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Complete nucleotide sequence of cherry necrotic rusty mottle virus.

A virus closely related to cherry green ring mottle virus (CGRMV) was isolated from a tree displaying typical symptoms of cherry necrotic rusty mottle disease. We have named this virus cherry necrotic rusty mottle virus (CNRMV) and report here its complete genomic sequence as determined from overlapping cloned cDNAs. CNRMV has a genome of 8,432 nucleotides excluding the 3' poly(A) sequence and codes for 7 significant open reading frames (ORFs). Five of these ORFs are conserved among all fovea-, allexi-, potex- and carlaviruses and code for a methyltransferase/helicase/polymerase polypeptide, the triple gene block movement proteins and the coat protein. Two further ORFs, ORFs 2a and 5a, are nested completely within ORFs 2 and 5, respectively. The putative translation products from these ORFs display sequence similarity with putative translation products from two similarly nested ORFs present in the CGRMV genome. The function of these two ORFs is unknown, nor are they conserved among other related viruses.

Amino Acid Sequence↗

An alternative to the accepted phylogeny of purple bacteria based on 16S rRNA: analyses of the amino acid sequences of cytochromes C2 and C556 from Rhodobacter (Rhodovulum) sulfidophilus.

It is becoming increasingly apparent from complete genome sequences that 16S rRNA data, as currently interpreted, does not provide an unambiguous picture of bacterial phylogeny. In contrast, we have found that analysis of insertions and deletions in the amino acid sequences of cytochrome c2 has some advantages in establishing relationships and that this approach may have broad utility in acquiring a better understanding of bacterial relationships. The amino acid sequences of cytochromes c2 and c556 have been determined in whole or in part from four strains of Rhodobacter sulfidophilus. The cytochrome c2 contains three- and eight-residue insertions as well as a single-residue deletion in common with the large cytochromes c2 but in contrast to the small cytochromes c2 and mitochondrial cytochromes. In addition, the Rb. sulfidophilus protein shares a rare six- to seven-residue insertion with other Rhodobacter cytochromes c2. The cytochrome c556 is a low-spin class II cytochrome c homologous to the greater family of cytochromes c', which are usually high-spin. The similarity of cytochrome c556 to other species of class II cytochromes is consistent with the relationships deduced from comparisons of cytochromes c2. Thus, our results do not support placement of Rb. sulfidophilus in a separate genus, Rhodovulum, which was proposed primarily on the basis of 16S rRNA sequences. Instead, the Rhodobacter cytochromes c2 are distinct from those of other genera and species of purple bacteria and show a different pattern of relationships among species than reported for 16S rRNA.

Amino Acid Sequence↗

Sequence variation in ligand binding sites in proteins.

BACKGROUND: The recent explosion in the availability of complete genome sequences has led to the cataloging of tens of thousands of new proteins and putative proteins. Many of these proteins can be structurally or functionally categorized from sequence conservation alone. In contrast, little attention has been given to the meaning of poorly-conserved sites in families of proteins, which are typically assumed to be of little structural or functional importance. RESULTS: Recently, using statistical free energy analysis of tetratricopeptide repeat (TPR) domains, we observed that positions in contact with peptide ligands are more variable than surface positions in general. Here we show that statistical analysis of TPRs, ankyrin repeats, Cys2His2 zinc fingers and PDZ domains accurately identifies specificity-determining positions by their sequence variation. Sequence variation is measured as deviation from a neutral reference state, and we present probabilistic and information theory formalisms that improve upon recently suggested methods such as statistical free energies and sequence entropies. CONCLUSION: Sequence variation has been used to identify functionally-important residues in four selected protein families. With TPRs and ankyrin repeats, protein families that bind highly diverse ligands, the effect is so pronounced that sequence "hypervariation" alone can be used to predict ligand binding sites.

Binding Sites↗

A status report on the sequencing and annotation of the P. falciparum genome.

Almost 5 years ago, an international consortium of sequencing centers and funding agencies was formed to sequence the genome of the human malaria parasite Plasmodium falciparum. A novel chromosome by chromosome shotgun strategy was devised to sequence this very AT-rich genome. Two of the 14 chromosomes have been completed and the remaining chromosomes are in the final stages of gap closure. The consortium recently developed plans for the annotation and analysis of the complete genome sequence and its publication in 2002.

Animals↗

A pectinmethylesterase gene associated with a heat-stable extract from citrus.

A putative thermostable pectinmethylesterase (TSPME) protein of 36 kDa was isolated from heat-treated citrus finisher pulp. After purification and partial sequencing of the protein, a reverse genetic approach was used to obtain the complete genomic sequence of a new pectinmethylesterase (PME) gene, CsPME4, from Citrus sinensis (L.) Osb. cv. Valencia. The CsPME4 gene contained two exons of 1203 and 690 bp interrupted by a single positionally conserved intron of 1230 bp. A full-length CsPME4 cDNA clone amplified from Valencia orange juice vesicles shared 98% identity with the genomic clone. The encoded protein of the full-length CsPME4 cDNA shared 66 and 39% amino acid identity with the full-length encoded proteins of the citrus PME, CsPME1, and CsPME3, respectively, whereas the predicted mature protein of CsPME4 shared 80 and 61% identity with the predicted mature proteins of CsPME1 and CsPME3, respectively. Southern analysis demonstrated that CsPME4 was present in at least two copies in the Valencia orange genome. Northern analysis revealed that CsPME4 mRNA was accumulated mainly in young and developing tissues of Valencia orange. Several approaches to express recombinant CsPME4 in different systems failed to obtain active protein. Further research will be necessary to successfully express the putative TSPME gene CsPME4 for biochemical characterization.

Amino Acid Sequence↗

A phylogenomic approach to bacterial phylogeny: evidence of a core of genes sharing a common history.

It has been claimed that complete genome sequences would clarify phylogenetic relationships between organisms, but up to now, no satisfying approach has been proposed to use efficiently these data. For instance, if the coding of presence or absence of genes in complete genomes gives interesting results, it does not take into account the phylogenetic information contained in sequences and ignores hidden paralogies by using a BLAST reciprocal best hit definition of orthology. In addition, concatenation of sequences of different genes as well as building of consensus trees only consider the few genes that are shared among all organisms. Here we present an attempt to use a supertree method to build the phylogenetic tree of 45 organisms, with special focus on bacterial phylogeny. This led us to perform a phylogenetic study of congruence of tree topologies, which allows the identification of a core of genes supporting similar species phylogeny. We then used this core of genes to infer a tree. This phylogeny presents several differences with the rRNA phylogeny, notably for the position of hyperthermophilic bacteria.

Computational Biology↗

From gene trees to organismal phylogeny in prokaryotes: the case of the gamma-Proteobacteria.

The rapid increase in published genomic sequences for bacteria presents the first opportunity to reconstruct evolutionary events on the scale of entire genomes. However, extensive lateral gene transfer (LGT) may thwart this goal by preventing the establishment of organismal relationships based on individual gene phylogenies. The group for which cases of LGT are most frequently documented and for which the greatest density of complete genome sequences is available is the gamma-Proteobacteria, an ecologically diverse and ancient group including free-living species as well as pathogens and intracellular symbionts of plants and animals. We propose an approach to multigene phylogeny using complete genomes and apply it to the case of the gamma-Proteobacteria. We first applied stringent criteria to identify a set of likely gene orthologs and then tested the compatibilities of the resulting protein alignments with several phylogenetic hypotheses. Our results demonstrate phylogenetic concordance among virtually all (203 of 205) of the selected gene families, with each of the exceptions consistent with a single LGT event. The concatenated sequences of the concordant families yield a fully resolved phylogeny. This topology also received strong support in analyses aimed at excluding effects of heterogeneity in nucleotide base composition across lineages. Our analysis indicates that single-copy orthologous genes are resistant to horizontal transfer, even in ancient bacterial groups subject to high rates of LGT. This gene set can be identified and used to yield robust hypotheses for organismal phylogenies, thus establishing a foundation for reconstructing the evolutionary transitions, such as gene transfer, that underlie diversity in genome content and organization.

Bacteria↗

Complete nucleotide sequence of tobacco necrosis virus strain DH and genes required for RNA replication and virus movement.

The complete genome sequence of tobacco necrosis virus strain D (Hungarian isolate, TNV-DH) was determined. The genome (3762 nt) has an organization identical to that reported for TNV-D. Highly infectious synthetic transcripts from a full-length TNV-DH cDNA clone were prepared, the first infectious necrovirus transcript reported. This clone was used for reverse genetic studies to map the viral genes required for replication and movement. Protoplast inoculation with delta 22 and delta 82 mutants revealed that both the 22 kDa and 82 kDa gene products are required for RNA replication. Although the products of three small central genes (p7(1), p7a and p7b) were not essential for RNA replication in protoplasts, mutations in these ORFs prevented infection of plants. In contrast, viral RNA accumulation and cell-to-cell movement were observed in the inoculated, but not the systemically infected, leaves of Nicotiana benthamiana challenged with RNA lacking the intact coat protein (CP) gene. These results strongly suggest that p7(1), p7a, p7b and CP are involved in TNV-DH cell-to-cell and long-distance movement, respectively.

Base Sequence↗

Analysis of a new negevirus-like sequence from Bemisia tabaci unveils a potential new taxon linking nelorpi- and centiviruses.

This study presents the complete genome sequence of a novel nege-like virus identified in whiteflies (Bemisia tabaci MEAM1), provisionally designated as whitefly negevirus 1 (WfNgV1). The virus possesses a single-stranded RNA genome comprising 11,848 nucleotides, organized into four open reading frames (ORFs). These ORFs encode the putative RNA-dependent-RNA-polymerase (RdRp, ORF 1), a glycoprotein (ORF 2), a structural protein with homology to those in the SP24 family, (ORF 3), and a protein of unknown function (ORF 4). Phylogenetic analysis focusing on RdRp and SP24 amino acid sequences revealed a close relationship between WfNgV1 and Bemisia tabaci negevirus 1, a negevirus sequence recently discovered in whiteflies from Israel. Both viruses form a clade sharing a most recent common ancestor with the proposed nelorpivirus and centivirus taxa. The putative glycoprotein from ORF 2 and SP24 (ORF 3) of WfNgV1 exhibit the characteristic topologies previously reported for negevirus counterparts. This marks the first reported negevirus-like sequence from whiteflies in the Americas.

Animals↗

Distinct genomic sequence of the CNR/Pcdhalpha genes in chicken.

CNR/Pcdhalpha family proteins have been first identified as a receptor family that corporate with Fyn, a family of the Src family of tyrosine kinase, and known as synaptic cadherins. Here we report the complete genomic sequence and organization of the chicken (Gallus gallus) CNR/Pcdhalpha The total length of chicken CNR/Pcdhalpha is 177kb. The chicken CNR/Pcdhalpha cluster encodes 12 variable and 3 constant exons. The genomic organizations of the chicken, rat, mouse, and human CNR/Pcdhalpha are basically orthologous. The constant-region exons (CP1, CP2, and CP3) are highly conserved between chicken and mammals, with percent identities of 90.9%, 90.7%, and 91.8% at the amino-acid level for chicken versus rat, mouse, and human, respectively. In contrast, the percent identities of the variable-region exons between chicken and mammals were lower: 51.8%, 51.3%, and 52.7%, on average, for chicken versus rat, mouse, and human, respectively, at the amino-acid level. Moreover, the chicken variable-region exons (from v1 to v12) are highly conserved paralogously (91.4%: nucleic acid, 92.4%: amino acid) in comparison with those of mammals. The CG content of each variable exon in the chicken (v1 to v12) is 74% on average and the CpG dinucleotide frequency in each variable-region exon is twice that of mammals. Due to the high CG content, chicken variable exons (from v1 to v12) encode 3 to 4 frame-shifted open reading frames, which span 1.5-3.0kb, in both the sense and anti-sense orientations.

Animals↗

Genome sequence of Oceanobacillus iheyensis isolated from the Iheya Ridge and its unexpected adaptive capabilities to extreme environments.

Oceanobacillus iheyensis HTE831 is an alkaliphilic and extremely halotolerant Bacillus-related species isolated from deep-sea sediment. We present here the complete genome sequence of HTE831 along with analyses of genes required for adaptation to highly alkaline and saline environments. The genome consists of 3.6 Mb, encoding many proteins potentially associated with roles in regulation of intracellular osmotic pressure and pH homeostasis. The candidate genes involved in alkaliphily were determined based on comparative analysis with three Bacillus species and two other Gram-positive species. Comparison with the genomes of other major Gram-positive bacterial species suggests that the backbone of the genus Bacillus is composed of approximately 350 genes. This second genome sequence of an alkaliphilic Bacillus-related species will be useful in understanding life in highly alkaline environments and microbial diversity within the ubiquitous bacilli.

Bacillus↗

Genomic organization and structure of the 3' region of human MUC3: alternative splicing predicts membrane-bound and soluble forms of the mucin.

The MUC3 gene encodes a large, glycosylated mucin produced by intestinal epithelial cells to form a protective barrier against the external environment. Recently published cDNA sequences for the carboxyl-terminal region of MUC3 polypeptide indicated that rodent Muc3 possesses two epidermal growth factor (EGF)-like domains, and putative transmembrane and cytoplasmic domains, whereas the sequence of human MUC3 predicted termination after the first EGF-like domain. Here we describe the complete genomic sequence encompassing the carboxyl terminal region of human MUC3, revealing the boundaries of 11 exons. RT-PCR and cDNA library cloning experiments indicate that the gene is alternatively spliced, yielding a major membrane-bound form as well as multiple soluble forms. Thus, this work indicates that both membrane-bound and soluble MUC3 mucin proteins are produced by alternative splicing of a single gene. A potentially important polymorphism involving a Tyr residue with a proposed role in signalling is described as well.

3' Untranslated Regions↗

Molecular epidemiology of hepatitis B virus in the United Republic of Tanzania.

In the United Republic of Tanzania, 457 voluntary blood donors were enrolled in hepatitis B virus (HBV) serological screening; 4.8% (22/457) carried HBsAg, 13.6% (3/22) of whom were HBeAg-positive. The mean age among HBeAg-negative carriers was 31 years. HBV DNA was detectable in 81.8% (18/22), the mean level was 3.67 (+/-1.77) log copies/ml. Genotype A was determined in 90.9% (20/22) and 18/20 were classified into subgenotype Aa (Asia/Africa). The basal core promoter, precore and partial core nucleotide sequences were analyzed in the 18 strains; T1809/T1812 ("Kozak" sequence) and A/T1888 (encapsidation signal) variants were identified in 100% and 78%, respectively. The complete genome sequencing for one of the Tanzanian strains revealed no recombination. In conclusion, HBV seroprevalence is high among general population in Tanzania, and the HBV/Aa-infection is predominant. The indicated tendency to early HBeAg seroconversion and declining of the viral load should be confirmed further in case-control studies.

Adult↗

The genome sequence of the probiotic intestinal bacterium Lactobacillus johnsonii NCC 533.

Lactobacillus johnsonii NCC 533 is a member of the acidophilus group of intestinal lactobacilli that has been extensively studied for their "probiotic" activities that include, pathogen inhibition, epithelial cell attachment, and immunomodulation. To gain insight into its physiology and identify genes potentially involved in interactions with the host, we sequenced and analyzed the 1.99-Mb genome of L. johnsonii NCC 533. Strikingly, the organism completely lacked genes encoding biosynthetic pathways for amino acids, purine nucleotides, and most cofactors. In apparent compensation, a remarkable number of uncommon and often duplicated amino acid permeases, peptidases, and phosphotransferase-type transporters were discovered, suggesting a strong dependency of NCC 533 on the host or other intestinal microbes to provide simple monomeric nutrients. Genome analysis also predicted an abundance (>12) of large and unusual cell-surface proteins, including fimbrial subunits, which may be involved in adhesion to glycoproteins or other components of mucin, a characteristic expected to affect persistence in the gastrointestinal tract (GIT). Three bile salt hydrolases and two bile acid transporters, proteins apparently critical for GIT survival, were also detected. In silico genome comparisons with the >95% complete genome sequence of the closely related Lactobacillus gasseri revealed extensive synteny punctuated by clear-cut insertions or deletions of single genes or operons. Many of these regions of difference appear to encode metabolic or structural components that could affect the organisms competitiveness or interactions with the GIT ecosystem.

Biological Transport↗

Cloning, expression, and substrate specificity of a fungal chymotrypsin. Evidence for lateral gene transfer from an actinomycete bacterium.

Unlike trypsins, chymotrypsins have not until now been found in fungi. Expressed sequence tag analysis of the deuteromycete Metarhizium anisopliae identified two trypsins (family S1) and a novel chymotrypsin (CHY1). CHY1 resembles actinomycete (bacterial) chymotrypsins (family S2) rather than other eukaryote enzymes (family S1) in being synthesized as a precursor species (374 amino acids, pI/MW: 5.07/38,279) containing a large N-terminal fragment (186 amino acids). Chy1 was expressed in Pichia pastoris yielding an enzyme with a chymotrypsin specificity for branched aliphatic and aromatic C-terminal amino acids. This is predictable as key catalytic residues determining the specificity of Streptomyces griseus chymotrypsins are conserved with CHY1. Mature (secreted) CHY1 (pI/MW: 8.29/18,499) shows closest overall amino acid identity to S. griseus protease C (55%) and clustered with other secreted bacterial S2 chymotrypsins that diverged widely from animal and endocellular bacterial enzymes in phylogenetic trees of the chymotrypsin superfamily. Conversely, actinomycete chymotrypsins are much more closely related to fungal proteases than to other eubacterial sequences. Complete genomes of yeast, gram eubacteria, archaebacteria, and mitochondria do not contain paralogous genes. Expressed sequence tag data bases from other fungi also lack chymotrypsin homologs. In light of this patchy distribution, we conclude that chy1 probably arose by lateral gene transfer from an actinomycete bacterium.

Actinomycetales↗

Comparative sequence analysis of the eastern equine encephalitis virus pathogenic strains FL91-4679 and GA97 to other North American strains.

Eastern equine encephalitis (EEE) virus is a significant public health concern due to the high mortality rates observed in infected humans, equines and game birds. The EEE genomic sequences available prior to this report are based on laboratory strains with unknown passage histories that may contain an array of cell culture adaptations. Here we report the complete genomic sequences of two recently isolated EEE pathogenic strains with low passage histories. FL91-4697 was isolated in Florida from Aedes albopictus mosquitoes and GA97 was derived from brain tissue of a human fatality that occurred in 1997. Sequence alignment of these new genomes with the documented EEE's permitted us to generate a North American consensus sequence and identify regions of significant diversity. Sequence analysis of the FL91-4679 genome was essential to the production of an EEE infectious clone that is being used to create live attenuated vaccine candidates.

Aedes↗

Novelity in GB virus C/hepatitis G virus and its controversy.

Several novel human RNA viruses were identified in 1995-96 and were partially characterized that apparently can cause acute and chronic hepatitis both in monkeys and humans. These new viruses are related to the flavivirus hepatitis C. It is known to be distinct from other human hepatitis viruses (A, B, C, D, E). Three viruses, identified by investigators at Abbott Labs, have been termed GB-A, GB-B and GB-C. GB-A and GB-B are likely tamarin viruses whereas GB-C infects humans only. All these three viruses are the isolates of the same virus termed HGV, which is positive stranded RNA virus. The genomic sequences of these viruses have been determined by different researchers, which were found to be 1600 nucleotide long. Another group at Genelabs Technologies has identified and determined the complete genomic sequence of a virus they termed hepatitis G virus (HGV). Based on genomic sequence comparisons HGV is probably the same as GB-C. It is highly controversial virus regarding pathogenecity, mode of transmission and site of replication.

Acute Disease↗

Sequence diversity of the erythrocyte membrane antigen 1 in various strains of Plasmodium chabaudi.

We have determined the complete genomic sequence of the Plasmodium chabaudi erythrocyte membrane antigen (PcEMA1) in 4 different parasite strains. The gene structure consisted of a short region encoding a signal sequence separated from the main coding region by an intervening sequence. The overall identity of the three P. chabaudi adami deduced protein sequences to their consensus was 100%, 99.8% and 88% for 556KA, DK and DS respectively, with a general pattern of increasing divergence from the N- to the C-terminus. The P. chabaudi chabaudi strain CB was 72% homologous to the P. chabaudi adami consensus sequence. A gene related to PcEMA1, designated PcEMA1-R, has been identified in the genome of P. chabaudi adami but not in P. chabaudi chabaudi. The partial sequence for this gene in P. chabaudi adami strain DS predicts that it could encode a truncated form of PcEMA1, but its status as a pseudogene or an independent, expressed gene has not been resolved.

Amino Acid Sequence↗