Rapid purification of covalently closed circular DNAs of bacterial plasmids and animal tumor viruses

Induction of phenylalanine ammonia-lyase and 4-coumarate:CoA ligase mRNAs in cultured plant cells by UV light or fungal elicitor

The mRNAs encoding two enzymes of phenylpropanoid metabolism, phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) and 4-coumarate:CoA ligase (4CL; EC 6.2.1.12), were induced in cultured parsley cells (Petroselinum hortense) either by irradiation with UV light or by treatment with elicitor, a cell-wall fraction of the fungus Phytophthora megasperma f. sp. glycinea. Two-dimensional gel electrophoresis of the encoded PAL and 4CL proteins revealed that the mRNAs induced by either treatment were very similar if not identical. RNA blot hybridization with cDNAs complementary to these mRNAs was used to measure changes in the mRNA amounts at various times after either treatment. Total cellular PAL and 4CL mRNA amounts increased coordinately after UV irradiation to a maximum at 7 hr and then decreased to uninduced levels by 30 hr with the same kinetics as observed previously for the changes in the translational activities. Treatment with the fungal elicitor also caused coordinated, but more rapid, changes in PAL and 4CL mRNA translational activities, with a sharp peak occurring 3 hr after the addition of elicitor. Corresponding changes in mRNA amounts were observed only for 4CL, whereas the amount of PAL mRNA continued to increase at least up to 20 hr after elicitor addition. Our results suggest that parsley cells respond to UV irradiation or addition of fungal elicitor by increased rates of transcription of genes involved in the synthesis of compounds related to UV or disease resistance, respectively.

Rapid activation by fungal elicitor of genes encoding "pathogenesis-related" proteins in cultured parsley cells

Administration of a cell-wall preparation from the fungus Phytophthora megasperma f. sp. glycinea, which acts as an elicitor of phytoalexin production in cell suspension cultures of parsley (Petroselinum crispum), also results in a rapid and dramatic increase in the relative amounts of mRNAs coding for a number of small proteins having low isoelectric points. According to various operational criteria, the translation products are classified as "pathogenesis-related" (PR) proteins. Here we report that the cDNA inserts of two pBR322-derived plasmids, pcPR1 and pcPR2, are homologous to mRNAs coding for one (PR1) and three (PR2) of these proteins in hybrid-selected in vitro translation experiments. Nuclear run-off transcription studies show that activation of the corresponding genes is extremely rapid; we observed a 4-fold increase in the transcription rate of the PR1 gene within 5 min and a 3-fold increase for the PR2 gene within 20 min following elicitation. Subsequent increases in the amounts of PR1 and PR2 mRNAs indicate that regulation of PR protein synthesis occurs at the transcriptional level.

Human papillomavirus DNA from warts for typing by endonuclease restriction patterns: purification by alkaline plasmid methods

The alkaline plasmid DNA extraction method of Birnboim and Doly was applied for the isolation of human papillomavirus (HPV) from warts. Tissue from common and plantar warts was digested with proteinase K, and the extrachromosomal circular covalently-closed form of HPV-DNA was rapidly extracted by alkaline sodium dodecyl sulphate and phenol-chloroform treatment. Recovery of HPV-DNA from the tissue was sufficient for determination of endonuclease restriction patterns by agarose gel electrophoresis.

Structure of mouse 2',3'-cyclic-nucleotide 3'-phosphodiesterase gene

The mouse 2',3'-cyclic-nucleotide 3'-phosphodiesterase gene was isolated from a mouse gene library. Restriction endonuclease mapping and DNA sequencing analysis revealed that this gene is about 6 kb long and is separated into three exons by two introns. The transcription initiation site was identified. The mouse cDNA of 2374 bp was obtained and used for the screening and analysis of the gene.

Virulence studies based on plasmid profiles of the fish pathogen Vibrio salmonicida

Strains of Vibrio salmonicida isolated from Atlantic salmon (Salmo salar) and rainbow trout (Salmo gairdneri) suffering from cold-water vibriosis could be divided on the basis of plasmid profiles into four different categories. Of 32 strains, 19% harbored three plasmids of 24, 3.4, and 26 megadaltons (MDa), 69% harbored the 24- and 3.4-MDa plasmids but not the 2.6-MDA plasmid, and 9% harbored only the 24-MDA plasmid. The fourth category, which consisted of only one strain, harbored a plasmid of 10 MDa. In spite of different plasmid patterns, the strains of V. salmonicida were very similar with respect to biochemical reactions. The one-third of the V. salmonicida strains which were serotyped were of the same type. The 50% lethal doses, which were determined by intraperitoneal injection, ranged from 4 x 106 to 1 x 108 CFU per fish.

cDNA cloning and amino acid sequence of human brain 2',3'-cyclic-nucleotide 3'-phosphodiesterase

A cDNA of 1762 base pairs was obtained from a cDNA library of human brain by immunoscreening, and the nucleotide sequence of the cDNA was determined. The complete amino acid sequence of human 2',3'-cyclic-nucleotide 3'-phosphodiesterase was deduced from the nucleotide sequence of the cDNA. Human enzyme was found to contain 401 amino acids including initiation methionine and have a molecular weight of 45,098. RNA blot hybridization revealed a single mRNA band at the position of about 3000 bases. DNA blot hybridization suggested that a single-copy 2',3'-cyclic-nucleotide 3'-phosphodiesterase gene exists per haploid genome.

Increment of DNA topoisomerases in chemically and virally transformed cells

The activities of topoisomerases I and II were assayed in subcellular extracts obtained from nontumorigenic BALB/c 3T3 A31 and normal rat kidney (NRK) cell lines and from the same cells transformed by benzo[a]pyrene (BP-A31), Moloney (M-MSV-A31) and Kirsten (K-A31) sarcoma viruses, and simian virus 40 (SV-NRK). The enzymatic activity of topoisomerase I was monitored by the relaxation of negatively supercoiled pBR322 DNA and by the formation of covalent complexes between 32P-labeled DNA and topoisomerase I. Topoisomerase II activity was determined by decatenation of kinetoplast DNA (k-DNA). It was found that nuclear and cytoplasmic type I topoisomerase specific activities were higher in every transformed cell line than in the normal counterparts. These differences cannot be attributed to an inhibitory factor present in A31 cells. When chromatin was treated at increasing ionic strengths, the 0.4 M NaCl extract showed the highest topoisomerase I specific activity. Moreover, in this fraction the transformed cells exhibited the most significant increment in the enzymatic activity as compared with nontransformed cultures. Spontaneously transformed A31 cells showed topoisomerase I activity similar to that of extracts of cells transformed by benzo[a]pyrene. Topoisomerase II specific activity was also increased in SV-NRK cells, as judged by the assay for decatenation of k-DNA to yield minicircle DNA.

Effects of human transforming growth factors on topoisomerases from normal fibroblasts

Normal rat kidney fibroblasts (NRK-B F49) treated at transforming doses with a gamma-like TGF, partially purified from human melanoma, showed a 3 to 5 fold increase in DNA type II topoisomerase activity. A similar effect was observed using EGF and a partially purified alfa TGF from rabbit fetuses. DNA type I topoisomerase activity, from the same cells, was not significantly modified by treatment with these growth factors. Topoisomerase II stimulation was dependent on mRNA synthesis. The possible role of topoisomerase II in phenotypical cell transformation induced by TGF is discussed.

Mitoxantrone affects topoisomerase activities in human breast cancer cells

The effects of mitoxantrone, an antineoplastic DNA intercalator, on topoisomerase I and II were studied in two human breast cancer cell lines. A large increase of topoisomerase I activity was found when cells were exposed to various doses of mitoxantrone. Maximal effect was achieved with 20 and 40 ng/mL in T47D and MCF-7 cells respectively. The enhancement on topoisomerase I activity seemed to be reversible, to be dependent on time of exposure to the drug and to require cellular integrity. Type II topoisomerase was inhibited in T47D cells after treatment for one hour with 10 ng/mL of mitoxantrone and enzyme activity was undetectable at higher doses (40 ng/mL). This inhibitory effect did not take place in vitro unless the concentration of the intercalator was increased to 400-500 ng/mL.

An economical large scale procedure to purify E. coli amplifiable plasmids for DNA sequencing, in vitro transcription and in vitro mutagenesis

A reproducible and economical procedure for obtaining a large and quantitative yield of highly purified covalently closed circular plasmid DNA is described. The procedure departs in several ways from more commonly used methods. These are a) avoidance of the use of CsCl, ethidium bromide and ultracentrifuge, b) enrichment of the plasmid DNA by selective denaturation of chromosomal DNA with an alkaline-SDS solution, c) enrichment of covalently closed circular plasmid DNA by extraction with acid-phenol, and d) removal of small degraded RNA fragments by molecular sieve chromatography after digestion with RNase A. The plasmid DNA prepared by this new procedure is free of contaminants and has been used for DNA sequencing, in vitro transcription, transformation and in vitro mutagenesis.

In vitro transcription initiation from three different Escherichia coli promoters. Effect of supercoiling

Transcription initiation from beta-lactamase, tetracycline resistance and RNA 1 promoters, present in plasmid pAT153, were studied employing the abortive initiation technique. Assays appear to be promoter-specific with supercoiled and linear templates. Supercoiling enhances the isomerization rate constant of the open RNA-polymerase--promoter complex formation. Results agree with the in vivo behaviour of the corresponding promoters, and allow us to propose a hypothesis about the effect of supercoiling on transcription initiation.

Post-transcriptional regulation of glyceraldehyde-3-phosphate-dehydrogenase gene expression in rat tissues

We have isolated and identified cDNA clones containing part of the coding sequence for rat glyceraldehyde-3-phosphate-dehydrogenase (GAPDH, E.C. 1.2.1.12). By using one of these clones as a probe, we have shown that: i) the abundance of GAPDH mRNA is different in various tissues of the adult rat and in good correlation with the abundance of the enzyme; ii) the transcription rates are quite similar in all tissues tested. We therefore conclude that the tissue-specific differential GAPDH gene expression is regulated by adjusting the abundance of its mRNA at the post-transcriptional level.

Isolation and partial characterization of plasmid DNA from Arthrobacter oxidans

A method for the extraction of the high molecular weight plasmid AO 1 from the gram-positive soil bacterium Arthrobacter oxidans is presented. Following digestion of this DNA with the restriction endonucleases AccI, Bam HI, Eco RI and Hind III, an average molecular mass of 157.8 kb was estimated. This value is in good agreement with the 160 kb size determined previously by electron microscopy (Brandsch et al. 1982). Using the same method, no plasmid DNA was found in strains of the genus Arthrobacter which do not degrade nicotine, e.g., A. albidus, A. globiformis and A. auricans.

Microscale method for rapid isolation of covalently closed circular plasmid DNA from group N streptococci

A method for rapid purification of plasmid DNA from lactic streptococci, utilizing microliter quantities of reagents, was developed by combination of a short lysozyme-mutanolysin cell wall digestion with a modification of the Escherichia coli plasmid isolation procedure of McMaster et al. (Anal. Biochem. 109:47-54, 1980). The preparations obtained were highly enriched for covalently closed circular DNA, and the method was applicable to plasmids of at least 40 megadaltons. Centrifugation in CsCl-ethidium bromide density gradients was not required.

A note on the presence of novel DNA species in the spoilage yeasts Zygosaccharomyces bailii and Pichia membranaefaciens

Two novel covalently closed circular DNA species of 5.4 and 6.0 kilobases were detected in strains of Zygosaccharomyces bailii with a rapid small scale isolation procedure. The 5.4 kb species was found in four strains and both species were found in three strains. A novel, covalently-closed circular DNA species of 6.9 kb was detected in four of 12 strains of Pichia membranaefaciens . Plasmid DNA (2 micron) (that is CCC DNA of approximately 6 kb in Saccharomyces cerevisiae) was detected in 38 of 40 strains of Sacch . cerevisiae confirming reports of the widespread distribution of this plasmid.

Complete nucleotide sequence of the messenger RNA coding for chicken muscle glyceraldehyde-3-phosphate dehydrogenase

The complete nucleotide sequence for chicken glyceraldehyde-3-phosphate dehydrogenase mRNA has been determined, thereby extending the longest such sequence previously reported (Dugaiczyk et al. Biochemistry, 1983, 22, 1605-1613) by 27 nucleotides. The complete mRNA with the exclusion of poly(A) is 1284 nucleotides long and contains 56 nucleotides of 5' non coding sequence and 229 nucleotides of 3' non coding region. Knowledge of the complete sequence allows us to propose secondary structures models which may be of biological significance.

Cloning and expression of a p-aminobenzoic acid synthetase gene of the candicidin-producing Streptomyces griseus

4.5-kb BamHI fragments of DNA coding for p-aminobenzoic acid (PABA) synthetase from the candicidin-producing Streptomyces griseus IMRU 3570 and from a sulphonamide resistant mutant of it were cloned on the plasmid vector pIJ41 into Streptomyces lividans 66. The cloned DNA restored prototrophy to a pab auxotroph of S. lividans; when the S. griseus donor was a sulphonamide resistant, PABA-overproducing mutant, the S. lividans clone was sulphonamide resistant as well as Pab+. Sub-cloning the 4.5-kb fragment of S. griseus DNA into Escherichia coli pabA- or pabB- mutants by insertion at the BamHI site of pBR322 did not yield prototrophic clones directly. However, when the cloned fragment had the proper orientation relative to the tet promoter, but not the opposite one, it was possible to select Pab+ colonies, which arose by deletion in vivo of approx. 1 kb of the S. griseus inserted DNA. These results, and those of studies in which Tn5 abolished the Pab+ phenotype by insertion in vivo in the tet promoter or downstream of it, indicated that the S. griseus pab promoter was not expressed in E. coli but that the pab gene could be expressed by transcriptional readthrough from the vector. Experiments in which the cloned DNA was transferred back from E. coli to S. lividans suggested, but did not prove, that the Streptomyces pab promoter had been deleted by loss of the approx. 1-kb segment. These experiments showed expression of both the tet (of pBR322) and kan (of Tn5) promoters in S. lividans.

Analysis of simian virus 40 chromosome-T-antigen complexes: T-antigen is preferentially associated with early replicating DNA intermediates

The fraction and DNA composition of simian virus 40 chromosomes that were complexed with large T-antigens (T-Ag) were determined at the peak of viral DNA replication. Simian virus 40 chromatin containing radiolabeled DNA was extracted by the hypotonic method of Su and DePamphilis (Proc. Natl. Acad. Sci. U.S.A. 73:3466-3470, 1976) and then fractionated by sucrose gradient sedimentation into replicating (90S) and mature (70S) chromosomes. Viral chromosomes containing T-Ag were isolated by immunoprecipitation with saturating amounts of either an anti-T-Ag monoclonal antibody or an anti-T-Ag hamster serum under conditions that specifically precipitated T-Ag protein from cytosol extracts. An average of 10% of the uniformly labeled DNA in the 90S pool and 7.5% in the 70S pool was specifically precipitated, demonstrating that under these conditions immunologically reactive T-Ag was tightly bound to only 8% of the total viral chromosomes. In contrast, simian virus 40 replicating intermediates (RI) represented only 1.2% of the viral DNA, but most of these molecules were associated with T-Ag. At the shortest pulse-labeling periods, an average of 72 +/- 18% of the radiolabeled DNA in 90S chromosomes could be immunoprecipitated, and this value rapidly decreased as the labeling period was increased. Electron microscopic analysis of the DNA before and after precipitation revealed that about 55% of the 90S chromosomal RI and 72% of the total RI from both pools were specifically bound to T-Ag. Comparison of the extent of replication with the fraction of RI precipitated revealed a strong selection for early replicating DNA intermediates. Essentially all of the RI in the 70S chromosomes were less than 30% replicated and were precipitated with anti-T-Ag monoclonal antibody or hamster antiserum. An average of 88% of the 90S chromosomal RI which were from 5 to 75% replicated were immunoprecipitated, but the proportion of RI associated with T-Ag rapidly decreased as replication proceeded beyond 70% completion. By the time sibling chromosomes had separated, only 3% of the newly replicated catenated dimers in the 90S pool (<1% of the dimers in both pools) were associated with T-Ag. Measurements of the fraction of radiolabeled DNA in each quarter of the genome confirmed that T-Ag was preferentially associated with newly initiated molecules in which the nascent DNA was nearest the origin of replication. These results are consistent with a specific requirement for the binding of T-Ag to viral chromosomes to initiate DNA replication, and they also demonstrate that T-Ag does not immediately dissociate from chromosomes once replication begins. The biphasic relationship between the fraction of T-Ag-containing RI and the extent of DNA replication suggests either that 1 or 2 molecules of T-Ag remain stably bound until replication is about 70% completed or that 4 to 6 molecules of T-Ag are randomly released from each RI at a uniform rate throughout replication.

cDNA cloning and analysis of chick-embryo-liver cytochrome P-450 mRNA induced by porphyrinogenic drugs

Hepatic microsomal cytochrome P-450 was elevated in 17-day chick embryos by combined administration of the porphyrinogenic drugs 2-allyl-2-isopropylacetamide and 3,5-diethoxycarbonyl-1,4-dihydrocollidine. Increased apoprotein levels were the result of de novo protein synthesis; in vitro obtained translation data suggested that cytochrome P-450 mRNA levels were elevated. A 1000-base cDNA sequence for the drug-induced cytochrome P-450 mRNA was isolated from a chick embryo cDNA 'library' and this was used as a specific probe to investigate drug-mediated induction of cytochrome P-450 mRNA. RNA-DNA 'dot' hybridisation studies demonstrated that drug treatment led to a 3-5-fold increase in the level of this mRNA and that the mRNA was predominantly associated with membrane-bound polyribosomes. Treatment of embryos with the drugs individually demonstrated that both of them induced synthesis of the same mRNA. These studies show directly that treatment of chick embryos with 2-allyl-2-isopropylacetamide or 3,5-diethoxycarbonyl-1,4-dihydrocollidine caused increased levels of cytochrome P-450 mRNA and suggest that this involved increased transcription of the gene.

Transcription of adenovirus 5 early region 1b is elevated in permissive cells infected by a mutant with an upstream deletion

Early region 1b (E1b) of adenovirus 5 consists of a single transcription unit that lies from 1,702 to 4,070 nucleotides from the conventional left end of the genome. The effect of mutations that map upstream of E1b on the production of E1b mRNA was examined in vivo with mutants defective in gene functions from the neighboring early region 1a (E1a) transcription unit (499 to 1,632 nucleotides from the left end). These host range mutants replicate in the adenovirus 5-transformed human cell line 293. E1b mRNA accumulation was assayed by DNA-RNA hybridization late after productive infection when the E1b transcripts are abundant in the cytoplasm. Cells infected by wild-type virus, mutant dl311, or mutant hr1. The elevated levels of E1b mRNA were also detected in steady-state nuclear RNA, pulse-labeled polyadenylated nuclear RNA, and pulse-labeled total nuclear RNA. These data indicate that E1b transcription was elevated in human 293 cells infected with dl312. There was no evidence of increases in genomic DNA in dl312-infected cells, suggesting that the rate of transcription may be elevated. When mixed infections with a 10-fold excess of either dl312 or wild-type virus were performed, the phenotype was that of the more abundant genome. This result suggests that the respective phenotypes were cis dominant. The increased rate of transcription can be attributed to cis-active regulatory effects of the deletion of nucleotides 448 to 1,349 in mutant dl312 DNA.

pIJ101, a multi-copy broad host-range Streptomyces plasmid: functional analysis and development of DNA cloning vectors

Streptomyces lividans ISP 5434 contains four small high copy number plasmids: pIJ101 (8.9 kb), pIJ102 (4.0 kb), pIJ103 (3.9 kb) and pIJ104 (4.9 kb). The three smaller species appear to be naturally occurring deletion variants of pIJ101. pIJ101 and its in vivo and in vitro derivatives were studied after transformation into S. lividans 66. pIJ101 was found to be self-transmissible by conjugation, to elicit "lethal zygosis" and to promote chromosomal recombination at high frequency in both S. lividans 66 and S. coelicolor A3(2). A restriction endonuclease cleavage map of pIJ101 was constructed for 11 endonucleases; sites for five others were lacking. Many variants of pIJ101 were constructed in vitro by inserting DNA fragments determining resistance to neomycin, thiostrepton or viomycin, and having BamHI termini, into MboI or BclI sites on the plasmid, sometimes with deletion of segments of plasmid DNA. The physical maps of these plasmids were related to their phenotypes in respect of lethal zygosis and transfer properties. In vivo recombination tests between pairs of variant plasmids were also done. These physical and genetic studies indicated that determinants of conjugal transfer occupy less than 2.1 kb of the plasmid. A second segment is required for spread of the plasmid within a plasmid-free culture to produce the normal lethal zygosis phenotype: insertion of foreign DNA in this region caused a marked reduction in the diameter of lethal zygosis zones. The minimum replicon was deduced to be 2.1 kb or less in size; adjacent to this region is a 0.5 kb segment which may be required for stable inheritance of the plasmid. The copy number of several derivatives of pIJ101 in S. lividans 66 was between 40 and 300 per chromosome and appeared to vary with the age or physiological state of the culture. pIJ101 derivatives have a wide host range within the genus Streptomyces: 13 out of 18 strains, of diverse species, were successfully transformed. Knowledge of dispensable DNA segments and the availability of restriction sites for the insertion of DNA, deduced from the properties of plasmids carrying the E. coli plasmid pACYC184 introduced at various sites, was used in the construction of several derivatives of pIJ101 suitable as DNA cloning vectors. These were mostly designed to be non-conjugative and to carry pairs of resistance genes for selection. They include a bifunctional shuttle vector for E. coli and Streptomyces; a Streptomyces viomycin resistance gene of this plasmid is expressed in both hosts.

Organization of human histone genes

We describe the isolation and initial characterization of seven independent lambda Charon 4A recombinant phages which contain human histone genomic sequences (designated lambda HHG). Restriction maps of these clones and localization of the genes coding for histones H2A, H2B, H3, and H4 are presented. The presence of histone encoding regions in the lambda HHG clones was demonstrated by several independent criteria including hybridization with specific DNA probes, hybrid selection/in vitro translation, and hybridization of lambda HHG DNAs to reserve Southern blots containing cytoplasmic RNAs from G1-, S-, and arabinofuranosylcytosine (cytosine arabinoside)-treated S-phase cells. In addition, the lambda HHG DNAs were shown to protect in vivo labeled H4 mRNAs from S1 nuclease digestion. Based on the analysis of the lambda HHG clones, human histone genes appear to be clustered in the genome. However, gene clusters do not seem to be present in identical tandem repeats. The lambda HHG clones described in this report fall into at least three distinct types of arrangement. One of these arrangements contains two coding regions for each of the histones H3 and H4. The arrangement of histone genes in the human genome, therefore, appears to be different from that in the sea urchin and Drosophila genomes in which each of the five histone-encoding regions (H1, H2A, H2B, H3, and H4) is present only once in each tandemly repeated cluster. At least one clone, lambda HHG 41, contains, in addition to the histone genes, a region that hybridizes with a cytoplasmic RNA approximately 330 nucleotides in length. This RNA is not similar in size to known histone-encoding RNAs and is present in the cytoplasm of HeLa cells predominantly in the G1 phase of the cell cycle.

Analysis of histone gene expression during the cell cycle in HeLa cells by using cloned human histone genes

Although it is generally agreed that histone protein synthesis is restricted to the S phase of the cell cycle--and therefore parallels DNA replication--both transcriptional and posttranscriptional levels of control have been invoked. Using blot hybridization with several cloned genomic human histone sequences representing different histone gene clusters as probes, we have assessed the steady-state level of histone RNAs in the nucleus and cytoplasm of G1 and S phase HeLa S3 cells. The representation of histone mRNA sequences of G1 compared with S phase cells was less than 1% in the cytoplasm and approximately 1% in the nucleus. These data are consistent with transcriptional control, but we cannot completely dismiss the possibility that regulation of histone gene expression is, to some extent, mediated posttranscriptionally. If histone gene transcription does occur in G1, the RNAs must either be rapidly degraded or be transcribed to a limited extent compared with S phase. An unexpected result was obtained when a blot of cytoplasmic RNA from G1 and S phase cells was hybridized with lambda HHG 41 DNA (containing H3 and H4 human genomic histone sequences). Although hybridization with histone mRNAs was observed for RNAs from S phase but not from G1 cells, hybridization with a nonhistone RNA of approximately 330 nucleotides present predominantly in G1 was also observed.

The region of mouse mammary tumor virus DNA containing the long terminal repeat includes a long coding sequence and signals for hormonally regulated transcription

Starting from a biologically active recombinant DNA clone of exogenous unintegrated GR mouse mammary tumor virus, we have generated three subclones of PstI fragments of 1.45, 1.1, and 2.0 kb in the plasmid vector PBR322. The nucleotide sequence has been determined for the clone of 1.45 kb which includes almost the complete region of the long terminal repeat (LTR) plus an adjacent stretch of unique sequence DNA. A short region of the 2.0 kb clone, containing the beginning of the LTR, has also been sequenced. Starting with the A of an initiation codon outside the LTR, we detected an open reading frame of 960 nucleotides, potentially coding for a protein of 320 amino acids (36K). Two hundred nucleotides downstream from the termination codon, and approximately 25 nucleotides upstream from the presumptive initiation site of viral RNA synthesis, we found a promoter-like sequence. The sequence AGTAAA was detected approximately 15-20 nucleotides upstream from the 3' end of virion RNA and probably serves as a polyadenylation signal. The 1.45 kb PstI fragment has been transfected into Ltk- cells together with a plasmid containing the thymidine kinase gene of herpes simplex virus. The virus-specific RNA synthesis detected in a Tk+ cell clone was strongly stimulated by the addition of dexamethasone.