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Complete nucleotide sequence of RNA 3 from cucumber mosaic virus (CMV) strain O: comparative study of nucleotide sequences and amino acid sequences among CMV strains O, Q, D and Y.

The complete nucleotide sequence (2217 residues) of RNA 3 of cucumber mosaic virus strain O (CMV-O) was determined. Two open reading frames were identified, encoding a 3A protein (279 amino acid residues) in the 5'-proximal region and a coat protein (218 amino acid residues). The amino acid sequence of the coat protein C terminus was determined directly from purified protein, and confirmed the presence of the coat protein open reading frame in CMV-O RNA 3. Comparison of nucleotide sequences and amino acid sequences of CMV strains O, Q, D and Y indicated the close relationship between these strains. A tRNA-like structure could be adopted by the 3' non-coding region, and this resembled a similar structure in CMV-Q in spite of nucleotide substitutions or deletions.

Amino Acid Sequence↗

HSV infection induces increased transcription of Alu repeated sequences by RNA polymerase III.

The Alu family of repeated sequences is transcribed by both RNA polymerase II and RNA polymerase III. In cells infected with HSV, transcription by polymerase III increases while transcription by polymerase II decreases. By using virus strains carrying mutations in the genes encoding individual regulatory proteins, we have shown that this effect is dependent upon the immediate-early protein ICP27 and occurs by a process distinct from those which regulate viral gene expression. This is the first example of increased transcription of endogenous cellular sequences by RNA polymerase III during infection with a DNA virus.

Cell Nucleus↗

Posttranscriptional defects in beta-globin messenger RNA metabolism in beta-thalassemia: abnormal accumulation of beta-messenger RNA precursor sequences.

The production of beta-globin messenger RNA (mRNA) in beta-thalassemic erythroblasts was studied during pulse-chase incubations with [3H]uridine. Globin [3H]mRNA was quantitated by molecular hybridization to recombinant DNA probes complementary to globin mRNA and mRNA precursor sequences. Each of six patients with beta +-thalassemia produced normal amounts of globin alpha and beta [3H]mRNA during a 20-min pulse incubation, but the beta/alpha [3H]mRNA ratio declined to steady-state levels during a chase incubation, suggesting posttranscriptional defects in beta-globin mRNA metabolism. beta-globin mRNA precursor production was estimated by measurement of [3H]RNA sequences hybridizing to a pure DNA probe containing only the large intervening sequence (intron) of the beta-mRNA precursor. Four of the patients exhibited abnormal accumulation of 3H-beta-intron sequences (2-10 times normal), indicating abnormal posttranscriptional processing. In the remaining two patients, one of whom is known to carry a mutation in the small intron of the beta-globin gene, accumulation of large 3H beta-intron RNA and beta-globin [3H]mRNA was normal in nuclei, but the ratio of beta/alpha [3H]mRNA in cytoplasm was reduced, suggesting a different posttranscriptional defect in beta-mRNA processing. These findings imply the existence of heterogeneous posttranscriptional abnormalities in beta-globin mRNA metabolism in different patients with beta-thalassemia. The initial rates of gamma- and delta-mRNA synthesis were low in all patients, suggesting that the low level of expression of these genes in adults is mediated at the transcriptional level.

Adolescent↗

The nucleotide sequence of RNA 2 of barley yellow mosaic virus.

The complete nucleotide sequence of RNA 2 of a German isolate of barley yellow mosaic virus (BaYMV) has been determined. The RNA is 3585 nucleotides in length excluding a 3'-terminal poly(A) tail. The viral plus and minus strands in all three reading frames contained only one large open reading frame which started at positions 156 to 158 and terminated with a UAG codon at positions 2828 to 2830, thus encoding an Mr 98,000 polypeptide. Comparisons with sequences of other viruses revealed that the amino terminus of the polypeptide has homology with the proteolytic domain of the helper component proteinase of several potyviruses. It was determined that the 98K protein is a polyprotein composed of an amino-terminal 28K protein and a 70K protein.

Amino Acid Sequence↗

Molecular and structural basis of hemagglutination in mengovirus.

The molecular and structural basis of mengovirus hemagglutination (HA) was investigated by the comparison of nucleotide sequences of the entire capsid coding regions of an HA+ variant, two HA- mutants, 205 and 280, and two HA+ revertants of 205. The mutants were selected after acridine mutagenesis of mengovirus-37A, a heat-stable and HA+ variant that is neurotropic in mice. HA+ revertants of mutant 205 were isolated from brain tissue of mice inoculated with mutant 205. The nucleotide sequences were determined by consensus RNA sequencing using genomic RNA templates from purified virions. Two nucleotide differences were observed in the VP1 coding region of the RNA genomes of mutants 205 and 280 in comparison to the RNA sequences of 37A and the revertants. Interpretation of these data predict substitutions of two consecutive amino acids at residues 1231 (K to R) and 1232 (P to S) of VP1 which form part of the H-I loop of VP1 found at the icosahedral fivefold axis. Analysis of the amino acid substitutions in the context of the three-dimensional structure of the mengovirus-M capsid indicated that hemagglutination most likely involves residues found at the icosahedral fivefold axis and probably does not involve the residues that form the putative cellular receptor binding site (the "pit"). Eleven amino acid differences were observed between the structural proteins of mengovirus-M and 37A, five in VP1, three in VP2, and three in VP3.

Amino Acid Sequence↗

Nucleotide sequence of RNA 3 of peanut stunt cucumovirus.

The nucleotide sequence of the RNA 3 of the peanut stunt virus strain J (PSV-J) was determined and compared with those of the cucumber mosaic virus strain Y (CMV-Y, subgroup I) and the tomato aspermy virus strain C (TAV-C) at both the nucleotide and protein levels. The RNA 3 of PSV-J consists of 2186 nucleotides and has two large open reading frames (ORFs). By analogy to other tripartite plant viruses, it is presumed that the first ORF (867 nucleotides) codes for the 3a protein and the second ORF (654 nucleotides) is the cistron of the coat protein which is expressed from subgenomic RNA 4 of 1010 nt residues. At the nucleotide level, PSV-J RNA 3 shows 60.6% homology to RNA 3 of CMV-Y and 66.3% to that of TAV-C, much lower than the value between the two CMV subgroups. For the 3a proteins there is 65.4% homology between PSV-J and CMV-Y and 70.2% homology between PSV-J and TAV-C. Although it has been known that PSV shows a distant serological relationship to CMV, the coat protein of PSV-J shows only 50% homology with that of CMV-Y.

Amino Acid Sequence↗

Evaluation of 7SL RNA gene sequences for the identification of Leishmania spp.

We evaluated the use of 7SL RNA gene sequences for the identification of Leishmania spp. A fragment (approximately 137 basepairs) of the 7SL RNA gene from 13 reference strains and 18 clinical isolates of 11 different Leishmania species was amplified and sequenced using conserved primers. Reference strains from each Leishmania spp. complex showed unique sequences. The nucleotide sequences were compared pairwise and a range of 81.0-99.3% intercomplex similarity was observed. Clinical isolates of the same species had sequences identical to the corresponding reference strains; thus, the intraspecies similarity was 100%. A phylogenetic tree derived from the 7SL RNA gene partial sequences was constructed and is in agreement with accepted phylogenetic schemes.

Animals↗

Nucleotide sequence of shallot virus X RNA reveals a 5'-proximal cistron closely related to those of potexviruses and a unique arrangement of the 3'-proximal cistrons.

The 8890 nucleotide RNA sequence of shallot virus X (ShVX), a new virus isolated from shallot, has been determined. The sequence contains six open reading frames (ORFs) which encode putative proteins (in the 5' to 3' direction) of M(r) 194528 (ORF1), 26333 (ORF2), 11245 (ORF3), 42209 (ORF4), 28486 (ORF5) and 14741 (ORF6). The ORF1 protein was found to be highly homologous to the putative potexvirus RNA replicases; ORF2, -3, -5 and -6 proteins also have analogues among the potex- and/or carlavirus-encoded proteins. ORF3 is followed by an AUG-lacking frame coding for an amino acid sequence homologous to that of the 7K to 8K proteins of the triple gene block of the above-mentioned viruses. The putative ORF4 protein has no reliable homology with proteins in the database. The results obtained testify that, except for the unique 42K protein gene, the ShVX genome combines a number of elements typical of both carla- and potexviruses.

Amino Acid Sequence↗

Insights on the diversity within a "species" of Thalassicolla (Spumellarida) based on 16S-like ribosomal RNA gene sequencing.

We compared 16S-like ribosomal RNA (rRNA) coding regions of samples of the solitary spumellarian radiolarian Thalassicolla nucleata collected from the Sargasso Sea and the Pacific Ocean. Sequences derived from these locations showed variability in both length and base-pair composition. This level of sequence variability is similar to the degree of variability reported in the literature for species- or even genus-level distinctions. Explanations for our results include multiple alleles for the rRNA gene, or the existence of multiple species of Thalassicolla that are morphologically indistinguishable. The seven existing descriptions of Thalassicolla species, including T. nucleata, are discussed in view of these molecular findings and with reference to our current understanding of the physiology and life cycle of the spumellarian radiolaria.

Animals↗

A hepatitis A virus deletion mutant which lacks the first pyrimidine-rich tract of the 5' nontranslated RNA remains virulent in primates after direct intrahepatic nucleic acid transfection.

Cell culture-adapted variants of hepatitis A virus (HAV) in which the first pyrimidine-rich tract (pY1; nucleotides 99 to 138) of the 5' nontranslated region has been deleted (delta 96-137 or delta 96-139) replicate as well as parental virus in cultured cells (D.R. Shaffer, E.A. Brown, and S.M. Lemon, J. Virol. 68:5568-5578, 1994). To determine whether viruses with such large deletion mutations are able to replicate and to produce acute hepatitis in primates, we reconstructed the delta 96-137 deletion in the genetic background of a virulent virus which differs from the wild type by only one mutation in the 2B-coding region (HM175/8Y). Full-length synthetic delta 96-137/8Y RNA was injected into the livers of two HAV-seronegative marmosets (Saguinus mystax). Both animals developed serum liver enzyme elevations and inflammatory changes in serial liver biopsies within 3 to 4 weeks of inoculation which were comparable in magnitude to those observed previously following intrahepatic inoculation of marmosets with HM175/8Y RNA. Sequencing of RNA from virus shed in feces demonstrated the presence of the delta 96-137 deletion. These results indicate that the pY1 sequence of HAV is not required for efficient viral replication in hepatocytes in situ or for production of acute hepatic injury following intrahepatic RNA transfection in primates.

Animals↗

Molecular phylogenetic studies on an unnamed bovine Babesia sp. based on small subunit ribosomal RNA gene sequences.

The 18S small subunit ribosomal RNA (18S rRNA) gene of an unnamed Babesia species (designated B. U sp.) was sequenced and analyzed in an attempt to distinguish it from other Babesia species in China. The target DNA segment was amplified by polymerase chain reaction (PCR). The PCR product was ligated to the pGEM-T Easy vector for sequencing. It was found that the length of the 18S rRNA gene of all B. U sp. Kashi 1 and B. U sp. Kashi 2 was 1699 bp and 1689 bp. Two phylogenetic trees were, respectively, inferred based on 18S rRNA sequence of the Chinese bovine Babesia isolates and all of Babesia species available in GenBank. The first tree showed that B. U sp. was situated in the branch between B. major Yili and B. bovis Shannxian, and the second tree revealed that B. U sp. was confined to the same group as B. caballi. The percent identity of B. U sp. with other Chinese Babesia species was between 74.2 and 91.8, while the percent identity between two B. U sp. isolates was 99.7. These results demonstrated that this B. U sp. is different from other Babesia species, but that two B. U sp. isolates obtained with nymphal and adultal Hyalomma anatolicum anatolicum tick belong to the same species.

Animals↗

Reverse taxonomy: an approach towards determining the diversity of meiobenthic organisms based on ribosomal RNA signature sequences.

Organisms living in or on the sediment layer of water bodies constitute the benthos fauna, which is known to harbour a large number of species of diverse taxonomic groups. The benthos plays a significant role in the nutrient cycle and it is, therefore, of high ecological relevance. Here, we have explored a DNA-taxonomic approach to access the meiobenthic organismic diversity, by focusing on obtaining signature sequences from a part of the large ribosomal subunit rRNA (28S), the D3-D5 region. To obtain a broad representation of taxa, benthos samples were taken from 12 lakes in Germany, representing different ecological conditions. In a first approach, we have extracted whole DNA from these samples, amplified the respective fragment by PCR, cloned the fragments and sequenced individual clones. However, we found a relatively large number of recombinant clones that must be considered PCR artefacts. In a second approach we have, therefore, directly sequenced PCR fragments that were obtained from DNA extracts of randomly picked individual organisms. In total, we have obtained 264 new unique sequences, which can be readily placed into taxon groups, based on phylogenetic comparison with currently available database sequences. The group with the highest taxon abundance were nematodes and protozoa, followed by chironomids. However, we find also that we have by far not exhausted the diversity of organisms in the samples. Still, our data provide a framework within which a meiobenthos DNA signature sequence database can be constructed, that will allow to develop the necessary techniques for studying taxon diversity in the context of ecological analysis. Since many taxa in our analysis are initially only identified via their signature sequences, but not yet their morphology, we propose to call this approach 'reverse taxonomy'.

Animals↗

Group G beta-hemolytic streptococcal bacteremia characterized by 16S ribosomal RNA gene sequencing.

Little is known about the relative importance of the four species of Lancefield group G beta-hemolytic streptococci in causing bacteremia and the factors that determine the outcome for patients with group G beta-hemolytic streptococcal bacteremia. From 1997 to 2000, 75 group G beta-hemolytic streptococcal strains were isolated from the blood cultures of 66 patients. Sequencing of the 16S rRNA genes of the group G beta-hemolytic streptococci showed that all 75 isolates were Streptococcus dysgalactiae subspecies equisimilis. The API system (20 STREP) and Vitek system (GPI) successfully identified 65 (98.5%) and 62 (93.9%) isolates, respectively, as S. dysgalactiae subspecies equisimilis with >95% confidence, whereas the ATB Expression system (ID32 STREP) only successfully identified 49 isolates (74.2%) as S. dysgalactiae subspecies equisimilis with >95% confidence. The median age of the patients was 76 years (range, 33 to 99 years). Fifty-six patients (85%) were over 60 years old. All patients had underlying diseases. No source of the bacteremia was identified (primary bacteremia) in 34 patients (52%), whereas 17 (26%) had cellulitis and 8 (12%) had bed sore or wound infections. Fifty-eight patients (88%) had community-acquired group G streptococcal bacteremia. Sixty-two patients (94%) had group G Streptococcus recovered in one blood culture, whereas 4 patients (6%) had it recovered in multiple blood cultures. Fifty-nine patients (89%) had group G Streptococcus as the only bacterium recovered in their blood cultures, whereas in 7 patients other bacteria were recovered concomitantly with the group G Streptococcus in the blood cultures (Staphylococcus aureus in 3, Clostridium perfringens in 2, Citrobacter freundii in 1, and Bacteroides fragilis in 1). Overall, 10 patients (15%) died. Male sex, diagnosis other than cellulitis, hospital-acquired bacteremia, and multiple positive blood cultures were associated with mortality [P < 0.005 (relative risk [RR] = 7.6), P < 0.05 (RR = 3.7), P < 0.005 (RR = 5.6), and P < 0.05 (RR = 5.6), respectively]. Unlike group C beta-hemolytic streptococcal bacteremia, group G beta-hemolytic streptococcal bacteremia is not a zoonotic infection in Hong Kong.

Adult↗

HIV-1 structural gene expression requires binding of the Rev trans-activator to its RNA target sequence.

Expression of human immunodeficiency virus type 1 structural proteins requires both the viral Rev trans-activator and its cis-acting RNA target sequence, the Rev response element (RRE). The RRE has been mapped to a conserved region of the HIV-1 env gene and is predicted to form a complex, highly stable RNA stem-loop structure. Site-directed mutagenesis was used to define a small subdomain of the RRE, termed stem-loop II, that is essential for biological activity. Gel retardation assays demonstrated that the Rev trans-activator is a sequence-specific RNA binding protein. The RRE stem-loop II subdomain was found to be both necessary and sufficient for the binding of Rev by the RRE. We propose that the HIV-1 Rev trans-activator belongs to a new class of sequence-specific RNA binding proteins characterized by the presence of an arginine-rich binding motif.

Animals↗

The Subviral RNA Database: a toolbox for viroids, the hepatitis delta virus and satellite RNAs research.

BACKGROUND: Viroids, satellite RNAs, satellites viruses and the human hepatitis delta virus form the 'brotherhood' of the smallest known infectious RNA agents, known as the subviral RNAs. For most of these species, it is generally accepted that characteristics such as cell movement, replication, host specificity and pathogenicity are encoded in their RNA sequences and their resulting RNA structures. Although many sequences are indexed in publicly available databases, these sequence annotation databases do not provide the advanced searches and data manipulation capability for identifying and characterizing subviral RNA motifs. DESCRIPTION: The Subviral RNA database is a web-based environment that facilitates the research and analysis of viroids, satellite RNAs, satellites viruses, the human hepatitis delta virus, and related RNA sequences. It integrates a large number of Subviral RNA sequences, their respective RNA motifs, analysis tools, related publication links and additional pertinent information (ex. links, conferences, announcements), allowing users to efficiently retrieve and analyze relevant information about these small RNA agents. CONCLUSION: With its design, the Subviral RNA Database could be considered as a fundamental building block for the study of these related RNAs. It is freely available via a web browser at the URL: http://subviral.med.uottawa.ca.

Base Sequence↗

Role of the 5'-proximal stem-loop structure of the 5' untranslated region in replication and translation of hepatitis C virus RNA.

Sequences of the untranslated regions at the 5' and 3' ends (5'UTR and 3'UTR) of the hepatitis C virus (HCV) RNA genome are highly conserved and contain cis-acting RNA elements for HCV RNA replication. The HCV 5'UTR consists of two distinct RNA elements, a short 5'-proximal stem-loop RNA element (nucleotides 1 to 43) and a longer element of internal ribosome entry site. To determine the sequence and structural requirements of the 5'-proximal stem-loop RNA element in HCV RNA replication and translation, a mutagenesis analysis was preformed by nucleotide deletions and substitutions. Effects of mutations in the 5'-proximal stem-loop RNA element on HCV RNA replication were determined by using a cell-based HCV replicon replication system. Deletion of the first 20 nucleotides from the 5' end resulted in elimination of cell colony formation. Likewise, disruption of the 5'-proximal stem-loop by nucleotide substitutions abolished the ability of HCV RNA to induce cell colony formation. However, restoration of the 5'-proximal stem-loop by compensatory mutations with different nucleotides rescued the ability of the subgenomic HCV RNA to replicate in Huh7 cells. In addition, deletion and nucleotide substitutions of the 5'-proximal stem-loop structure, including the restored stem-loop by compensatory mutations, all resulted in reduction of translation by two- to fivefold, suggesting that the 5'-proximal stem-loop RNA element also modulates HCV RNA translation. These findings demonstrate that the 5'-proximal stem-loop of the HCV RNA is a cis-acting RNA element that regulates HCV RNA replication and translation.

5' Untranslated Regions↗

Thermo-tolerant Campylobacter fetus bacteraemia identified by 16S ribosomal RNA gene sequencing: an emerging pathogen in immunocompromised patients.

Eight Campylobacter isolates that were able to grow at 25 degrees C and 42 degrees C and had the same biochemical profile were isolated from the blood of eight immunocompromised patients. Conventional biochemical tests were unable to determine whether they were isolates of thermo-tolerant C. fetus, H2S-negative C hyointestinalis, or a new Campylobacter species. Sequencing of the 16S ribosomal RNA genes showed that all eight isolates had the same nucleotide sequence and this was identical to that of C. fetus (GenBank accession no. AF219233). All eight patients had underlying disease and two died despite antibiotic treatment. Because of the ability of C fetus to grow over a wide range of temperatures and a higher incidence of bacteraemia by this organism than C. jejuni in the past 5 years in Hong Kong, thermo-tolerant C fetus may be an emerging pathogen in immunocompromised patients in the years to come.

Aged↗

STRAL: progressive alignment of non-coding RNA using base pairing probability vectors in quadratic time.

MOTIVATION: Alignment of RNA has a wide range of applications, for example in phylogeny inference, consensus structure prediction and homology searches. Yet aligning structural or non-coding RNAs (ncRNAs) correctly is notoriously difficult as these RNA sequences may evolve by compensatory mutations, which maintain base pairing but destroy sequence homology. Ideally, alignment programs would take RNA structure into account. The Sankoff algorithm for the simultaneous solution of RNA structure prediction and RNA sequence alignment was proposed 20 years ago but suffers from its exponential complexity. A number of programs implement lightweight versions of the Sankoff algorithm by restricting its application to a limited type of structure and/or only pairwise alignment. Thus, despite recent advances, the proper alignment of multiple structural RNA sequences remains a problem. RESULTS: Here we present StrAl, a heuristic method for alignment of ncRNA that reduces sequence-structure alignment to a two-dimensional problem similar to standard multiple sequence alignment. The scoring function takes into account sequence similarity as well as up- and downstream pairing probability. To test the robustness of the algorithm and the performance of the program, we scored alignments produced by StrAl against a large set of published reference alignments. The quality of alignments predicted by StrAl is far better than that obtained by standard sequence alignment programs, especially when sequence homologies drop below approximately 65%; nevertheless StrAl's runtime is comparable to that of ClustalW.

Algorithms↗