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[Clone of hepatitis B virus X gene and its protein expression].

OBJECTIVE: To construct the hepatitis B virus (HBV) X gene recombinant and to induce the expression of X protein. METHODS: HBV DNA was extracted from the serum of patient with hepatitis B. The X gene was amplified by PCR using the primers with EcoRI and HindIII digestion sites, and then cloned into pronucleus expression vector pMAL-C2X, which was detected by EcoRI and HindIII digestion and sequence. Finally, the recombinant was induced by IPTG to express X protein in JM109. RESULTS: The band similar to X gene was amplified by PCR. There were fragments similar to X gene when the recombinant was digested by the enzyme digestion. It was tested by DNA sequence that the correct and entire opening reading frame of HBV X gene was inserted. The X protein was expressed by the IPTG induction. CONCLUSION: Pronucleus expression recombinant pMAL-C2X-HBV-X is constructed successfully and with the IPTG induction, the recombinant pMAL-C2X-HBV-X can express the X protein in E. coli JM109, which lays the foundation for the HBV X protein purification and its biological study.

Base Sequence↗

Human linear B-cell epitopes encoded by the hepatitis E virus include determinants in the RNA-dependent RNA polymerase.

Hepatitis E virus is responsible for both sporadic and epidemic hepatitis in developing countries. The nonenveloped virus is 27-34 nm in diameter and has been shown to contain a single-strand, positive-sense, polyadenylylated RNA genome of approximately 7.5 kilobases. The nucleotide sequence of the Burma strain of hepatitis E virus has been reported and three open reading frames (ORFs) have been identified. The deduced amino acid sequence from each of these ORFs was used to synthesize overlapping peptides (decamers overlapping at every fourth amino acid) on a solid phase. These peptides were then tested in an ELISA with pooled acute-phase sera from known cases of enterically transmitted non-A, non-B hepatitis collected in the Sudan. Linear B-cell epitopes were identified in all three ORFs. Epitopes were identified throughout the polyprotein encoded by ORF1, but they appeared to be particularly concentrated in the region of the RNA-dependent RNA polymerase. Distinct epitopes were identified in the presumed structural protein encoded by ORF2, and one epitope was identified close to the carboxyl terminus of the protein encoded by ORF3. These data precisely pinpoint linear B-cell epitopes recognized by antibodies from patients with acute hepatitis E and identify an antibody response directed against the RNA-dependent RNA polymerase.

Amino Acid Sequence↗

The sequence of a 8 kb segment on the right arm of yeast chromosome VII identifies four new open reading frames and the genes for yTAFII145.

We report the sequence of a 8,061 bp fragment of Saccharomyces cerevisiae chromosome VII. Five open reading frames (ORFs) of at least 100 amino acids were identified. Three show similarities to the amino-acid sequence of known gene products. ORF G9374 corresponds to the gene coding for the yTAFII145 protein: a TBP-associated factor whose amino-acid sequence was previously reported (Reese et al., 1994). The remaining ORF does not display similarities to known sequences.

Amino Acid Sequence↗

Analysis of integrated hepatitis B virus DNA and flanking cellular sequences in a childhood hepatocellular carcinoma.

The DNA of tumor tissue K1 obtained at autopsy from a case of hepatocellular carcinoma (HCC) in a 9-year-old boy contained integrated hepatitis B virus (HBV) DNA at a single site in the chromosome (case 2, Chang et al.: Hepatology 13:316-320, 1991). To characterize further the integrated viral DNA sequences, a genomic library of the K1 DNA was constructed in the lambda L47.1 vector. One phage clone, designated KTM-1, containing integrated HBV DNA and cellular flanking sequences was obtained from this library. The restriction map and DNA sequence of this clone showed that the integrated HBV DNA was partially deleted and rearranged. The most conserved viral DNA sequences were surface and X genes and arranged in the opposite orientation. The viral core gene was not present. Using chloramphenicol acetyltransferase (CAT) assay, the C-terminal truncated X open reading frame was demonstrated to retain its trans-activating ability. The result suggested that the functional integrated X gene may play a role in hepatocarcinogenesis. The study also showed that the right cellular flanking sequences were human alphoid repetitive sequences.

Base Sequence↗

RIM2, MSI1 and PGI1 are located within an 8 kb segment of Saccharomyces cerevisiae chromosome II, which also contains the putative ribosomal gene L21 and a new putative essential gene with a leucine zipper motif.

We report the DNA sequence of an 8 kb segment localized on the right arm of chromosome II from Saccharomyces cerevisiae. The sequence reveals the presence of eight open reading frames (ORFs). Three of them, YBR1402, YBR1405 and YBR1406 are previously sequenced genes, respectively the RIM2 (replication in mitochondria), MSI1 (multicopy suppressor of IRA1 gene) and PGI1 (phosphoglucoisomerase) genes. The predicted product of the ORF YBR1401 could be the putative yeast ribosomal protein L21. A new essential gene, YBR1403, has been identified by disruption; it possesses a leucine zipper motif.

Amino Acid Sequence↗

The sequence of an 8.8 kb segment on the left arm of chromosome II from Saccharomyces cerevisiae reveals four new open reading frames including homologs of animal DNA polymerase alpha-primases and bacterial GTP cyclohydrolase II.

The DNA sequence of two contiguous 7648 bp and 1194 bp BamHI fragments from the cosmid alpha 1201 located about 60 kb from the centromere on the left arm of chromosome II from Saccharomyces cerevisiae has been determined. Sequence analysis reveals four new open reading frames longer than 300 bp: YBL0415 (309 bp), YBL0416 (4539 bp), YBL0417 (1035 bp) and YBL0414 (2115 bp), which extends into the neighbouring 5.2 kb BamHI fragment. The YBL0414 shows homologies to the mouse 68 kDa and Drosophila melanogaster 76 kDa subunits of the DNA polymerase alpha-primase complex. The YBL0417 is homologous to bacterial GTP cyclohydrolase II (EC 3.5.4.25).

Amino Acid Sequence↗

Sequence comparison of the ARG4 chromosomal regions from the two related yeasts, Saccharomyces cerevisiae and Saccharomyces douglasii.

A 3.6 kb DNA fragment from Saccharomyces douglasii, containing the ARG4 gene, has been cloned, sequenced and compared to the corresponding region from Saccharomyces cerevisiae. The organization of this region is identical in both yeasts. It contains besides the ARG4 gene, another complete open reading frame (ORF) (YSD83) and a third incomplete one (DED81). The ARG4 and the YSD83 coding regions differ from their S. cerevisiae homologs by 8.1% and 12.5%, respectively, of base substitutions. The encoded proteins have evolved differently: amino acid replacements are significantly less frequent in Arg4 (2.8%) than in Ysc83 (12.4%) and most of the changes in Arg4 are conservative, which is not the case for Ysc83. The non-coding regions are less conserved, with small AT-rich insertions/deletions and 20% base substitutions. However, the level of divergence is smaller in the aligned sequences of these regions than in silent sites of the ORFs, probably revealing a higher degree of constraints. The Gcn4 binding site and the region where meiotic double-strand breaks occur, are fully conserved. The data confirm that these two yeasts are evolutionarily closely related and that comparisons of their sequences might reveal conserved protein and DNA domains not expected to be found in sequence comparisons between more diverged organisms.

Amino Acid Sequence↗

Isolation and sequence determination of cDNA encoding human T-protein of the glycine cleavage system.

We present the full-length cDNA sequence of human T-protein of the glycine cleavage system. Overlapping cDNA clones were isolated by screening human liver cDNA libraries with bovine T-protein cDNA. The 1209 base pair open reading frame encodes 403 amino acid precursor protein, and the deduced amino acid sequence of the mature peptide shows 90 and 68% homology to that of bovine and chicken counterpart, respectively. RNA blot analysis of human liver transcripts and Southern blot analysis of human genomic DNA confirm that human T-protein is encoded by a single gene.

Adult↗

Cloning and characterization of a human cDNA (INPPL1) sharing homology with inositol polyphosphate phosphatases.

We have cloned a novel human cDNA, INPPL1 (GenBank Accession No. L36818), which maps to 11q23. The corresponding mRNA is 4657 nt in length and is widely expressed in both fetal and adult tissues. An open reading frame of 3441 nt encodes a putative polypeptide that shares several domains with inositol triphosphate phosphatases. Several polymorphisms have been mapped to the 3'-untranslated region, yet the putative coding region showed no polymorphisms in nine independent cDNA samples.

Adult↗

Complete nucleotide sequence of sugarcane streak Monogeminivirus.

The complete nucleotide sequence of the genome of the Monogeminivirus sugarcane streak virus (SSV) was determined from cloned replicative form DNA. The genome is contained in one DNA circle of 2,758 nucleotides, and has four open reading frames with the potential to encode proteins of MW > 10 kDa: two in the viral (+) sense and two in the complementary (-) sense. Each open reading frame has a counterpart among the open reading frames reported for other Monogeminiviruses. A potential binding site for a DNA replication primer and potential transcriptional control sequences were identified on the (+) strand, and a possible intron on the (-) strand. Phylogenetic analysis of coat protein and replication-associated protein sequences of SSV and other grass-infecting geminiviruses indicate that SSV, although distinct from any other virus, is part of an "African streak virus subgroup" of Monogeminiviruses.

Base Sequence↗

The complete nucleotide sequence of Passiflora latent virus and its phylogenetic relationship to other carlaviruses.

A virus identified as Passiflora latent virus (PLV) was isolated from passion fruit plants. Particle morphology, host range and serological properties suggested that this virus belongs to the genus Carlavirus. The complete genomic sequence of PLV was determined by sequencing overlapping cDNA fragments. The genome consisted of 8386 nt, excluding the poly (A) tail and contained six open reading frames, typical of carlaviruses. The overall similarities of the predicted amino acid sequence of PLV to those of other carlaviruses ranged from 25 to 73%. Phylogenetic analysis indicated that PLV was closely related to lily symptomless virus and blueberry scorch virus. This is the first report of the complete nucleotide sequence and genome structure of PLV.

Base Sequence↗

Analysis of the HSV-1 strain 17 DNA polymerase gene reveals the expression of four different classes of pol transcripts.

We have investigated the structure and the expression of transcripts of the HSV-1 strain 17 DNA polymerase gene (pol) by various mapping methods including cDNA cloning. The majority of mature pol transcripts is strictly colinear with the pol gene. But additionally, pol cDNAs show a defined heterogeneity in respect to their 5'-terminal regions and can be divided into four classes with characteristic differences; (i) class 1 represents the major transcript (pol-R1) with initiation at HSV-1 positions 62,605-62,610, (ii) class 2 initiates about 70 bp downstream, (iii) class 3 is generated by splicing the short open reading frame (SORF) to a 5'-truncated part of the long open reading frame (LORF) which results in a partially different coding potential, and (iv) class 4 starts 120 bp upstream of the major initiation site in the central part of the origin of replication (oriL). S1 and Exo VII nuclease and RNase protection assays as well as primer extension analyses confirm the classification regarding the genuine structure of pol mRNAs and the differential usage of transcriptional start sites. Furthermore, the transcript classes can be distinguished from each other by their kinetics of appearance/disappearance in the cytoplasm: The first transcription of the pol gene is indicated by the predominant presence of class 2 and class 4 mRNAs at 2 hr postinfection (h.p.i.), followed by an increase of class 1 transcripts up to 4 h.p.i. and a parallel decrease of class 2 mRNAs. These data suggest that expression of the pol gene is finely regulated already at the transcriptional and/or posttranscriptional level prior to the translation of pol mRNAs.

Animals↗

The virulence-determining genomic BamHI fragment 4 of pseudorabies virus contains genes corresponding to the UL15 (partial), UL18, UL19, UL20, and UL21 genes of herpes simplex virus and a putative origin of replication.

The genomic BamHI-fragment 4 of pseudorabies virus (PrV) has previously been shown to encode functions necessary for expression of PrV neurovirulence (B. Lomniczi, S. Watanabe, T. Ben-Porat, and A. S. Kaplan, 1984, J. Virol. 52, 198-205). To identify proteins that might be involved in the neurotropism of PrV we sequenced the complete 9382-bp fragment BamHI-4, the longest contiguous sequence determined in the UL region of PrV so far, and analyzed its coding capacity. In an arrangement similar to that found in herpes simplex virus type 1 we identified complete open reading frames encoding proteins with strong homology to the UL18 (50% homology), UL19 (60% homology), UL20 (33% homology), and UL21 (36% homology) polypeptides and the 3'-part of a gene homologous to UL15 (67% homology) of HSV-1. In addition, a consensus sequence for an alphaherpesviral origin of replication was found at the left terminus of the fragment.

Base Sequence↗

Nucleotide sequence of the nfaA gene encoding the antigen 8786 adhesive factor of enterotoxigenic Escherichia coli.

The nucleotide sequence of a 714-bp DNA fragment containing the enterotoxic Escherichia coli (ETEC) adhesive factor 8786 structural gene, designated nfaA, revealed an open reading frame of 498 bp encoding a polypeptide of 166 amino acids. Primer-extension experiments showed that the nfaA gene is within a single transcription unit. No homology was found with the ETEC adhesive factors already sequenced. In contrast, a homology with Salmonella enteritidis fimbrin SEF 14 was observed.

Adhesins, Escherichia coli↗

Cloning and sequence analysis of the genes encoding phosphotransbutyrylase and butyrate kinase from Clostridium acetobutylicum NCIMB 8052.

An 8.1-kb fragment of chromosomal DNA from Clostridium acetobutylicum NCIMB 8052 (formerly NCIB 8052) has been cloned into plasmid pAT153 and shown to allow the growth of Escherichia coli LJ32 (F+ atoC2c atoD32 fadR) on butyrate as the sole source of carbon and energy. Deletion analysis delineated a 3.9-kb subfragment capable of complementation. The nucleotide sequence of this fragment was determined and it was shown to encode three complete, and two incomplete open reading frames (ORFs). Based on enzymic studies of recombinant clones, two of these ORFs were shown to encode phosphotransbutyrylase and butyrate kinase. The above enzymes are involved in the acidogenic phase of fermentation in C. acetobutylicum. The fragment also carries an incomplete ORF encoding a polypeptide exhibiting substantial similarity to dihydropteroate synthase.

Amino Acid Sequence↗

Cloning, sequencing and regulation of thiA, a thiamin biosynthesis gene from Bacillus subtilis.

The thiA gene is involved in the biosynthesis of the pyrimidine moiety of thiamin in Bacillus subtilis. This gene was cloned using a DNA probe rescued from thiA::Tn917 to screen a B. subtilis genomic library. ThiA exhibits 70% identity with E. coli thiC. The proposed thiA open reading frame complements all available thiA mutants of B. subtilis as well as the thiC mutant of E. coli. This suggests a similar biosynthetic pathway to 2-methyl-4-amino-5-hydroxymethylpyrimidine in both organisms. The expression of thiA is regulated, at least on the transcriptional level, and is significantly repressed by thiamin and 2-methyl-4-amino-5-hydroxymethylpyrimidine.

Amino Acid Sequence↗

Experimental RNomics: identification of 140 candidates for small non-messenger RNAs in the plant Arabidopsis thaliana.

BACKGROUND: Genomes from all organisms known to date express two types of RNA molecules: messenger RNAs (mRNAs), which are translated into proteins, and non-messenger RNAs, which function at the RNA level and do not serve as templates for translation. RESULTS: We have generated a specialized cDNA library from Arabidopsis thaliana to investigate the population of small non-messenger RNAs (snmRNAs) sized 50-500 nt in a plant. From this library, we identified 140 candidates for novel snmRNAs and investigated their expression, abundance, and developmental regulation. Based on conserved sequence and structure motifs, 104 snmRNA species can be assigned to novel members of known classes of RNAs (designated Class I snmRNAs), namely, small nucleolar RNAs (snoRNAs), 7SL RNA, U snRNAs, as well as a tRNA-like RNA. For the first time, 39 novel members of H/ACA box snoRNAs could be identified in a plant species. Of the remaining 36 snmRNA candidates (designated Class II snmRNAs), no sequence or structure motifs were present that would enable an assignment to a known class of RNAs. These RNAs were classified based on their location on the A. thaliana genome. From these, 29 snmRNA species located to intergenic regions, 3 located to intronic sequences of protein coding genes, and 4 snmRNA candidates were derived from annotated open reading frames. Surprisingly, 15 of the Class II snmRNA candidates were shown to be tissue-specifically expressed, while 12 are encoded by the mitochondrial or chloroplast genome. CONCLUSIONS: Our study has identified 140 novel candidates for small non-messenger RNA species in the plant A. thaliana and thereby sets the stage for their functional analysis.

Arabidopsis↗

Molecular, functional, and evolutionary analysis of sequences specific to Salmonella.

In that salmonellae have been implicated in an unprecedented array of diseases, sequences found to be specific to this species are often thought to be involved in the virulence attributes not seen in other enteric bacteria. To identify the molecular, genetic, and phenotypic characteristics that differentiate bacterial species, we analyzed five cloned DNA fragments that were originally described as being confined to Salmonella. Most of these segments mapped to unique positions on the Salmonella typhimurium chromosome indicative of independent evolutionary events, and three had G+C contents considerably lower than that of the Salmonella genome, suggesting that they arose through horizontal transfer. The nucleotide sequence was determined for one of the clones exhibiting an atypical base composition. This 4.9-kb fragment contained an open reading frame with structural similarity to the LysR family of transcriptional regulators. Strains harboring deletions in this region were tested for > 120 phenotypic characteristics including the effects on a collection of environmentally regulated lac gene fusions. In addition, all deletion strains behaved like the wild-type parent when tested for virulence in mice.

Amino Acid Sequence↗