Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Elements”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources
PubMed2003

The cleft lateral lip element: do traditional markings result in secondary deformities?

In cleft surgery, two methods have traditionally been used to mark the height of cupid's bow on the lateral lip element. One technique measures the distance from the oral commissure to the height of cupid's bow on the noncleft side, and transposes this distance onto the cleft-side lateral lip element. The second technique marks the height of cupid's bow on the cleft-side lateral lip element where the white roll disappears. The authors believe these techniques may result in deformities of residual cleft tissue in the repair. Marking the height of cupid's bow on the cleft-side lateral lip element, just before the attenuation of lip fullness, can prevent this deformity. A retrospective study yielded a series of 17 patients with secondary deformities of residual cleft tissue in their repair. The method used to mark the lateral lip element was determined by chart review. Patients then underwent secondary surgery with excision of residual cleft tissue, and repair using the initial technique. A random group of primary cleft patients, repaired using the authors' technique for marking the lateral lip element, was likewise evaluated for the presence of residual cleft tissue in the repair. Of the 17 cases of secondary deformities, 14 were unilateral and 3 were bilateral. Among the unilateral cases, seven were repaired with a triangular flap and seven by rotation advancement. The bilateral cases were repaired using the modified Millard technique. The lateral lip element was marked using cessation of the white roll in 8 patients, and the commissure to the height the of cupid's bow in 2 patients, whereas in 7 patients the method was unreported. Using the authors' technique, both "controls" repaired primarily and cases repaired secondarily resulted in no redundant cleft tissue. Average follow-up was 11 months (range, 1-41 months). The authors think that traditional markings for establishing the height of cupid's bow on the cleft lateral lip element may result in residual cleft tissue in the repair. This deformity can be prevented by marking the height of cupid's bow on the cleft lateral lip element just before the attenuation of lip fullness.

Child, Preschool↗
PubMed1996

Multiprotein transcription factor UAF interacts with the upstream element of the yeast RNA polymerase I promoter and forms a stable preinitiation complex.

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.

Amino Acid Sequence↗
PubMed1990

A developmentally regulated trans-acting factor recognizes dissimilar G/C-rich elements controlling a class of cAMP-inducible Dictyostelium genes.

Transcriptional response elements involved in the cAMP-inducible and developmentally regulated expression of the Dictyostelium aggregate-stage gene pst-cath/CP2 have been shown to include a G/C-rich sequence element [G-box regulatory element (GBRE)]. We have recently identified a trans-acting factor, GBF (GBRE binding factor), that specifically interacts with this sequence and have shown that the binding activity of GBF to GBRE is developmentally regulated and inducible by cAMP. Here, we examine further the possible role of GBF in the regulation of pst-cath/CP2 and three other coordinately regulated, cAMP-inducible aggregate-stage genes. We show that GBF itself (or other closely related factors) recognizes dissimilar G/C-rich elements present in the 5'-flanking regions of these genes and that the ability of the individual, distinct G/C-rich elements to confer regulated expression on a promoter deletion mutant of the pst-cath/CP2 gene is correlated with the relative affinity for GBF. G/C-rich elements carrying point mutations that prevent in vitro binding of GBF to two of the G/C-rich elements fail to activate expression in vivo. An analysis of major points of contact between the GBF protein and two distinctly different binding sites suggests that binding of GBF to these sequence elements involves a considerable degree of flexibility in DNA-protein interactions. These results suggest that the regulated expression of a class of aggregate-stage cAMP-inducible genes involves the interaction of GBF or homologous factors with dissimilar G/C-rich sequence elements and that induction of GBF activity or that of homologous factors by cAMP may thus be a limiting step in the induction of this temporally coordinate set of genes during Dictyostelium development.

Base Sequence↗
PubMed2002

Combinatorial interaction of cis elements specifies the expression of the Arabidopsis AtHsp90-1 gene.

The promoter region of the Arabidopsis AtHsp90-1 gene is congested with heat shock elements and stress response elements, as well as with other potential transcriptional binding sites (activating protein 1, CCAAT/enhancer-binding protein element, and metal regulatory element). To determine how the expression of this bona fide AtHsp90-1 gene is regulated, a comprehensive quantitative and qualitative promoter deletion analysis was conducted under various environmental conditions and during development. The promoter induces gene expression at high levels after heat shock and arsenite treatment. However, our results show that the two stress responses may involve common but not necessarily the same regulatory elements. Whereas for heat induction, heat shock elements and stress response elements act cooperatively to promote high levels of gene expression, arsenite induction seems to require the involvement of activating protein 1 regulatory sequences. In stressed transgenic plants harboring the full-length promoter, beta-glucuronidase activity was prominent in all tissues. Nevertheless, progressive deletion of the promoter decreases the level of expression under heat shock and restricts it predominantly in the two meristems of the plant. In contrast, under arsenite induction, proximal sequences induce AtHsp90-1 gene expression only in the shoot meristem. Distally located elements negatively regulate AtHsp90-1 gene expression under unstressed conditions, whereas flower-specific regulated expression in mature pollen grains suggests the prominent role of the AtHsp90-1 in pollen development. The results show that the regulation of developmental expression, suppression, or stress induction is mainly due to combinatorial contribution of the cis elements in the promoter region of the AtHsp90-1 gene.

Acclimatization↗
PubMed1994

The cis-acting gibberellin response complex in high pI alpha-amylase gene promoters. Requirement of a coupling element for high-level transcription.

In cereal alpha-amylase gene promoters the cis-acting gibberellin response element (GARE) is required for increased transcription in the presence of gibberellin. In low-isoelectric point (pI) alpha-amylase gene promoters a second type of cis element, termed a coupling element, must also be present in a specific position near the GARE; otherwise, the level of transcription in the presence of gibberellin is only a few percent of maximum. The coupling element may help determine where and when in development high-level, hormonally regulated transcription will occur. Such coupling elements have not yet been shown to be necessary for high-level transcription from high-pI alpha-amylase gene promoters. Here we use quantitative transient expression assays to show that a high-pI promoter truncated to -300 is a weak promoter due to the absence of a functional coupling element in the vicinity of the GARE. Gibberellin-induced transcription increases substantially when coupling element function is provided, either by appending upstream regions normally attached to the promoter or by inserting a defined coupling element from a low-pI promoter. Thus, in a second type of gibberellin-regulated promoter coupling element function was found to be crucial for hormone regulation to result in high-level transcription.

Amino Acid Sequence↗
PubMed2003

An approach for reducing adjacent element crosstalk in ultrasound arrays.

A method is presented for active cancellation of crosstalk effects in ultrasonic arrays. The approach makes use of the programmable transmitter waveform generators that are now being used with growing prevalence in diagnostic ultrasound systems. The array's transmit mode transfer function is represented by a transfer function matrix. Elements of this matrix are determined by exciting a single, central element with a wideband waveform and determining the resulting pressure output from the central element and adjacent elements. The desired output then is defined (e.g., finite output from a single, central element) and zero output from all other elements. The transfer function matrix equation can be solved to determine the required excitation functions on both the central array element and its neighbors. These excitation functions will result in reduced evidence of crosstalk on the output signals. Therefore, the single-element, angular-response function is improved. Using superposition, the approach can be extended to beamformed array excitation. A variety of theoretical and experimental results are shown. The method also can be used in the receive mode but with a less satisfactory solution. A transmitting mode experiment based on a prototype five-element transducer has provided results indicating that sidelobes in the angular response can be reduced using this technique.

Journal Article↗
PubMed1993

A third recognition element in bacterial promoters: DNA binding by the alpha subunit of RNA polymerase.

A DNA sequence rich in (A+T), located upstream of the -10, -35 region of the Escherichia coli ribosomal RNA promoter rrnB P1 and called the UP element, stimulates transcription by a factor of 30 in vivo, as well as in vitro in the absence of protein factors other than RNA polymerase (RNAP). When fused to other promoters, such as lacUV5, the UP element also stimulates transcription, indicating that it is a separate promoter module. Mutations in the carboxyl-terminal region of the alpha subunit of RNAP prevent stimulation of these promoters by the UP element although the mutant enzymes are effective in transcribing the "core" promoters (those lacking the UP element). Protection of UP element DNA by the mutant RNAPs is severely reduced in footprinting experiments, suggesting that the selective decrease in transcription might result from defective interactions between alpha and the UP element. Purified alpha binds specifically to the UP element, confirming that alpha acts directly in promoter recognition. Transcription of three other promoters was also reduced by the COOH-terminal alpha mutations. These results suggest that UP elements comprise a third promoter recognition region (in addition to the -10, -35 recognition hexamers, which interact with the sigma subunit) and may account for the presence of (A+T)-rich DNA upstream of many prokaryotic promoters. Since the same alpha mutations also block activation by some transcription factors, mechanisms of promoter stimulation by upstream DNA elements and positive control by certain transcription factors may be related.

Base Sequence↗
PubMed1994

Distribution and evolution of nisin-sucrose elements in Lactococcus lactis.

The distribution, architecture, and conjugal capacity of nisin-sucrose elements in wild-type Lactococcus lactis strains were studied. Element architecture was analyzed with the aid of hybridizations to different probes derived from the nisin-sucrose transposon Tn5276 of L. lactis NIZO R5, including its left and right ends, the nisA gene, and IS1068 (previously designated iso-IS904), located between the left end and the nisA gene. Three classes of nisin-sucrose elements could be distinguished in the 13 strains investigated. Classes I and II consist of conjugative transposons containing a nisA gene and a nisZ gene, respectively. Representative conjugative transposons of these classes include Tn5276 (class I) from L. lactis NIZO R5 and Tn5278 (class II) from L. lactis ILC11. The class II transposon found in L. lactis NCK400 and probably all class II elements are devoid of IS1068-like elements, which eliminates the involvement of an iso-IS1068 element in conjugative transposition. Members of class III contain a nisZ gene, are nonconjugative, and do not contain sequences similar to the left end of Tn5276 at the appropriate position. The class III element from L. lactis NIZO 22186 was found to contain an iso-IS1068 element, termed IS1069, at a position corresponding to that of IS1068 in Tn5276 but in the inverted orientation. The results suggest that an iso-IS1068-mediated rearrangement is responsible for the dislocation of the transposon's left end in this strain. A model for the evolution of nisin-sucrose elements is proposed, and the practical implications for transferring nisin A or nisin Z production and immunity are discussed.

Amino Acid Sequence↗
PubMed1988

Mobilization of Bacteroides plasmids by Bacteroides conjugal elements.

A 4.2-kilobase cryptic Bacteroides plasmid, pB8-51, is found in several colonic Bacteroides species. To determine whether pB8-51 is mobilized by any of the known Bacteroides conjugal elements, we constructed an Escherichia coli-Bacteroides shuttle vector, pVAL-1, which contains pB8-51. We constructed Bacteroides uniformis 0061 derivatives which carry pVAL-1 and various Bacteroides conjugal elements. The Bacteroides conjugal elements tested were six conjugal tetracycline resistance (Tcr) elements (which appear to be chromosomal), i.e., Tcr ERL, Tcr V479, Tcr Emr ERL, Tcr Emr 12256, Tcr Emr DOT, and Tcr Emr CEST, and the conjugal erythromycin resistance (Emr) plasmid pBF4. These Tcr conjugal elements have not been extensively characterized, except for Tcr ERL. All six Tcr elements tested mobilized pVAL-1 at high frequency (10(-3) to 10(-5)) from one Bacteroides strain to another or from a Bacteroides strain to E. coli. Pregrowth of the donors (containing one of the Tcr elements and pVAL-1) in 1 microgram of tetracycline per ml enhanced the transfer of pVAL-1 by 20- to 10,000-fold, depending on which Tcr element was present in the donor. An Ems derivative of pBF4 (pBF4 delta E2) mobilized pVAL-1 from one Bacteroides strain to another at a frequency of 10(-4) but did not mobilize pVAL-1 from a Bacteroides strain to E. coli as efficiently. Thus the Tcr conjugal elements and pBF4 recognize a mobilization region on pB8-51.

Bacteroides↗
PubMed2002

Type 1 capsule genes of Staphylococcus aureus are carried in a staphylococcal cassette chromosome genetic element.

The cap1 genes are required for the synthesis of type 1 capsular polysaccharide (CP1) in Staphylococcus aureus. We previously showed that the cap1 locus was associated with a discrete genetic element in S. aureus M. In this report, we defined the boundaries of the cap1 element by comparing its restriction pattern to that of a corresponding region from the CP1-negative strain Becker. The element was located in the SmaI-G chromosomal fragment of the standard mapping strain NCTC8325. The sequences of the entire cap1 element and the flanking regions were determined. We found that there were two additional cap1 genes not previously identified. The cap1 operon was located in a staphylococcal cassette chromosome (SCC) element similar to the resistance island SCCmec recently described for methicillin resistance in S. aureus. Notably, the SCCcap1 element was located at the same insertion site as all the SCCmec elements in the staphylococcal chromosome. The excision of SCCcap1 could be demonstrated only in the presence of the recombinase genes from an SCCmec element, verifying that SCCcap1 is a genuine SCC element but defective in mobilization. A novel enterotoxin gene, whose transcript was detected by Northern blotting, was found next to the SCCcap1 locus. We propose that the enterotoxin gene and SCCcap1 were inserted into this locus at the juxtaposition by independent events. Sequence comparison revealed numerous DNA rearrangements and mutations in SCCcap1 and the left flanking region, suggesting that the SCCcap1 had been inserted at the SCC attC site a long time ago. In addition, most genes in this region were incomplete, with the exception of the 15 cap1 genes, implying that the cap1 genes confer a survival advantage on strain M.

3' Flanking Region↗
PubMed2006

The clc element of Pseudomonas sp. strain B13, a genomic island with various catabolic properties.

Pseudomonas sp. strain B13 is a bacterium known to degrade chloroaromatic compounds. The properties to use 3- and 4-chlorocatechol are determined by a self-transferable DNA element, the clc element, which normally resides at two locations in the cell's chromosome. Here we report the complete nucleotide sequence of the clc element, demonstrating the unique catabolic properties while showing its relatedness to genomic islands and integrative and conjugative elements rather than to other known catabolic plasmids. As far as catabolic functions, the clc element harbored, in addition to the genes for chlorocatechol degradation, a complete functional operon for 2-aminophenol degradation and genes for a putative aromatic compound transport protein and for a multicomponent aromatic ring dioxygenase similar to anthranilate hydroxylase. The genes for catabolic functions were inducible under various conditions, suggesting a network of catabolic pathway induction. For about half of the open reading frames (ORFs) on the clc element, no clear functional prediction could be given, although some indications were found for functions that were similar to plasmid conjugation. The region in which these ORFs were situated displayed a high overall conservation of nucleotide sequence and gene order to genomic regions in other recently completed bacterial genomes or to other genomic islands. Most notably, except for two discrete regions, the clc element was almost 100% identical over the whole length to a chromosomal region in Burkholderia xenovorans LB400. This indicates the dynamic evolution of this type of element and the continued transition between elements with a more pathogenic character and those with catabolic properties.

Aminophenols↗
PubMed1991

A negative regulatory element in the human papillomavirus type 16 genome acts at the level of late mRNA stability.

A negative regulatory element present in the human papillomavirus type 16 genome has been characterized. Deletion analysis has localized the 5' end of the element to the late region of the genome at the extreme 3' end of the coding region of the L1 open reading frame, around the L1 stop codon, with the element extending into the L1 3' untranslated region. For the cell lines used, the element's function was independent of cell type, tissue, or species of origin, unlike papillomavirus infection, which is very dependent on such factors. By using an mRNA decay assay, we have determined that polyadenylated RNA containing the element is much less stable than polyadenylated RNA lacking the element. This indicates that the element acts as an mRNA instability element. The significance of A-rich, GU-rich, and AUG-rich sequences for the functioning of this human papillomavirus type 16 instability element is discussed.

Base Sequence↗
PubMed2005

Structural and functional analysis of the RNA transport element, a member of an extensive family present in the mouse genome.

We previously identified an RNA transport element (RTE), present in a subclass of rodent intracisternal A particle retroelements (F. Nappi, R. Schneider, A. Zolotukhin, S. Smulevitch, D. Michalowski, J. Bear, B. Felber, and G. Pavlakis, J. Virol. 75:4558-4569, 2001), that is able to replace Rev-responsive element regulation in human immunodeficiency virus type 1. RTE-directed mRNA export is mediated by a still-unknown cellular factor(s), is independent of the CRM1 nuclear export receptor, and is conserved among vertebrates. Here we show that this RTE folds into an extended RNA secondary structure and thus does not resemble any known RTEs. Computer searches revealed the presence of 105 identical elements and more than 3,000 related elements which share at least 70% sequence identity with the RTE and which are found on all mouse chromosomes. These related elements are predicted to fold into RTE-like structures. Comparison of the sequences and structures revealed that the RTE and related elements can be divided into four groups. Mutagenesis of the RTE revealed that the minimal element contains four internal stem-loops, which are indispensable for function in mammalian cells. In contrast, only part of the element is essential to mediate RNA transport in microinjected Xenopus laevis oocyte nuclei. Importantly, the minimal RTE able to promote RNA transport has key structural features which are preserved in all the RTE-related elements, further supporting their functional importance. Therefore, RTE function depends on a complex secondary structure that is important for the interaction with the cellular export factor(s).

Animals↗
PubMed2006

Functional analysis of the tick-borne encephalitis virus cyclization elements indicates major differences between mosquito-borne and tick-borne flaviviruses.

The linear, positive-stranded RNA genome of flaviviruses is thought to adopt a circularized conformation via interactions of short complementary sequence elements located within its terminal regions. This process of RNA cyclization is a crucial precondition for RNA replication. In the case of mosquito-borne flaviviruses, highly conserved cyclization sequences (CS) have been identified, and their functionality has been experimentally confirmed. Here, we provide an experimental identification of CS elements of tick-borne encephalitis virus (TBEV). These elements, termed 5'-CS-A and 3'-CS-A, are conserved among various tick-borne flaviviruses, but they are unrelated to the mosquito-borne CS elements and are located at different genomic positions. The 5'-CS-A element is situated upstream rather than downstream of the AUG start codon and, in contrast to mosquito-borne flaviviruses, it was found that the entire protein C coding region is not essential for TBEV replication. The complementary 3'-CS-A element is located within the bottom stem rather than upstream of the characteristic 3'-terminal stem-loop structure, implying that this part of the proposed structure cannot be formed when the genome is in its circularized conformation. Finally, we demonstrate that the CS-A elements can also mediate their function when the 5'-CS-A element is moved from its natural position to one corresponding to the mosquito-borne CS. The recognition of essential RNA elements and their differences between mosquito-borne and tick-borne flaviviruses has practical implications for the design of replicons in vaccine and vector development.

Animals↗
PubMed1990

Regulatory elements mediating transcription from the Drosophila melanogaster actin 5C proximal promoter.

The major cytoskeletal actin gene of Drosophila melanogaster, the actin 5C gene, has two promoters, the proximal one of which controls constitutive synthesis of actin in all growing tissues. To locate regulatory elements required for constitutive activity of the proximal promoter, mutants of this promoter were fused to the bacterial chloramphenicol acetyltransferase gene and assayed for transient expression activity in cultured Drosophila embryonic Schneider line 2 cells. An essential regulatory element has been located 313 base pairs upstream from the cap site. Deletion of this element lowered expression to one-third of the wild-type level. The element has the sequence AAGTTGTAGTTG, as shown by protein-binding footprinting with the reagent methidiumpropyl-EDTA-Fe(II). This element is probably not a general one, since it was not detected in a search of the published 5'-flanking sequences of 27 Drosophila genes. In addition to this regulatory element, there are five GAGA elements in the actin 5C proximal promoter, some or all of which are essential for the promoter activity as shown by an in vivo competition assay. Although this promoter has no classical TATA element, there is an essential promoter region about 35 base pairs upstream from the cap site that could be a TATA surrogate. The promoter also shows sequences homologous to the alcohol dehydrogenase factor 1-binding site and to the core of the vertebrate serum response element, but mutations of these sites did not affect promoter activity in transient expression assays.

Actins↗
PubMed1990

Negative and positive cis-acting elements control the expression of murine alpha 1-protease inhibitor genes.

The alpha 1-protease inhibitor (alpha 1-PI) proteins of mice are encoded by a group of genes whose members are expressed coordinately in a liver-abundant pattern and are regulated primarily at the transcriptional level. To better understand the developmental and tissue-specific regulation of this gene family, one member that is analogous to the human alpha 1-antitrypsin gene was chosen for study. Deletional analysis of the upstream regulatory region of this gene was performed, spanning from -10 kilobases to -80 base pairs relative to the transcriptional start site. Two functional positive cis-acting elements within the 522 bases immediately upstream of the start site for transcription were shown to modulate the level of expression from this promoter when introduced into human or mouse hepatoma cells, and a third region acted as a negative regulatory element in that its deletion resulted in a two- to sixfold increase of expression of a transfected minigene construct. Sequence comparison between the regulatory domains of two mouse alpha 1-PI genes and the human alpha 1-antitrypsin gene showed that the mouse gene contains a novel positive cis-acting element which is absent in human gene and that a specific eight-base-pair difference between species results in a strong positive cis-acting element in the human gene acting as a negative element in the mouse gene. An enhancer located approximately 3,000 base pairs upstream of the major start site for transcription was also identified. This element is position and orientation independent. Several different DNA-protein binding assays were used to demonstrate that each DNA segment with functional significance in transfection assays interacts specifically with proteins found in adult mouse liver nuclei. The major positive-acting element appeared to be specifically recognized by nuclear proteins found only in tissues that express alpha 1-PI, while the negative element binding proteins were ubiquitous. Thus, the distal regulatory domain including bases -3500 to -133 of this murine alpha 1-PI gene family member is more complex than was previously demonstrated. It is composed of a set of at least three additional functional cis-acting regulatory elements besides those which have been mapped by others and has a far upstream enhancer.

Amino Acid Sequence↗
PubMed1992

Activation of the phosphoenolpyruvate carboxykinase gene retinoic acid response element is dependent on a retinoic acid receptor/coregulator complex.

The accessory factor 1 (AF1) element is an upstream transcriptional control region that plays a role in the response of the phosphoenolpyruvate carboxykinase (PEPCK) gene to both glucocorticoids and retinoic acid. We demonstrate here that retinoic acid receptor alpha (RAR alpha) binds to a sequence within the AF1 element, TGACCT (site B), that is a consensus retinoic acid response element (RARE) half-site. A similar DNA sequence, TGGCCG (site C), located 1 bp downstream of site B, is not involved in the binding of RAR alpha monomers or dimers but is required for the constitution of a functional RARE. Site C is also required for the formation of a complex involving RAR alpha and a liver nuclear factor designated CR, for coregulator. Mutational analysis of the AF1 element shows that the RAR alpha/CR complex is the trans-acting unit that mediates the retinoic acid response of the PEPCK gene. Another member of the retinoid receptor family, retinoid X receptor alpha (RXR alpha), can also form a complex with RAR alpha and the AF1 element. Several observations, including the observation that RXR alpha antibody interacts with CR, indicate that RXR alpha and CR are identical or closely related proteins. Through RXR alpha forms a complex with RAR alpha and the AF1 element, we demonstrate that the AF1 element is functionally distinguishable from a retinoid X response element. Taken together, our results show that the AF1 element contains an RARE that mediates a retinoic acid response by binding an RAR alpha/coregulator complex; this coregulator is presumably RXR alpha.

Base Sequence↗
PubMed1993

Promoter elements determining weak expression of the GAL4 regulatory gene of Saccharomyces cerevisiae.

The GAL4 gene of Saccharomyces cerevisiae (encoding the activator of transcription of the GAL genes) is poorly expressed and is repressed during growth on glucose. To determine the basis for its weak expression and to identify DNA sequences recognized by proteins that activate transcription of a gene that itself encodes an activator of transcription, we have analyzed GAL4 promoter structure. We show that the GAL4 promoter is about 90-fold weaker than the strong GAL1 promoter and at least 7-fold weaker than the feeble URA3 promoter and that this low level of GAL4 expression is primarily due to a weak promoter. By deletion mapping, the GAL4 promoter can be divided into three functional regions. Two of these regions contain positive elements; a distal region termed the UASGAL4 (upstream activation sequence) contains redundant elements that increase promoter function, and a central region termed the UESGAL4 (upstream essential sequence) is essential for even basal levels of GAL4 expression. The third element, an upstream repression sequence, mediates glucose repression of GAL4 expression and is located between the UES and the transcriptional start site. The UASGAL4 is unusual because it is not interchangable with UAS elements in other yeast promoters; it does not function as a UAS element when inserted in a CYC1 promoter, and a normally strong UAS functions poorly in place of UASGAL4 in the GAL4 promoter. Similarly, the UES element of GAL4 does not function as a TATA element in a test promoter, and consensus TATA elements do not function in place of UES elements in the GAL4 promoter. These results suggest that GAL4 contains a weak TATA-less promoter and that the proteins regulating expression of this regulatory gene may be novel and context specific.

Base Sequence↗