Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inverted sequences of the chloramphenicol acetyltransferase (CAT) reporter gene were fused to a soybean tRNA(met(i)) gene lacking a terminator such that the tRNA(met(i)) sequences caused the co-transcription of CAT antisense sequences by RNA polymerase III. When electroporated into carrot protoplasts, these antisense DNA constructs suppressed CAT enzyme activity expressed from co-electroporated DNAs containing the CAT gene downstream of the cauliflower mosaic virus (CaMV) 35S RNA promoter. Our most effective construct, an antisense sequence complementary to the 3' portion of the CAT gene, inhibited CAT activity five-fold greater than an antisense construct expressed by RNA polymerase II from the cauliflower mosaic virus 35S RNA promoter. These results indicate that antisense sequences transcribed by RNA polymerase III should efficiently suppress gene expression in plants.
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PMID:Suppression of gene expression in plant cells utilizing antisense sequences transcribed by RNA polymerase III. 162 77

Site-directed mutagenesis was used to examine the organization of cis-acting regulatory elements that comprise the promoter of the early 35,000-molecular-weight protein gene (35K protein gene) encoded by the EcoRI-S region of the baculovirus Autographa californica nuclear polyhedrosis virus. The promoter fragment, extending from positions -226 to +12 relative to the early RNA start site (position +1), was fused to the reporter gene encoding chloramphenicol acetyltransferase (CAT) and then inserted into the genome of recombinant viruses (3.96 map units) in order to ascertain the role of regulatory elements in the context of a normal infection. A combination of deletions and linker insertions revealed that early transcription was mediated by a basal (minimum) promoter, consisting of the TATA element (positions -30 to -25), that was in turn responsive to an upstream activating region located between -90 and -30. The TATA element exerted the single greatest influence on the level of early promoter activity and contained all information necessary to direct transcription from a site located 30 nucleotides downstream. The upstream activating region provided a 10- to 15-fold stimulation of transcription from the early +1 start site that was mediated by distinct DNA elements. These regulatory elements included two GC motifs (centered at positions -81 and -54, respectively), composed of alternating G and C residues, and a CGT motif (position -40) that contained the core sequence A(A/T)CGT(G/T). Each motif was required for full promoter activity during the early phase of infection. This organization that employs diverse cis-acting stimulatory elements is typical of promoters responsive to RNA polymerase II and may facilitate increased expression of A. californica nuclear polyhedrosis virus genes early in infection when the level of viral DNA for transcription is critically low.
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PMID:Identification of upstream promoter elements mediating early transcription from the 35,000-molecular-weight protein gene of Autographa californica nuclear polyhedrosis virus. 207 43

We found that the 5' nontranslated leader sequence from encephalomyocarditis virus (EMCV) allowed transcripts that were synthesized by the T3 RNA polymerase in mammalian cells to be translated in a cap-independent fashion. Stable mouse cell lines that carry the T3 RNA polymerase gene expressed the chloramphenicol acetyltransferase (CAT) gene under the control of a phage promoter when the CAT gene was fused to the EMCV leader and introduced into the cells by transient DNA uptake. The level of gene expression in such cells was similar to or greater than that observed with a conventional transient expression vector that is dependent on transcription by the host RNA polymerase II. Expression of the EMCV-CAT fusion gene was stimulated by cotransfection of the cells with a gene that encodes the poliovirus protease 2A protein (which inhibits cap-dependent translation), demonstrating that the EMCV-CAT fusion gene was expressed in a cap-independent fashion. Introduction of both the T3 RNA polymerase gene and the EMCV-CAT fusion gene into a variety of cultured mammalian cell lines (HeLa, BSC40, Ltk-, NIH 3T3, and C127) demonstrated that the T3-EMCV expression system functions in a broad range of cell types.
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PMID:Synthesis of functional mRNA in mammalian cells by bacteriophage T3 RNA polymerase. 216 33

By using chloramphenicol acetyltransferase (CAT) assays in neuron-derived cell lines, we show here that promoter activity associated with the herpes simplex virus type 1 latency-associated transcript (LAT) had neuronal specificity. Promoter activity in these transient CAT assays coincided with a DNA region containing excellent RNA polymerase II promoter consensus sequences. Primer extension analysis in a LAT promoter-CAT plasmid construct placed the start of transcription about 28 nucleotides from the first T in the consensus TATA box sequence. Neuronal specificity of this promoter was suggested by examining the effect of sequences upstream of the promoter on CAT activity in neuronal versus nonneuronal cells. In nonneuronal cells, promoter activity was decreased 3- to 12-fold with the addition of upstream sequences. In contrast, in neuron-derived cells, the addition of upstream sequences did not decrease promoter activity. The LAT promoter predicted by our transient CAT assays was located over 660 nucleotides upstream from the 5' end of the previously mapped 2-kilobase (kb) LAT. This unusual location was explained by in situ and Northern (RNA) blot hybridization analyses that suggested that LAT transcription began near the promoter detected in our CAT assays, rather than near the 5' end of the 2-kb LAT. In situ hybridization with neurons from latently infected rabbits detected small amounts of LAT RNA within 30 nucleotides of the consensus TATA box sequence. This suggested that LAT transcription began near this TATA box. Northern blot hybridization of RNA from ganglia of latently infected rabbits revealed a faint 8.3-kb band of the same sense as LAT. We conclude that (i) the LAT promoter has neuronal specificity, (ii) the LAT promoter is located over 660 nucleotides upstream of the 5' end of the previously characterized stable 2-kb LAT, (iii) LAT transcription begins about 28 nucleotides from the first T of the consensus TATA box sequence and extends to near the first available polyadenylation site approximately 8.3 kb away, and (iv) this 8.3-kb RNA may be an unstable precursor of the more stable 2- and 1.3-kb LATs.
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PMID:Activity of herpes simplex virus type 1 latency-associated transcript (LAT) promoter in neuron-derived cells: evidence for neuron specificity and for a large LAT transcript. 216 84

The herpes simplex virus latency-associated transcript (LAT) gene is the only viral gene that shows substantial transcriptional activity during neuronal latency. The LAT RNA produced is antisense to the mRNA of the immediate early gene ICP0, partially overlaps the ICP0 mRNA, and is suspected of playing some role in latency. Sequence analysis of the region 5' to the reported transcription start site has not revealed any high consensus RNA polymerase II promoter elements. Nonetheless, LAT RNA is transcribed in low abundance during acute infection in tissue culture. As the initial step in mapping the promoter for this latency-associated gene, we analysed the ability of different regions of the LAT gene to drive the transcription of an indicator gene in vitro. Using chloramphenicol acetyltransferase (CAT) assays, we found that the genomic region between -940 and -662 nucleotides upstream of the transcription start site of the LAT gene was most efficient at directing transcription of the indicator CAT gene in Vero cells. This suggests that the LAT promoter, or at least the promoter controlling transcription of this gene during acute infection in tissue culture, may have an unusual location of more than 662 nucleotides upstream from the reported start of RNA transcription.
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PMID:In vitro promoter activity associated with the latency-associated transcript gene of herpes simplex virus type 1. 254 85

In order to understand the process of transcription termination by eukaryotic RNA polymerase II, the transcription termination region of the advenovirus 2 major late transcription unit was analysed in a transient transfection system. Previously, it had been demonstrated that the entire sequence from map units (m.u.) 97.1 to 100 of the adenovirus 2 genome terminates transcription when inserted into the 5' or 3' untranslated sequences of the chloramphenicol acetyltransferase gene. Using subclones and Bal 31 deletion mutants of the termination region, we have shown that the termination region consists of multiple elements each capable of inhibiting gene expression independently. A DNA sequence analysis reveals the presence of a highly repetitive A-rich sequence motif throughout the entire termination region. The data suggest that the A-rich motif may mediate the transcription termination process.
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PMID:The transcription termination region of the adenovirus 2 major late transcript contains multiple functional elements. 265 32

We examined the structural and functional properties of a human H3 histone gene promoter. The complete nucleotide sequence of an H3 structural gene and 515 nucleotides of 5' and 100 nucleotides of 3' flanking sequences were determined. The upstream region of this cell cycle dependent H3 histone gene, designated pST519, contains consensus sequences typical of genes transcribed by RNA polymerase II. To address promoter function directly, we determined the capability of the 5' flanking sequences to direct the transcription of two genes which are not functionally or structurally related. Fusion genes were constructed using the 5' flanking sequences of this human H3 histone gene and either human beta-globin or bacterial chloramphenicol acetyltransferase (CAT) coding sequences. Both of these fusion genes were expressed when transfected into HeLa cells. Under control of the pST519 histone gene promoter, a beta-globin mRNA transcript was initiated at the appropriate H3 (bp) enhancer, inserted upstream from the histone promoter in both fusion constructs, increased levels of beta-globin and CAT expression. Expression of the pST519 H3 histone gene in COS cells in the absence of the SV40 72-bp enhancer confirmed that the sequences required for promoting transcription reside within the 750-bp 5' flanking sequences and that the exogenous enhancer facilitates, but is not a prerequisite for, transcription. Enhancer-facilitated expression of a cell cycle dependent human H4 histone gene was also observed following transfection into mouse L cells and indicates that the regulatory sequences of human histone genes and transcription factors of mouse cells are compatible.
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PMID:Enhancer-facilitated expression of prokaryotic and eukaryotic genes using human histone gene 5' regulatory sequences. 301 46

We have analyzed the effect of insertion mutants between the simian virus 40 (SV40) 21-base pair (bp) repeats and the early-early (EE) TATA sequence. Insertion of 4, 42, or 90 bp of DNA at the SV40 NcoI site (map position 37) has been analyzed for its effect on expression of the SV40 early gene and positioning of the RNA 5' ends. Insertion of 4 bp reduced SV40 early promoter-dependent chloramphenicol acetyltransferase (CAT) expression by six- to eightfold. Increasing the size of the insertion to 42 or 90 bp resulted in a further drop in early gene expression to basal levels. At the RNA level, the 4-bp insertion reduced EE RNA synthesis approximately 10-fold. No concomitant increase in late-early (LE) RNA synthesis was observed. Insertion of 42 or 90 bp of DNA resulted in a decrease of EE RNA synthesis and a stimulation of LE RNA synthesis. Deletion of the SV40 72-bp repeats from the insertion mutants demonstrated that some, but not all, of the LE RNA depends upon the presence of these sequences. These studies suggest that the ability of RNA polymerase II to utilize the EE (TATA-directed) transcriptional control sequence requires an interaction with the upstream 21-bp repeats or the 72-bp repeats or both. That LE RNA levels in pJI1-in42 CAT and pJI1-in90 CAT were equivalent to the level of EE RNA in pJI1-CAT, yet the level of CAT gene expression was decreased greater than 10-fold, suggests that LE mRNA is under translational control and probably prefers a 5' initiation codon proximal to that of the CAT gene.
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PMID:Spacing between simian virus 40 early transcriptional control sequences is important for regulation of early RNA synthesis and gene expression. 302 82

DNA polymerase beta (beta-pol) is a housekeeping enzyme considered to be involved in DNA repair in vertebrate cells. We cloned a fragment of genomic DNA spanning the first two exons of the human beta-pol gene and approximately 11 kilobases of the flanking region. The segment just 5' of the transcription start site can direct expression of the bacterial chloramphenicol acetyltransferase (CAT) gene in HeLa cells. A sequence containing only 113 base pairs of flanking DNA has promoter activity, and various constructs containing up to 4.8 kilobases of flanking sequence are expressed at a similar level, indicating that with this assay the important regulatory elements are located within or proximal to the approximately 100-bp core promoter. S1 nuclease mapping was used to show that transcription of the transfected genes is initiated at the same position as the endogenous beta-pol gene. The region upstream of the transcription start site is G + C rich and contains neither CAAT nor TATA boxes, but does have three decanucleotide elements matching high affinity binding sites for the RNA polymerase II transcription factor Sp1. Extending 5' from position -39 and surrounded by Sp1 consensus binding elements, there is a 10-nucleotide sequence with perfect dyad symmetry, GTGACGTCAC. Similar sequences are found in a number of cellular and viral promoters, including several adenovirus promoters. Experiments to test whether the core beta-pol promoter is activated by the adenovirus early region products showed that cotransfection with an adenovirus expression plasmid strongly activates expression of the beta-pol promoter.
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PMID:Human beta-polymerase gene. Structure of the 5'-flanking region and active promoter. 318 28

We characterized the transcription termination region of the chicken beta H-globin gene. First we located the region by nuclear runon transcription in vitro. Then we sequenced and subcloned it into a chloramphenicol acetyltransferase (CAT) expression vector for assay in vivo. The region of beta H termination contains two interesting elements located about 1 kilobase downstream of the beta H gene poly(A) site. Either element alone can block CAT expression if inserted between the promoter and the poly(A) site of the cat gene in pRSVcat. The first element in the termination region is an unusually large inverted repeat in the DNA (delta G = -71 kcal). The second element, 200 base pairs further downstream, is an RNA polymerase II promoter which directs transcription back upstream on the complementary strand. This transcription converges on and collides with that from the beta H gene at or near the inverted repeat where transcription from both directions stops. We propose that the inverted repeat is a strong pause site which positions the converging polymerases for mutual site-specific termination.
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PMID:Transcription termination at the chicken beta H-globin gene. 324 59


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