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At least 1,081 records · Page 60Linked to original sources
PubMed2005

Structural polymorphism of the HIV-1 leader region explored by computational methods.

Experimental studies revealed that the elements of the human immunodeficiency virus type 1 (HIV-1) 5'-untranslated leader region (5'-UTR) can fold in vitro into two alternative conformations, branched (BMH) and 'linearized' (LDI) and switch between them to achieve different functionality. In this study we computationally explored in detail, with our massively parallel genetic algorithm (MPGAfold), the propensity of 13 HIV-1 5'-UTRs to fold into the BMH and the LDI conformation types. Besides the BMH conformations these results predict the existence of two functionally equivalent types of LDI conformations. One is similar to what has been shown in vitro to exist in HIV-1 LAI, the other is a novel conformation exemplified by HIV-1 MAL long-distance interactions. These novel MPGAfold results are further corroborated by a consensus probability matrix algorithm applied to a set of 155 HIV-1 sequences. We also have determined in detail the impact of various strain mutations, domain sizes and folds of elongating sequences simulating folding during transcription on HIV-1 RNA secondary structure folding dynamics.

5' Untranslated Regions↗
PubMed2005

dsCheck: highly sensitive off-target search software for double-stranded RNA-mediated RNA interference.

Off-target effects are one of the most serious problems in RNA interference (RNAi). Here, we present dsCheck (http://dsCheck.RNAi.jp/), web-based online software for estimating off-target effects caused by the long double-stranded RNA (dsRNA) used in RNAi studies. In the biochemical process of RNAi, the long dsRNA is cleaved by Dicer into short-interfering RNA (siRNA) cocktails. The software simulates this process and investigates individual 19 nt substrings of the long dsRNA. Subsequently, the software promptly enumerates a list of potential off-target gene candidates based on the order of off-target effects using its novel algorithm, which significantly improves both the efficiency and the sensitivity of the homology search. The website not only provides a rigorous off-target search to verify previously designed dsRNA sequences but also presents 'off-target minimized' dsRNA design, which is essential for reliable experiments in RNAi-based functional genomics.

Algorithms↗
PubMed2005

Independent binding sites of small protein B onto transfer-messenger RNA during trans-translation.

Stalled bacterial ribosomes are freed by transfer-messenger RNA (tmRNA). With the help of small protein B (SmpB), protein synthesis restarts and tmRNA adds a tag to the stalled protein for destruction. The conformation of a 347 nt long tmRNA from a thermophile and its interactions with SmpB were monitored using structural probes. The RNA is highly folded, including the reading frame, with <30% of unpaired residues. Footprints between SmpB and tmRNA are in the elbow of the tRNA domain, in some pseudoknots including one essential for function and in the lower part of the stem exiting the tRNA domain. The footprints outside the tRNA domain are scattered onto the tmRNA sequence, but form a cluster onto its tertiary structure derived from cryo-EM data. Some footprints flank the first triplet to be translated in tmRNA, suggesting that SmpB participates in the insertion of the tmRNA-encoded reading frame into the decoding center. To discriminate between a conformational rearrangement of tmRNA and independent binding sites, surface plasmon resonance was used and has identified three independent binding sites of SmpB on the RNA, including the site on the tRNA domain. Accordingly, SmpB is proposed to move on the tmRNA scaffold during trans-translation.

Base Sequence↗
PubMed2006

Plant MPSS databases: signature-based transcriptional resources for analyses of mRNA and small RNA.

MPSS (massively parallel signature sequencing) is a sequencing-based technology that uses a unique method to quantify gene expression level, generating millions of short sequence tags per library. We have created a series of databases for four species (Arabidopsis, rice, grape and Magnaporthe grisea, the rice blast fungus). Our MPSS databases measure the expression level of most genes under defined conditions and provide information about potentially novel transcripts (antisense transcripts, alternative splice isoforms and regulatory intergenic transcripts). A modified version of MPSS has been used to perform deep profiling of small RNAs from Arabidopsis, and we have recently adapted our database to display these data. Interpretation of the small RNA MPSS data is facilitated by the inclusion of extensive repeat data in our genome viewer. All the data and the tools introduced in this article are available at http://mpss.udel.edu.

Arabidopsis↗
PubMed2006

Alternative splicing regulation at tandem 3' splice sites.

Alternative splicing (AS) constitutes a major mechanism creating protein diversity in humans. Previous bioinformatics studies based on expressed sequence tag and mRNA data have identified many AS events that are conserved between humans and mice. Of these events, approximately 25% are related to alternative choices of 3' and 5' splice sites. Surprisingly, half of all these events involve 3' splice sites that are exactly 3 nt apart. These tandem 3' splice sites result from the presence of the NAGNAG motif at the acceptor splice site, recently reported to be widely spread in the human genome. Although the NAGNAG motif is common in human genes, only a small subset of sites with this motif is confirmed to be involved in AS. We examined the NAGNAG motifs and observed specific features such as high sequence conservation of the motif, high conservation of approximately 30 bp at the intronic regions flanking the 3' splice site and overabundance of cis-regulatory elements, which are characteristic of alternatively spliced tandem acceptor sites and can distinguish them from the constitutive sites in which the proximal NAG splice site is selected. Our findings imply that AS at tandem splice sites and constitutive splicing of the distal NAG are highly regulated.

Alternative Splicing↗
PubMed2006

CorreLogo: an online server for 3D sequence logos of RNA and DNA alignments.

We present an online server that generates a 3D representation of properties of user-submitted RNA or DNA alignments. The visualized properties are information of single alignment columns, mutual information of two alignment positions as well as the position-specific fraction of gaps. The nucleotide composition of both single columns and column pairs is visualized with the help of color-coded 3D bars labeled with letters. The server generates both VRML and JVX output that can be viewed with a VRML viewer or the JavaView applet, respectively. We show that combining these different features of an alignment into one 3D representation is helpful in identifying correlations between bases and potential RNA and DNA base pairs. Significant known correlations between the tRNA 3' anticodon cardinal nucleotide and the extended anticodon were observed, as were correlations within the amino acid acceptor stem and between the cardinal nucleotide and the acceptor stem. The online server can be accessed using the URL http://correlogo.abcc.ncifcrf.gov.

Computer Graphics↗
PubMed2006

Using RNA secondary structures to guide sequence motif finding towards single-stranded regions.

RNA binding proteins recognize RNA targets in a sequence specific manner. Apart from the sequence, the secondary structure context of the binding site also affects the binding affinity. Binding sites are often located in single-stranded RNA regions and it was shown that the sequestration of a binding motif in a double-strand abolishes protein binding. Thus, it is desirable to include knowledge about RNA secondary structures when searching for the binding motif of a protein. We present the approach MEMERIS for searching sequence motifs in a set of RNA sequences and simultaneously integrating information about secondary structures. To abstract from specific structural elements, we precompute position-specific values measuring the single-strandedness of all substrings of an RNA sequence. These values are used as prior knowledge about the motif starts to guide the motif search. Extensive tests with artificial and biological data demonstrate that MEMERIS is able to identify motifs in single-stranded regions even if a stronger motif located in double-strand parts exists. The discovered motif occurrences in biological datasets mostly coincide with known protein-binding sites. This algorithm can be used for finding the binding motif of single-stranded RNA-binding proteins in SELEX or other biological sequence data.

Algorithms↗
PubMed1996

Characterization of a B. subtilis minor isoleucine tRNA deduced from tDNA having a methionine anticodon CAT.

Bacillus subtilis, which belongs to Gram-positive eubacteria, has been predicted to have a minor isoleucine tRNA transcribed from the gene possessing the CAT anticodon, which corresponds to methionine. We isolated this tRNA and determined its sequence including modified nucleotides. Modified nucleotide analyses using TLC, UV, and FAB mass spectroscopy revealed that the first letter of the anticodon is modified to lysidine [4-amino-2-(N6-lysino)-1-beta-d-ribofuranosyl pyrimidine]. As a result, this tRNA agrees with the minor one predicted from the DNA sequence and is thought to decode the isoleucine codon AUA.

Acylation↗
PubMed2006

Characterization of 67 kD laminin receptor, a protein whose gene is overexpressed on treatment of cells with anti-benzo[a]pyrene-7,8-diol-9,10-epoxide.

The molecular mechanisms potentially related to tumorigenesis induced by anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (anti-BPDE) were investigated by suppression subtractive hybridization of the human bronchial epithelial cells (16HBE) carcinoma induced by BPDE-transformed 16HBE cells (16HBE-C). The 67 kD laminin receptor gene (67LR1) is one of the screened overexpressed genes in 16HBE-C cells when compared with 16HBE. In order to understand the main functions of 67LR1 gene, we amplified the full length of 67LR1 gene using reverse transcription-polymerase chain reaction (RT-PCR) method. The amplified gene products were inserted into pcDNA 3.1 Directional TOPO expression vector. We then transfected 16HBE cells with this vector and derived stable transfected 16HBE cell lines containing the 67LR1 gene by using lipofectin and G418 selection protocols. The expression products of transfected genes were analyzed by semiquantitative RT-PCR. Soft agar growth assay was carried out to identify the malignant features of 67LR1 gene. The stable transfected cell lines can form colonies in soft agar. Further, the transfected cells showed morphological changes compared to the control cells, such as the obvious pseudopods. These data suggest that the 67LR1 gene may be related to malignant transformation induced by the anti-BPDE. The 67LR1 protein may be related to the directionality of cell movement.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1994

Identification of lactobacilli from sourdough and description of Lactobacillus pontis sp. nov.

The microflora of sourdough preparations was investigated by examining the physiological characteristics, whole-cell protein patterns, and 16S rRNA sequences of Lactobacillus isolates. Strains isolated from sourdough were placed in the species Lactobacillus brevis, Lactobacillus sanfrancisco, and Lactobacillus reuteri. 16S rRNA sequences were determined for L. brevis, Lactobacillus fructivorans, Lactobacillus fermentum, L. sanfrancisco, and L. reuteri, and oligonucleotide probes for fast specific identification of these sourdough lactobacilli were deduced. The physiological characteristics, protein patterns, and 16S rRNA sequences of these organisms were compared with data for other sourdough lactobacilli and additional reference strains. Strains of a Lactobacillus species were isolated from rye sourdough; these strains may account for most of the flora in sourdough made from wheat or rye. These organisms were differentiated from other sourdough lactobacilli by their protein pattern, 16S rRNA sequence, G + C content, and physiological properties. The 16S rRNA sequence of this species was determined, and we constructed a phylogenetic tree which reflected the relationships of this species to other lactobacilli. This organism is closely related to L. reuteri. A new Lactobacillus species, Lactobacillus pontis, is proposed. The type strain is L. pontis LTH 2587 (= DSM 8475 = LMG 14187). We describe a general strategy in which a polyphasic approach was used to characterize a new species.

Bacterial Proteins↗
PubMed1998

Two new Rahnella genomospecies that cannot be phenotypically differentiated from Rahnella aquatilis.

Fifty-one Rahnella aquatilis and R. aquatilis-like strains from water, snails and human sources were characterized by routine biochemical tests, carbon source utilization tests, DNA relatedness (hydroxyapatite method) and 16S rRNA sequencing. The results of the genetic methods indicated that the strains comprised three closely related species within the genus Rahnella. It was not possible to differentiate R. aquatilis from the two newly recognized species. The new species were therefore given the vernacular names Rahnella genomospecies 2 and Rahnella genomospecies 3.

Animals↗
PubMed1998

Nocardia crassostreae sp. nov., the causal agent of nocardiosis in Pacific oysters.

Seven strains of bacteria were isolated from Pacific oysters, Crassostrea gigas, with a focal or systemic disease. The strains were aerobic, Gram-positive, acid-fast, produced a mycelium which fragmented into irregular rod-like elements, had a peptidoglycan containing meso-diaminopimelic acid, arabinose and galactose as major sugars, mycolic acids with 46-58 carbon atoms and G + C-rich DNA. All of these properties are consistent with the classification of the organisms in the genus Nocardia. A partial sequence of the 16S rRNA gene of isolate NB4H was determined following isolation and cloning of the PCR-amplified gene. The sequence was aligned with those of representative mycolic-acid-containing taxa and a phylogenetic tree was generated using the neighbour-joining method. It was evident from the phylogenetic tree that the three strains tested, RB1, OB3P and NB4H, were identical and belonged to the Nocardia otitidiscaviarum rRNA sub-group. The biochemical, chemical, morphological and physiological properties of the isolates were also essentially identical and served to distinguish them from representative nocardiae. It is, therefore, proposed that the strains isolated from the diseased Pacific oysters be assigned to a new species, Nocardia crassostreae. The type strain is NB4H (= ATCC 700418).

Animals↗
PubMed1998

Desulfotomaculum halophilum sp. nov., a halophilic sulfate-reducing bacterium isolated from oil production facilities.

A halophilic endospore-forming, sulfate-reducing bacterium was isolated from an oilfield brine in France. The strain, designated SEBR 3139, was composed of long, straight to curved rods. It grew in 1-14% NaCl with an optimum at 6%. On the basis of morphological, physiological and phylogenetical characteristics, strain SEBR 3139 should be classified in the genus Desulfotomaculum. However, it is sufficiently different from the hitherto described Desulfotomaculum species to be considered as a new species. Strain SEBR 3139T (= DSM 11559T) represents the first moderate halophilic species of the genus Desulfotomaculum. The name Desulfotomaculum halophilum sp. nov. is proposed.

Base Sequence↗
PubMed1995

Determination and comparative analysis of the small RNA genomic sequences of California encephalitis, Jamestown Canyon, Jerry Slough, Melao, Keystone and Trivittatus viruses (Bunyaviridae, genus Bunyavirus, California serogroup).

The nucleotide sequences of the small (S) genomic RNAs of six California (CAL) serogroup bunyaviruses (Bunyaviridae: genus Bunyavirus) were determined. The S RNAs of two California encephalitis virus strains, two Jamestown Canyon virus strains, Jerry Slough virus, Melao virus, Keystone virus and Trivittatus virus contained the overlapping nucleocapsid (N) and non-structural (NSs) protein open reading frames (ORFs) as described previously for the S RNAs of other CAL serogroup viruses. All N protein ORFs were 708 nucleotides in length and encoded a putative 235 amino acid gene product. The NSs ORFs were found to be of two lengths, 279 and 294 nucleotides, which potentially encode 92 and 97 amino acid proteins, respectively. The complementary termini and a purine-rich sequence in the 3' non-coding region (genome-complementary sense) were highly conserved amongst CAL serogroup bunyavirus S RNAs. Phylogenetic analyses of N ORF sequences indicate that the CAL serogroup bunyaviruses can be divided into three monophyletic lineages corresponding to three of the complexes previously derived by serological classification. The truncated version of the NSs protein, which is found in five CAL serogroup bunyaviruses, appears to have arisen twice during virus evolution.

Amino Acid Sequence↗
PubMed1997

Beet soil-borne virus RNA 2: similarities and dissimilarities to the coat protein gene-carrying RNAs of other furoviruses.

The complete sequence of the 3454 nt of RNA 2 of the Ahlum isolate of beet soil-borne furovirus (BSBV) has been determined starting with two short stretches of cloned cDNA. Unknown parts of the sequence were amplified by means of RT-PCR techniques using combinations of specific and random primers. BSBV RNA 2 is more similar in its genetic organization to potato mop top virus (PMTV) RNA 3 than to any other furoviral RNA, although it is more than 1100 nt longer. Its 3'-end, unlike that of PMTV RNA 3, has the potential to fold into a tRNA-like structure. It contains one large open reading frame for a readthrough protein with a molecular mass of 104 kDa (104K protein) which is interrupted internally by an amber stop codon terminating the coding region for a protein of 19 kDa (19K), most likely the viral coat protein (CP). The readthrough domain of the 104K protein is much larger than that of PMTV, but the N- and C-proximal portions of these domains are similar for the two viruses. No serological relationships were found between the particles of the two viruses, although more than 50% of the amino acid sequences of the putative CPs are identical.

Amino Acid Sequence↗
PubMed2003

DNA-DNA hybridization study of Burkholderia species using genomic DNA macro-array analysis coupled to reverse genome probing.

The present study was aimed at simplifying procedures to delineate species and identify isolates based on DNA-DNA reassociation. DNA macro-arrays harbouring genomic DNA of reference strains of several Burkholderia species were produced. Labelled genomic DNA, hybridized to such an array, allowed multiple relative pairwise comparisons. Based on the relative DNA-DNA relatedness values, a complete data matrix was constructed and the ability of the method to discriminate strains belonging to different species was assessed. This simple approach led successfully to the discrimination of Burkholderia mallei from Burkholderia pseudomallei, but also discriminated Burkholderia cepacia genomovars I and III, Burkholderia multivorans, Burkholderia pyrrocinia, Burkholderia stabilis and Burkholderia vietnamiensis. Present data showed a sufficient degree of congruence with previous DNA-DNA reassociation techniques. As part of a polyphasic taxonomic scheme, this straightforward approach is proposed to improve species definition, especially for application in the rapid screening necessary for large numbers of clinical or environmental isolates.

Bacterial Typing Techniques↗
PubMed2004

FastR: fast database search tool for non-coding RNA.

The discovery of novel non-coding RNAs has been among the most exciting recent developments in Biology. Yet, many more remain undiscovered. It has been hypothesized that there is in fact an abundance of functional non-coding RNA (ncRNA) with various catalytic and regulatory functions. Computational methods tailored specifically for ncRNA are being actively developed. As the inherent signal for ncRNA is weaker than that for protein coding genes, comparative methods offer the most promising approach, and are the subject of our research. We consider the following problem: Given an RNA sequence with a known secondary structure, efficiently compute all structural homologs (computed as a function of sequence and structural similarity) in a genomic database. Our approach, based on structural filters that eliminate a large portion of the database, while retaining the true homologs allows us to search a typical bacterial database in minutes on a standard PC, with high sensitivity and specificity. This is two orders of magnitude better than current available software for the problem.

Algorithms↗