upstream region of the constitutively expressed HSC82 gene reveals the presence of three discrete protein complexes. These map to the TATA box, the promotor-distal heat shock element, C.HSE1, and a novel sequence upstream of C. HSE1, suggesting that the 10-fold higher basal transcription of HSC82 stems, at least in part, from a non-HSE-binding factor.

Base Sequence↗
PubMed1994

Analysis of a translational enhancer upstream from the coat protein open reading frame of potato virus S.

Evidence has suggested that the subgenomic RNA of the carlavirus potato virus S is an efficient message for the coat protein, even though evidence suggests it is uncapped at its 5' terminus. We have investigated the effect of the upstream region of the coat protein gene of potato virus S on the level of reporter gene expression in vitro. The region of 101 nucleotides upstream of the coat protein, designated VTE (viral translational enhancer) was found to increase levels of translation in comparison to a synthetic leader when linked to the beta-glucuronidase (GUS) reporter gene in vitro in rabbit reticulocyte and wheat germ lysate. VTE was also able to increase translation of the reporter gene luciferase (LUC) in vitro above the levels obtained for both a synthetic leader and a leader obtained from a plant gene isolated from Arabidopsis thaliana. The level of enhancement was evident with both capped and uncapped transcripts. When the VTE sequence was deleted to 20 nucleotides of the upstream region, thus removing the nucleotide block homologous among carlaviruses, the ability to enhance levels of translation was removed. In vitro translation studies indicated that the translational enhancement activity of VTE was at least partially cap independent. Translation of VTE linked to reporter genes in the presence of cap analogue was relatively unaffected whereas synthetic leader and a plant leader constructs were both more sensitive. In vitro competition analysis revealed that when short RNA transcripts representing the 101 nucleotides of VTE were added in trans to functional VTE leader LUC constructs there was a marked decrease in the level of translation when compared with a synthetic leader added in trans. These results suggest that the upstream region of the coat protein ORF of potato virus S promotes translation in a cap-independent manner that may involve the binding of proteins and/or ribosomes to the 101 nucleotides of the VTE sequence.

Animals↗
PubMed1995

Immediate upstream promoter regions required for neurospecific expression of SNAP-25.

The promoter structure and regulation of Snap, a gene encoding the presynaptic t-SNARE SNAP-25 implicated in synaptic vesicle docking and fusion, was studied. Transcription start-site analysis revealed two major start sites located 42 nucleotides apart. Nucleotide sequence of a promoter region 2073 nucleotides upstream of the first transcription site contains three AP-1, one CRE sequence, and three Sp1-like sites close to the TATA box. Further upstream of these sites two TG repeats were found. The ability of regions within the 5' upstream sequence to promote basal neural-specific expression in tissue culture cells was evaluated using a series of constructs containing both Snap gene start sites with progressively restricted 5' sequence linked to the chloramphenicol acetyl transferase (CAT) reporter gene. CAT expression was maximal in neuron-like undifferentiated ND7 and PC12 cells transfected with constructs containing Snap sequences up to 127 bp from the start site. In contrast, nonneuronal fibroblast cell lines did not express significant amounts of CAT, suggesting that this short 127-bp sequence is sufficient to drive neural specific expression of SNAP-25. Band shift analysis of oligonucleotides spanning from -127 to -41 bp of the Snap promoter revealed three distinct DNA-protein complexes generated by brain nuclear extracts and one by liver nuclear extracts, indicating that transcription factors that bind to this 86-bp sequence located just upstream of the TATA box are involved in regulation of basal neurospecific expression of this gene.

Animals↗
PubMed2001

Toxic effects of wastewaters collected at upstream and downstream sites of a purification station in cultures of rainbow trout hepatocytes.

The toxic effects of wastewater samples, collected in December 1998, from upstream (U) and downstream (D) sites of the purification station of the town of Nice (South-East France on the coast of the Mediterranean Sea) were assessed undiluted and at various dilutions (75%, 50%, and 25% of collected water sample), on trout hepatocyte cultures treated for 48 or 72 h. Chemical contamination (PCBs, PAHs, Cd, Cu, Pb, and Zn) was also evaluated by chemical analysis. The water samples from the upstream site were more cytotoxic than those from the downstream site. The induction of CYP1A enzyme and metallothioneins (MTs) were selected as specific indicators of exposure to organic contaminants and metals, respectively. CYP1A-related EROD activity as well as protein expression were found to be greatly induced after 72 h exposure of the hepatocytes to the undiluted water samples (U(100%) and D(100%)), but CYP1A1 mRNA was significantly overexpressed only by samples from the upstream site. Maximal MT levels were reached after 48 h of treatment with the least concentrated water samples (U(25%) and D(25%)). Glutathione S-transferase (GST) activities were similarly increased under the same conditions. On the other hand, there was no significant glutathione peroxidase (GPx) activity response. Induction of apoptosis was analyzed by using as markers both the fragmentation of the nuclear DNA into oligonucleosomal-length fragments recognized as a "DNA ladder" and the activation of DEVD (Asp-Glu-Val-Asp)-dependent protease considered as the central mediator of programmed cell death. Significant DNA cleavage was only detectable after 72-h exposure to the most concentrated water samples from upstream sites (U(75%) and U(100%)). DEVD-dependent protease activities were significantly increased, mainly in cells exposed to U(75%) and D(25%) for 72 h. In addition, pollution-related DNA damage assessed by using the Comet assay was approximatively 1.5 times greater than that of the control level with the undiluted water samples U(100%) and D(100%), after 72-h and 48-h exposure, respectively. The present study shows that such a multibiomarker-based approach could provide complementary information, for aquatic pollution monitoring, about the early biochemical effects in cells exposed to complex chemical pollution and could be considered as early warning systems to aquatic pollution.

Animals↗
PubMed1993

Effect of stenosis inlet geometry on shear rates of blood flow in the upstream region.

Abnormal shear rates of blood flow have been implicated in the processes of thrombosis, atherosclerosis, and restenosis after angioplasty. However, no study has quantitated the effect of stenosis inlet geometry on the shear rates in the region upstream to the stenosis. To quantitate this effect, we measured the velocity profiles of blood flow at Reynolds numbers 175 and 350 upstream to different axisymmetric model stenoses in an excised canine aorta. Two 40% and two 75% stenoses were tested, one each with a 45-degree inlet angulation and one each with a 90-degree angulation. For the velocity measurements we used a specially developed external single-channel Doppler ultrasound system capable of resolving blood flow velocity at 91 microns radial intervals across the aorta. We found that increasing the severity of stenosis narrowing and angulation resulted in a significant decrease in shear rate at the endothelial surface (40%/45-degree stenosis: 189 +/- 46 sec-1 vs 75%/90-degree stenosis: 49 +/- 12 sec-1 at Reynolds number 350; p < 0.002) and a significant increase in the maximum shear rate within the vessel lumen (189 +/- 46 sec-1 vs 295 +/- 8 sec-1, respectively; p < 0.05) in the region immediately upstream to the stenosis. These effects were less pronounced for Reynolds number 175. We conclude that stenosis inlet geometry has a significant impact on the flow conditions in the region immediately upstream to the stenosis, which is dependent on the Reynolds number. This may be an important determinant of thrombosis and atherogenesis in this particular region.

Animals↗
PubMed1987

Molecular analysis of the promoter region of the Escherichia coli K-12 phoE gene. Identification of an element, upstream from the promoter, required for efficient expression of phoE protein.

The phoE gene of Escherichia coli codes for an outer membrane pore protein whose expression is induced under phosphate limitation. The promoter of this gene contains a 17 base-pair fragment, designated a pho box, which is present also in other phosphate-controlled promoters. The mRNA start site was determined and found to be located downstream from the pho box, such that this element is located in the -35 region of the phoE promoter. A set of promoter deletions was generated in vitro and analysis of these deletions revealed that sequences upstream from the pho box are required for the efficient expression of phoE. The required upstream region is located (in part) between positions -106 and -121 relative to the mRNA start site, and contains sequences homologous to a pho box and a correctly spaced Pribnow box, but in the reversed orientation relative to the regular -35 and -10 regions. A proper spacing between this upstream region and the -35 region appears to be important, since an oligonucleotide insertion in the intervening region interferes with phoE expression. By cloning the upstream region in a lacZ operon fusion vector, a weak phosphate limitation-inducible promoter activity could be detected.

Bacterial Outer Membrane Proteins↗
PubMed1992

Mutagenesis of the Bacillus subtilis "-12, -24" promoter of the levanase operon and evidence for the existence of an upstream activating sequence.

The levanase operon of Bacillus subtilis is controlled by RNA polymerase associated with sigma 54 factor and by the LevR activator that is homologous to the NifA/NtrC family of regulators. A "-12, -24" promoter is present at the appropriate distance from the transcription start site. The drastic down effect of base substitutions in the TGGCAC, TTGCA consensus sequence on the expression of the levanase operon confirmed the involvement of the "-12, -24" region in promoter function. Deletion derivatives of the upstream sequence of the operon promoter were constructed using translational levD'-'lacZ fusions and were integrated as single copies at the amyE locus of the B. subtilis chromosome. A cis-acting DNA sequence that is required for activation of the operon promoter by LevR was identified. This regulatory sequence is about 50 base-pairs long and is centered 125 base-pairs upstream from the transcription start site in a region containing a 16 base-pair palindromic structure. This region of dyad symmetry functions as a regulatory element when placed up to at least 600 base-pairs upstream from the "-12, -24" promoter, although the efficacy of activation is lowered. Thus, in common with most sigma 54-dependent promoters, an upstream activating sequence (UAS) is involved in the control of expression of the levanase operon. The isolation and characterization of eight mutations in the UAS region confirmed the importance of the palindromic structure in promoter activation. Moreover, the expression of the levanase operon was inhibited by placing the UAS in trans on a multicopy plasmid, probably through titration of the LevR polypeptide. In conclusion, the levanase promoter region can be divided into two regulatory sequences: the "-12, -24" promoter recognized by the sigma 54 RNA polymerase holoenzyme and the UAS, an inverted repeat sequence that is probably the LevR binding site.

Amino Acid Sequence↗