The National Center for Biotechnology Information (NCBI) provides a large suite of online resources for biological information and data, including the GenBank
nucleic acid sequence database and the ...PubMed database of citations and abstracts for published life science journals. The Entrez system provides search and retrieval operations for most of these data from 37 distinct databases. The E-utilities serve as the programming interface for the Entrez system. Augmenting many of the Web applications are custom implementations of the BLAST program optimized to search specialized data sets. New resources released in the past year include iCn3D, MutaBind, and the Antimicrobial Resistance Gene Reference Database; and resources that were updated in the past year include My Bibliography, SciENcv, the Pathogen Detection Project, Assembly, Genome, the Genome Data Viewer, BLAST and PubChem. All of these resources can be accessed through the NCBI home page at www.ncbi.nlm.nih.gov.
We present an extension of the Minimum Information about any (x) Sequence (MIxS) standard for reporting sequences of uncultivated virus genomes. Minimum Information about an Uncultivated Virus Genome ...(MIUViG) standards were developed within the Genomic Standards Consortium framework and include virus origin, genome quality, genome annotation, taxonomic classification, biogeographic distribution and in silico host prediction. Community-wide adoption of MIUViG standards, which complement the Minimum Information about a Single Amplified Genome (MISAG) and Metagenome-Assembled Genome (MIMAG) standards for uncultivated bacteria and archaea, will improve the reporting of uncultivated virus genomes in public databases. In turn, this should enable more robust comparative studies and a systematic exploration of the global virosphere.
The National Center for Biotechnology Information (NCBI) provides a large suite of online resources for biological information and data, including the GenBank(®) nucleic acid sequence database and ...the PubMed database of citations and abstracts for published life science journals. Additional NCBI resources focus on literature (Bookshelf, PubMed Central (PMC) and PubReader); medical genetics (ClinVar, dbMHC, the Genetic Testing Registry, HIV-1/Human Protein Interaction Database and MedGen); genes and genomics (BioProject, BioSample, dbSNP, dbVar, Epigenomics, Gene, Gene Expression Omnibus (GEO), Genome, HomoloGene, the Map Viewer, Nucleotide, PopSet, Probe, RefSeq, Sequence Read Archive, the Taxonomy Browser, Trace Archive and UniGene); and proteins and chemicals (Biosystems, COBALT, the Conserved Domain Database (CDD), the Conserved Domain Architecture Retrieval Tool (CDART), the Molecular Modeling Database (MMDB), Protein Clusters, Protein and the PubChem suite of small molecule databases). The Entrez system provides search and retrieval operations for many of these databases. Augmenting many of the Web applications are custom implementations of the BLAST program optimized to search specialized data sets. All of these resources can be accessed through the NCBI home page at http://www.ncbi.nlm.nih.gov.
Efficient DNA replication involves coordinated interactions among DNA polymerase, multiple factors, and the DNA. From bacteriophage T4 to eukaryotes, these factors include a helicase to unwind the ...DNA ahead of the replication fork, a single-stranded binding protein (SSB) to bind to the ssDNA on the lagging strand, and a helicase loader that associates with the fork, helicase, and SSB. The previously reported structure of the helicase loader in the T4 system, gene product (gp)59, has revealed an N-terminal domain, which shares structural homology with the high mobility group (HMG) proteins from eukaryotic organisms. Modeling of this structure with fork DNA has suggested that the HMG-like domain could bind to the duplex DNA ahead of the fork, whereas the C-terminal portion of gp59 would provide the docking sites for helicase (T4 gp41), SSB (T4 gp32), and the ssDNA fork arms. To test this model, we have used random and targeted mutagenesis to generate mutations throughout gp59. We have assayed the ability of the mutant proteins to bind to fork, primed fork, and ssDNAs, to interact with SSB, to stimulate helicase activity, and to function in leading and lagging strand DNA synthesis. Our results provide strong biochemical support for the role of the N-terminal gp59 HMG motif in fork binding and the interaction of the C-terminal portion of gp59 with helicase and SSB. Our results also suggest that processive replication may involve the switching of gp59 between its interactions with helicase and SSB.
Replication requires coordinated interactions among proteins/DNA.
Mutational analysis of T4 helicase loader, gp59, identifies domains that interact with DNA and replication factors.
The high mobility group motif of gp59 interacts with the DNA fork; gp59 C-terminal surfaces interact with helicase and single-stranded binding protein.
Processive replication may involve switching of gp59 between interactions with helicase and the single-stranded binding protein.
Chromosomes provide a template for a number of DNA transactions, including replication and transcription, but the dynamic interplay between these activities is poorly understood at the genomic level. ...The bacteriophage T4 has long served as a model for the study of DNA replication, transcription, and recombination, and should be an excellent model organism in which to integrate
in vitro biochemistry into a chromosomal context. As a first step in characterizing the dynamics of chromosomal transactions during T4 infection, we have employed a unique set of macro array strategies to identify the origins of viral DNA synthesis and monitor the actual accumulation of nascent DNA across the genome in real time. We show that T4 DNA synthesis originates from at least five discrete loci within a single population of infected cells, near
oriA,
oriC,
oriE,
oriF, and
oriG, the first direct evidence of multiple, active origins within a single population of infected cells. Although early T4 DNA replication is initiated at defined origins, continued synthesis requires viral recombination. The relationship between these two modes of replication during infection has not been well understood, but we observe that the switch between origin and recombination-mediated replication is dependent on the number of infecting viruses. Finally, we demonstrate that the nascent DNAs produced from origin loci are regulated spatially and temporally, leading to the accumulation of multiple, short DNAs near the origins, which are presumably used to prime subsequent recombination-mediated replication. These results provide the foundation for the future characterization of the molecular dynamics that contribute to T4 genome function and evolution and may provide insights into the replication of other multi origin chromosomes.
Interaction between the adenoassociated virus (AAV) replication proteins, Rep68 and 78, and the viral terminal repeats (TRs) is mediated by a DNA sequence termed the Rep-binding element (RBE). This ...element is necessary for Rep-mediated unwinding of duplex DNA substrates, directs Rep catalyzed cleavage of the AAV origin of DNA replication, and is required for viral transcription and proviral integration. Six discrete Rep complexes with the AAV TR substrates have been observed in vitro, and cross-linking studies suggest these complexes contain one to six molecules of Rep. However, the functional relationship between Rep oligomerization and biochemical activity is unclear. Here we have characterized Rep complexes that form on the AAV TR. Both Rep68 and Rep78 appear to form the same six complexes with the AAV TR, and ATP seems to stimulate formation of specific, higher order complexes. When the sizes of these Rep complexes were estimated on native polyacrylamide gels, the four slower migrating complexes were larger than predicted by an amount equivalent to one or two TRs. To resolve this discrepancy, the molar ratio of protein and DNA was calculated for the three largest complexes. Data from these experiments indicated that the larger complexes included multiple TRs in addition to multiple Rep molecules and that the Rep-to-TR ratio was approximately 2. The two largest complexes were also associated with increased Rep-mediated, origin cleavage activity. Finally, we characterized a second, Rep-mediated cleavage event that occurs adjacent to the normal nicking site, but on the opposite strand. This second site nicking event effectively results in double-stranded DNA cleavage at the normal nicking site.
Viruses of bacteria and archaea impact natural, engineered and human ecosystems, but their study is hampered by the lack of a universal or scalable taxonomic framework. Furthermore we introduce ...vConTACT v2.0, a network-based application to establish prokaryotic virus taxonomy that scales to thousands of uncultivated virus genomes, and integrates distance-based hierarchical clustering and confidence scores for all taxonomic predictions. Performance tests demonstrated significant improvements over the original tool and near-identical (96%) correspondence to current International Committee on Taxonomy of Viruses (ICTV) viral taxonomy where genus-level assignments are available. Beyond these “known viruses”, vConTACT v2.0 suggested automatic genus assignments for 1,364 previously unclassified reference viruses, with perfectly scoring assignments submitted as new taxonomic proposals to ICTV. Scaling experiments with 15,280 global ocean large viral genome fragments demonstrated that the reference network was rapidly scalable and robust to adding large-scale viral metagenomic datasets. Together these efforts provide a critically-needed, systematically classified reference network and an accurate, scalable, and automatable taxonomic analysis tool.
The International Committee on Taxonomy of Viruses (ICTV) is tasked with classifying viruses into taxa (phyla to species) and devising taxon names. Virus names and virus name abbreviations are ...currently not within the ICTV’s official remit and are not regulated by an official entity. Many scientists, medical/veterinary professionals, and regulatory agencies do not address evolutionary questions nor are they concerned with the hierarchical organization of the viral world, and therefore, have limited use for ICTV-devised taxa. Instead, these professionals look to the ICTV as an expert point source that provides the most current taxonomic affiliations of viruses of interests to facilitate document writing. These needs are currently unmet as an ICTV-supported, easily searchable database that includes all published virus names and abbreviations linked to their taxa is not available. In addition, in stark contrast to other biological taxonomic frameworks, virus taxonomy currently permits individual species to have several members. Consequently, confusion emerges among those who are not aware of the difference between taxa and viruses, and because certain well-known viruses cannot be located in ICTV publications or be linked to their species. In addition, the number of duplicate names and abbreviations has increased dramatically in the literature. To solve this conundrum, the ICTV could mandate listing all viruses of established species and all reported unclassified viruses in forthcoming online ICTV Reports and create a searchable webpage using this information. The International Union of Microbiology Societies could also consider changing the mandate of the ICTV to include the nomenclature of all viruses in addition to taxon considerations. With such a mandate expansion, official virus names and virus name abbreviations could be catalogued and virus nomenclature could be standardized. As a result, the ICTV would become an even more useful resource for all stakeholders in virology. Arbovirus; classification; International Committee on Taxonomy of Viruses; (ICTV); nomenclature; species; taxonomy; virus.
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