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  • 1
    Online Resource
    Online Resource
    Mimivirus shows dramatic genome reduction after intraamoebal culture
    Proceedings of the National Academy of Sciences ; 2011
    In:  Proceedings of the National Academy of Sciences Vol. 108, No. 25 ( 2011-06-21), p. 10296-10301
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 108, No. 25 ( 2011-06-21), p. 10296-10301
    Abstract: Most phagocytic protist viruses have large particles and genomes as well as many laterally acquired genes that may be associated with a sympatric intracellular life (a community-associated lifestyle with viruses, bacteria, and eukaryotes) and the presence of virophages. By subculturing Mimivirus 150 times in a germ-free amoebal host, we observed the emergence of a bald form of the virus that lacked surface fibers and replicated in a morphologically different type of viral factory. When studying a 0.40-μm filtered cloned particle, we found that its genome size shifted from 1.2 (M1) to 0.993 Mb (M4), mainly due to large deletions occurring at both ends of the genome. Some of the lost genes are encoding enzymes required for posttranslational modification of the structural viral proteins, such as glycosyltransferases and ankyrin repeat proteins. Proteomic analysis allowed identification of three proteins, probably required for the assembly of virus fibers. The genes for two of these were found to be deleted from the M4 virus genome. The proteins associated with fibers are highly antigenic and can be recognized by mouse and human antimimivirus antibodies. In addition, the bald strain (M4) was not able to propagate the sputnik virophage. Overall, the Mimivirus transition from a sympatric to an allopatric lifestyle was associated with a stepwise genome reduction and the production of a predominantly bald virophage resistant strain. The new axenic ecosystem allowed the allopatric Mimivirus to lose unnecessary genes that might be involved in the control of competitors.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1101118108
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2011
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  • 2
    Online Resource
    Online Resource
    Structure of faustovirus, a large dsDNA virus
    Proceedings of the National Academy of Sciences ; 2016
    In:  Proceedings of the National Academy of Sciences Vol. 113, No. 22 ( 2016-05-31), p. 6206-6211
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 113, No. 22 ( 2016-05-31), p. 6206-6211
    Abstract: Many viruses protect their genome with a combination of a protein shell with or without a membrane layer. Here we describe the structure of faustovirus, the first DNA virus (to our knowledge) that has been found to use two protein shells to encapsidate and protect its genome. The crystal structure of the major capsid protein, in combination with cryo-electron microscopy structures of two different maturation stages of the virus, shows that the outer virus shell is composed of a double jelly-roll protein that can be found in many double-stranded DNA viruses. The structure of the repeating hexameric unit of the inner shell is different from all other known capsid proteins. In addition to the unique architecture, the region of the genome that encodes the major capsid protein stretches over 17,000 bp and contains a large number of introns and exons. This complexity might help the virus to rapidly adapt to new environments or hosts.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1523999113
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2016
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
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  • 3
    Online Resource
    Online Resource
    Provirophages and transpovirons as the diverse mobilome of giant viruses
    Proceedings of the National Academy of Sciences ; 2012
    In:  Proceedings of the National Academy of Sciences Vol. 109, No. 44 ( 2012-10-30), p. 18078-18083
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 109, No. 44 ( 2012-10-30), p. 18078-18083
    Abstract: A distinct class of infectious agents, the virophages that infect giant viruses of the Mimiviridae family, has been recently described. Here we report the simultaneous discovery of a giant virus of Acanthamoeba polyphaga (Lentille virus) that contains an integrated genome of a virophage (Sputnik 2), and a member of a previously unknown class of mobile genetic elements, the transpovirons. The transpovirons are linear DNA elements of ∼7 kb that encompass six to eight protein-coding genes, two of which are homologous to virophage genes. Fluorescence in situ hybridization showed that the free form of the transpoviron replicates within the giant virus factory and accumulates in high copy numbers inside giant virus particles, Sputnik 2 particles, and amoeba cytoplasm. Analysis of deep-sequencing data showed that the virophage and the transpoviron can integrate in nearly any place in the chromosome of the giant virus host and that, although less frequently, the transpoviron can also be linked to the virophage chromosome. In addition, integrated fragments of transpoviron DNA were detected in several giant virus and Sputnik genomes. Analysis of 19 Mimivirus strains revealed three distinct transpovirons associated with three subgroups of Mimiviruses. The virophage, the transpoviron, and the previously identified self-splicing introns and inteins constitute the complex, interconnected mobilome of the giant viruses and are likely to substantially contribute to interviral gene transfer.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1208835109
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2012
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    The louse-borne human pathogen Bartonella quintana is a genomic derivative of the zoonotic agent Bartonella henselae
    Proceedings of the National Academy of Sciences ; 2004
    In:  Proceedings of the National Academy of Sciences Vol. 101, No. 26 ( 2004-06-29), p. 9716-9721
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 101, No. 26 ( 2004-06-29), p. 9716-9721
    Abstract: We present the complete genomes of two human pathogens, Bartonella quintana (1,581,384 bp) and Bartonella henselae (1,931,047 bp). The two pathogens maintain several similarities in being transmitted by insect vectors, using mammalian reservoirs, infecting similar cell types (endothelial cells and erythrocytes) and causing vasculoproliferative changes in immunocompromised hosts. A primary difference between the two pathogens is their reservoir ecology. Whereas B. quintana is a specialist, using only the human as a reservoir, B. henselae is more promiscuous and is frequently isolated from both cats and humans. Genome comparison elucidated a high degree of overall similarity with major differences being B. henselae specific genomic islands coding for filamentous hemagglutinin, and evidence of extensive genome reduction in B. quintana , reminiscent of that found in Rickettsia prowazekii . Both genomes are reduced versions of chromosome I from the highly related pathogen Brucella melitensis . Flanked by two rRNA operons is a segment with similarity to genes located on chromosome II of B. melitensis , suggesting that it was acquired by integration of megareplicon DNA in a common ancestor of the two Bartonella species. Comparisons of the vector-host ecology of these organisms suggest that the utilization of host-restricted vectors is associated with accelerated rates of genome degradation and may explain why human pathogens transmitted by specialist vectors are outnumbered by zoonotic agents, which use vectors of broad host ranges.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0305659101
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2004
    detail.hit.zdb_id: 209104-5
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    SSG: 11
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Giant Marseillevirus highlights the role of amoebae as a melting pot in emergence of chimeric microorganisms
    Proceedings of the National Academy of Sciences ; 2009
    In:  Proceedings of the National Academy of Sciences Vol. 106, No. 51 ( 2009-12-22), p. 21848-21853
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 106, No. 51 ( 2009-12-22), p. 21848-21853
    Abstract: Giant viruses such as Mimivirus isolated from amoeba found in aquatic habitats show biological sophistication comparable to that of simple cellular life forms and seem to evolve by similar mechanisms, including extensive gene duplication and horizontal gene transfer (HGT), possibly in part through a viral parasite, the virophage. We report here the isolation of “Marseille” virus, a previously uncharacterized giant virus of amoeba. The virions of Marseillevirus encompass a 368-kb genome, a minimum of 49 proteins, and some messenger RNAs. Phylogenetic analysis of core genes indicates that Marseillevirus is the prototype of a family of nucleocytoplasmic large DNA viruses (NCLDV) of eukaryotes. The genome repertoire of the virus is composed of typical NCLDV core genes and genes apparently obtained from eukaryotic hosts and their parasites or symbionts, both bacterial and viral. We propose that amoebae are “melting pots” of microbial evolution where diverse forms emerge, including giant viruses with complex gene repertoires of various origins.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0911354106
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2009
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Yaravirus: A novel 80-nm virus infecting Acanthamoeba castellanii
    Proceedings of the National Academy of Sciences ; 2020
    In:  Proceedings of the National Academy of Sciences Vol. 117, No. 28 ( 2020-07-14), p. 16579-16586
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 28 ( 2020-07-14), p. 16579-16586
    Abstract: Here we report the discovery of Yaravirus, a lineage of amoebal virus with a puzzling origin and evolution. Yaravirus presents 80-nm-sized particles and a 44,924-bp dsDNA genome encoding for 74 predicted proteins. Yaravirus genome annotation showed that none of its genes matched with sequences of known organisms at the nucleotide level; at the amino acid level, six predicted proteins had distant matches in the nr database. Complimentary prediction of three-dimensional structures indicated possible function of 17 proteins in total. Furthermore, we were not able to retrieve viral genomes closely related to Yaravirus in 8,535 publicly available metagenomes spanning diverse habitats around the globe. The Yaravirus genome also contained six types of tRNAs that did not match commonly used codons. Proteomics revealed that Yaravirus particles contain 26 viral proteins, one of which potentially representing a divergent major capsid protein (MCP) with a predicted double jelly-roll domain. Structure-guided phylogeny of MCP suggests that Yaravirus groups together with the MCPs of Pleurochrysis endemic viruses. Yaravirus expands our knowledge of the diversity of DNA viruses. The phylogenetic distance between Yaravirus and all other viruses highlights our still preliminary assessment of the genomic diversity of eukaryotic viruses, reinforcing the need for the isolation of new viruses of protists.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.2001637117
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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