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1.
Viruses ; 11(12)2019 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-31817897

RESUMO

Streptomyces phages WheeHeim and Forthebois are two novel members of the Tectiviridae family. These phages were isolated on cultures of the plant pathogen Streptomyces scabiei, known for its worldwide economic impact on potato crops. Transmission electron microscopy showed viral particles with double-layered icosahedral capsids, and frequent instances of protruding nanotubes harboring a collar-like structure. Mass-spectrometry confirmed the presence of lipids in the virion, and serial purification of colonies from turbid plaques and immunity testing revealed that both phages are temperate. Streptomyces phages WheeHeim and Forthebois have linear dsDNA chromosomes (18,266 bp and 18,251 bp long, respectively) with the characteristic two-segment architecture of the Tectiviridae. Both genomes encode homologs of the canonical tectiviral proteins (major capsid protein, packaging ATPase and DNA polymerase), as well as PRD1-type virion-associated transglycosylase and membrane DNA delivery proteins. Comparative genomics and phylogenetic analyses firmly establish that these two phages, together with Rhodococcus phage Toil, form a new genus within the Tectiviridae, which we have tentatively named Deltatectivirus. The identification of a cohesive clade of Actinobacteria-infecting tectiviruses with conserved genome structure but with scant sequence similarity to members of other tectiviral genera confirms that the Tectiviridae are an ancient lineage infecting a broad range of bacterial hosts.


Assuntos
Actinobacillus/virologia , Tectiviridae/classificação , Tectiviridae/fisiologia , Bacteriólise , Biologia Computacional/métodos , DNA Viral , Genoma Viral , Genômica/métodos , Especificidade de Hospedeiro , Anotação de Sequência Molecular , Filogenia , Streptomyces/virologia , Tectiviridae/isolamento & purificação , Tectiviridae/ultraestrutura
2.
Elife ; 82019 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-31513011

RESUMO

Bacteriophage PR772, a member of the Tectiviridae family, has a 70 nm diameter icosahedral protein capsid that encapsulates a lipid membrane, dsDNA, and various internal proteins. An icosahedrally averaged CryoEM reconstruction of the wild-type virion and a localized reconstruction of the vertex region reveal the composition and the structure of the vertex complex along with new protein conformations that play a vital role in maintaining the capsid architecture of the virion. The overall resolution of the virion is 2.75 Å, while the resolution of the protein capsid is 2.3 Å. The conventional penta-symmetron formed by the capsomeres is replaced by a large vertex complex in the pseudo T = 25 capsid. All the vertices contain the host-recognition protein, P5; two of these vertices show the presence of the receptor-binding protein, P2. The 3D structure of the vertex complex shows interactions with the viral membrane, indicating a possible mechanism for viral infection.


Assuntos
Bacteriófagos/ultraestrutura , Capsídeo/ultraestrutura , Microscopia Crioeletrônica , Tectiviridae/ultraestrutura , Proteínas do Capsídeo/ultraestrutura , Processamento de Imagem Assistida por Computador , Conformação Proteica
3.
Virol J ; 15(1): 67, 2018 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-29636073

RESUMO

BACKGROUND: Analysis of metagenomic sequences has become the principal approach for the study of the diversity of viruses. Many recent, extensive metagenomic studies on several classes of viruses have dramatically expanded the visible part of the virosphere, showing that previously undetected viruses, or those that have been considered rare, actually are important components of the global virome. RESULTS: We investigated the provenance of viruses related to tail-less bacteriophages of the family Tectiviridae by searching genomic and metagenomics sequence databases for distant homologs of the tectivirus-like Double Jelly-Roll major capsid proteins (DJR MCP). These searches resulted in the identification of numerous genomes of virus-like elements that are similar in size to tectiviruses (10-15 kilobases) and have diverse gene compositions. By comparison of the gene repertoires, the DJR MCP-encoding genomes were classified into 6 distinct groups that can be predicted to differ in reproduction strategies and host ranges. Only the DJR MCP gene that is present by design is shared by all these genomes, and most also encode a predicted DNA-packaging ATPase; the rest of the genes are present only in subgroups of this unexpectedly diverse collection of DJR MCP-encoding genomes. Only a minority encode a DNA polymerase which is a hallmark of the family Tectiviridae and the putative family "Autolykiviridae". Notably, one of the identified putative DJR MCP viruses encodes a homolog of Cas1 endonuclease, the integrase involved in CRISPR-Cas adaptation and integration of transposon-like elements called casposons. This is the first detected occurrence of Cas1 in a virus. Many of the identified elements are individual contigs flanked by inverted or direct repeats and appear to represent complete, extrachromosomal viral genomes, whereas others are flanked by bacterial genes and thus can be considered as proviruses. These contigs come from metagenomes of widely different environments, some dominated by archaea and others by bacteria, suggesting that collectively, the DJR MCP-encoding elements have a broad host range among prokaryotes. CONCLUSIONS: The findings reported here greatly expand the known host range of (putative) viruses of bacteria and archaea that encode a DJR MCP. They also demonstrate the extreme diversity of genome architectures in these viruses that encode no universal proteins other than the capsid protein that was used as the marker for their identification. From a supposedly minor group of bacterial and archaeal viruses, these viruses are emerging as a substantial component of the prokaryotic virome.


Assuntos
Vírus de Archaea/classificação , Vírus de Archaea/genética , Proteínas do Capsídeo/genética , Variação Genética , Genoma Viral/genética , Tectiviridae/classificação , Tectiviridae/genética , Archaea/virologia , Bactérias/virologia , Bases de Dados Genéticas , Genômica , Metagenômica , Filogenia
4.
Virology ; 518: 136-142, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29481984

RESUMO

Tectiviridae are composed of tailless bacteriophages with an icosahedral capsid and an inner membrane enclosing a double-stranded 15 kb linear DNA genome. Five of the seven previously studied Tectivirus isolates infect bacteria from Bacillus cereus sensu lato group (Betatectivirus), one distantly related member (PRD1) infect Enterobactericeae (Alpatectivirus) and one recently discovered virus infect Gluconobacter cerinus (Gammatectivirus). Here we expand the host spectrum of Betatectivirus elements to four additional genera (Streptococcus, Exiguobacterium, Clostridium and Brevibacillus) and to more distantly related Bacillus species (B. pumilus and B. flexus) by studying the genomes of fourteen novel tectiviral elements. Overall, the genomes show significant conservation in gene synteny and in modules responsible for genome replication and formation of the virion core (including DNA packaging). Notable variation exists in regions encoding host attachment and lysis along with the surrounding area of a site in which mutations are known to alter phage life cycle.


Assuntos
Bacillus/virologia , Bactérias Gram-Positivas/virologia , Tectiviridae/genética , Tectiviridae/fisiologia , DNA Viral/genética , Genoma Viral , Especificidade de Hospedeiro , Filogenia , Análise de Sequência de DNA
5.
Sci Rep ; 8(1): 1062, 2018 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-29348539

RESUMO

The oleaginous bacterium Rhodococcus opacus PD630 is metabolically diverse and can be cultivated on various renewable resources to serve as a sustainable triacylglycerol (TAG) feedstock for biodiesel production. Current methods for TAG extraction are costly, but infection of cultures by lytic bacteriophages (phages) may be a viable approach for achieving release of intracellular lipid from oleaginous bacteria such as R. opacus. This study reports the novel tectiviral phage Toil capable of releasing intracellular contents including a fluorescent protein marker and TAGs into the supernatant after phage infection of R. opacus PD631, a domesticated derivative of strain PD630. Phage Toil is placed in the Tectiviridae by its morphology, the presence of a lipid membrane, its genome architecture and the presence of terminal covalently-linked proteins. Toil is the first tectivirus capable of infecting a member of the Actinobacteria. Microscopy shows that infected cells do not undergo sudden lysis but instead maintain their original shape for several hours, with the cellular morphology gradually deteriorating. Approximately 30% of intracellular TAGs could be recovered from the culture supernatants of Toil-infected PD631 cells. Phage Toil has potential to be used as an agent in extraction of TAGs from oleaginous bacterium R. opacus. IMPORTANCE: This study reported the first tectivirus (Phage Toil) capable of infecting a member of the Actinobacteria. In this study, we showed that Phage Toil can infect oleaginous bacterium Rhodococcus opacus to release intracellular contents such as a fluorescent protein marker and TAG lipid granules, which can serve as a starting material for biodiesel production. This study demonstrates a new method to extract TAGs by using this phage. Additionally, Phage Toil can be a new model phage to advance knowledge regarding phage infection mechanisms in Rhodococcus and other mycolic acid-containing bacteria such as Mycobacterium.


Assuntos
Bactérias/metabolismo , Bactérias/virologia , Metabolismo dos Lipídeos , Lipídeos/química , Tectiviridae/fisiologia , Bacteriólise , Fracionamento Químico , Genoma Viral , Genômica/métodos , Tectiviridae/isolamento & purificação , Tectiviridae/ultraestrutura , Replicação Viral
6.
Viruses ; 10(1)2018 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-29337868

RESUMO

The Gluconobacter phage GC1 is a novel member of the Tectiviridae family isolated from a juice sample collected during dry white wine making. The bacteriophage infects Gluconobacter cerinus, an acetic acid bacterium which represents a spoilage microorganism during wine making, mainly because it is able to produce ethyl alcohol and transform it into acetic acid. Transmission electron microscopy revealed tail-less icosahedral particles with a diameter of ~78 nm. The linear double-stranded DNA genome of GC1 (16,523 base pairs) contains terminal inverted repeats and carries 36 open reading frames, only a handful of which could be functionally annotated. These encode for the key proteins involved in DNA replication (protein-primed family B DNA polymerase) as well as in virion structure and assembly (major capsid protein, genome packaging ATPase (adenosine triphosphatase) and several minor capsid proteins). GC1 is the first tectivirus infecting an alphaproteobacterial host and is thus far the only temperate tectivirus of gram-negative bacteria. Based on distinctive sequence and life-style features, we propose that GC1 represents a new genus within the Tectiviridae, which we tentatively named "Gammatectivirus". Furthermore, GC1 helps to bridge the gap in the sequence space between alphatectiviruses and betatectiviruses.


Assuntos
Ácido Acético/metabolismo , Gluconobacter/virologia , Tectiviridae/classificação , Vinho/microbiologia , Replicação do DNA , DNA Viral/genética , Genoma Viral , Gluconobacter/metabolismo , Fases de Leitura Aberta , Filogenia , Análise de Sequência de DNA , Tectiviridae/genética , Tectiviridae/isolamento & purificação , Vírion/genética
7.
Nucleic Acids Res ; 44(20): 9733-9744, 2016 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-27466389

RESUMO

Protein-primed replication constitutes a generalized mechanism to initiate DNA or RNA synthesis in a number of linear genomes of viruses, linear plasmids and mobile elements. By this mechanism, a so-called terminal protein (TP) primes replication and becomes covalently linked to the genome ends. Bam35 belongs to a group of temperate tectiviruses infecting Gram-positive bacteria, predicted to replicate their genomes by a protein-primed mechanism. Here, we characterize Bam35 replication as an alternative model of protein-priming DNA replication. First, we analyze the role of the protein encoded by the ORF4 as the TP and characterize the replication mechanism of the viral genome (TP-DNA). Indeed, full-length Bam35 TP-DNA can be replicated using only the viral TP and DNA polymerase. We also show that DNA replication priming entails the TP deoxythymidylation at conserved tyrosine 194 and that this reaction is directed by the third base of the template strand. We have also identified the TP tyrosine 172 as an essential residue for the interaction with the viral DNA polymerase. Furthermore, the genetic information of the first nucleotides of the genome can be recovered by a novel single-nucleotide jumping-back mechanism. Given the similarities between genome inverted terminal repeats and the genes encoding the replication proteins, we propose that related tectivirus genomes can be replicated by a similar mechanism.


Assuntos
Replicação do DNA , DNA Viral , Genoma Viral , Tectiviridae/fisiologia , Proteínas Virais/metabolismo , Sequência de Aminoácidos , Fagos Bacilares/fisiologia , Sequência de Bases , Sítios de Ligação , Fases de Leitura Aberta/genética , Ligação Proteica , Proteínas Virais/química
8.
Appl Environ Microbiol ; 80(24): 7620-30, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25261525

RESUMO

Bacillus thuringiensis is an entomopathogenic bacterium that has been used as an efficient biopesticide worldwide. Despite the fact that this bacterium is usually described as an insect pathogen, its life cycle in the environment is still largely unknown. B. thuringiensis belongs to the Bacillus cereus group of bacteria, which has been associated with many mobile genetic elements, such as species-specific temperate or virulent bacteriophages (phages). Temperate (lysogenic) phages are able to establish a long-term relationship with their host, providing, in some cases, novel ecological traits to the bacterial lysogens. Therefore, this work focuses on evaluating the potential influence of temperate tectiviruses GIL01 and GIL16 on the development of different life traits of B. thuringiensis. For this purpose, a B. thuringiensis serovar israelensis plasmid-cured (nonlysogenic) strain was used to establish bacterial lysogens for phages GIL01 and GIL16, and, subsequently, the following life traits were compared among the strains: kinetics of growth, metabolic profiles, antibiotics susceptibility, biofilm formation, swarming motility, and sporulation. The results revealed that GIL01 and GIL16 lysogeny has a significant influence on the bacterial growth, sporulation rate, biofilm formation, and swarming motility of B. thuringiensis. No changes in metabolic profiles or antibiotic susceptibilities were detected. These findings provide evidence that tectiviruses have a putative role in the B. thuringiensis life cycle as adapters of life traits with ecological advantages.


Assuntos
Bacillus thuringiensis/fisiologia , Bacteriófagos/fisiologia , Biofilmes , Lisogenia , Tectiviridae/fisiologia , Bacillus thuringiensis/genética , Bacillus thuringiensis/crescimento & desenvolvimento , Bacillus thuringiensis/virologia , Esporos Bacterianos/genética , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Bacterianos/fisiologia , Esporos Bacterianos/virologia
9.
Appl Environ Microbiol ; 80(14): 4138-52, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24795369

RESUMO

GIL01, Bam35, GIL16, AP50, and Wip1 are tectiviruses preying on the Bacillus cereus group. Despite the significant contributions of phages in different biological processes, little is known about the dealings taking place between tectiviruses and their Gram-positive bacterial hosts. Therefore, this work focuses on characterizing the interactions between tectiviruses and the B. cereus group by assessing their occurrence and genetic diversity and evaluating their host range. To study the occurrence of tectiviruses in the B. cereus group, 2,000 isolates were evaluated using primers designed to be specific to two variable regions detected in previously described elements. PCR and propagation tests revealed that tectivirus-like elements occurred in less than 3% of the isolates. Regardless of this limited distribution, several novel tectiviruses were found, and partial DNA sequencing indicated that a greater diversity exists within the family Tectiviridae. Analyses of the selected variable regions, along with their host range, showed that tectiviruses in the B. cereus group can be clustered mainly into two different groups: the ones infecting B. anthracis and those isolated from other B. cereus group members. In order to address the host range of some novel tectiviruses, 120 strains were tested for sensitivity. The results showed that all the tested tectiviruses produced lysis in at least one B. cereus sensu lato strain. Moreover, no simple relationship between the infection patterns of the tectiviruses and their diversity was found.


Assuntos
Bacillus cereus/virologia , Especificidade de Hospedeiro/genética , Tectiviridae/classificação , Bacillus cereus/classificação , Meios de Cultura/química , Primers do DNA , DNA Bacteriano/genética , DNA Viral/genética , Genes Bacterianos , Genes Virais , Variação Genética , Alinhamento de Sequência , Análise de Sequência de DNA , Tectiviridae/genética , Tectiviridae/isolamento & purificação
10.
J Bacteriol ; 195(19): 4355-64, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23893110

RESUMO

Tectiviridae is a family of tailless bacteriophages with Gram-negative and Gram-positive hosts. The family model PRD1 and its close relatives all infect a broad range of enterobacteria by recognizing a plasmid-encoded conjugal transfer complex as a receptor. In contrast, tectiviruses with Gram-positive hosts are highly specific to only a few hosts within the same bacterial species. The cellular determinants that account for the observed specificity remain unknown. Here we present the genome sequence of Wip1, a tectivirus that infects the pathogen Bacillus anthracis. The Wip1 genome is related to other tectiviruses with Gram-positive hosts, notably, AP50, but displays some interesting differences in its genome organization. We identified Wip1 candidate genes for the viral spike complex, the structure located at the capsid vertices and involved in host receptor binding. Phage adsorption and inhibition tests were combined with immunofluorescence microscopy to show that the Wip1 gene product p23 is a receptor binding protein. His-p23 also formed a stable complex with p24, a Wip1 protein of unknown function, suggesting that the latter is involved with p23 in host cell recognition. The narrow host range of phage Wip1 and the identification of p23 as a receptor binding protein offer a new range of suitable tools for the rapid identification of B. anthracis.


Assuntos
Bacillus anthracis/metabolismo , Receptores Virais/fisiologia , Tectiviridae/fisiologia , Bacillus anthracis/citologia , Clonagem Molecular , DNA Viral/genética , Regulação Bacteriana da Expressão Gênica , Regulação Viral da Expressão Gênica , Genoma Viral , Ligantes , Microscopia de Fluorescência , Dados de Sequência Molecular , Receptores Virais/genética , Especificidade da Espécie
11.
Res Microbiol ; 164(2): 118-26, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23103336

RESUMO

Our biosphere is abundant with unique and small genes for which no homologs are known. These genes, often referred to as orphans or ORFans, are commonly found in bacteriophage genomes but their origins remain unclear. We discovered five novel tectivirus-like genetic elements by screening more than five-hundred Bacillus strains. A highly variable region (HVR) of these viruses was shown to harbor ORFans in most of these otherwise well-conserved bacteriophages. Previous studies demonstrated that mutations close to this region dramatically alter bacteriophage gene regulation, suggesting that the acquisition of those ORFans may provide a source of genetic diversity that is then subject to genetic selection during bacteriophage evolution.


Assuntos
Fagos Bacilares/classificação , Fagos Bacilares/isolamento & purificação , Bacillus/virologia , Variação Genética , Tectiviridae/classificação , Tectiviridae/isolamento & purificação , Sequência de Aminoácidos , DNA Viral/química , DNA Viral/genética , Microscopia Eletrônica de Transmissão , Dados de Sequência Molecular , Alinhamento de Sequência , Análise de Sequência de DNA , Vírion/ultraestrutura
12.
Appl Environ Microbiol ; 74(21): 6792-6, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18791014

RESUMO

The genome sequence of a Bacillus anthracis-specific clear plaque mutant phage, AP50c, contains 31 open reading frames spanning 14,398 bp, has two mutations compared to wild-type AP50t, and has a colinear genome architecture highly similar to that of gram-positive Tectiviridae phages. Spontaneous AP50c-resistant B. anthracis mutants exhibit a mucoid colony phenotype.


Assuntos
Fagos Bacilares/genética , Bacillus anthracis/virologia , DNA Viral/genética , Genoma Viral , Bacteriólise , Sequência de Bases , Ordem dos Genes , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Mutação Puntual , Análise de Sequência de DNA , Sintenia , Tectiviridae/genética , Ensaio de Placa Viral , Vírion/ultraestrutura
13.
Virology ; 379(1): 10-9, 2008 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-18657283

RESUMO

Icosahedral dsDNA viruses isolated from hot springs and proposed to belong to the Tectiviridae family infect the gram-negative thermophilic Thermus thermophilus bacterium. Seven such viruses were obtained from the Promega Corporation collection. The structural protein patterns of three of these viruses, growing to a high titer, appeared very similar but not identical. The most stable virus, P23-77, was chosen for more detailed studies. Analysis of highly purified P23-77 by thin layer chromatography for neutral lipids showed lipid association with the virion. Cryo-EM based three-dimensional image reconstruction of P23-77 to 1.4 nm resolution revealed an icosahedrally-ordered protein coat, with spikes on the vertices, and an internal membrane. The capsid architecture of P23-77 is most similar to that of the archaeal virus SH1. These findings further complicate the grouping of icosahedrally-symmetric viruses containing an inner membrane. We propose a single superfamily or order with members in several viral families.


Assuntos
Bacteriófagos/química , Bacteriófagos/ultraestrutura , Tectiviridae/química , Tectiviridae/ultraestrutura , Thermus thermophilus/virologia , Bacteriófagos/classificação , Bacteriófagos/isolamento & purificação , Microscopia Crioeletrônica , Fontes Termais/virologia , Lipídeos/análise , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína , Tectiviridae/classificação , Tectiviridae/isolamento & purificação , Ensaio de Placa Viral , Proteínas Estruturais Virais/isolamento & purificação , Vírion/química , Vírion/ultraestrutura
14.
Methods Mol Biol ; 394: 213-34, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-18363238

RESUMO

Out of 177 surveyed bacteriophages, 161 (91%) are tailed and belong to the Myoviridae, Siphoviridae, and Podoviridae families (43, 55, and 59 viruses, respectively). Sixteen filamentous or isometric phages are members of the Inoviridae, Leviviridae, Microviridae, and Tectiviridae families (9%). Many tailed phages belong to established phage genera (P22, T1, T5, and T7), which are widespread in enterobacteria and other Gram-negatives of the Proteobacteria phylum.


Assuntos
Fagos de Salmonella/ultraestrutura , Salmonella/virologia , Bacteriófago P22/ultraestrutura , Tipagem de Bacteriófagos , Inoviridae/classificação , Inoviridae/ultraestrutura , Leviviridae/classificação , Leviviridae/ultraestrutura , Microscopia Eletrônica de Transmissão , Microviridae/classificação , Microviridae/ultraestrutura , Myoviridae/classificação , Myoviridae/ultraestrutura , Podoviridae/classificação , Podoviridae/ultraestrutura , Fagos de Salmonella/classificação , Siphoviridae/classificação , Siphoviridae/ultraestrutura , Tectiviridae/classificação , Tectiviridae/ultraestrutura
16.
Structure ; 13(12): 1819-28, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16338410

RESUMO

Biological membranes control the flow of molecules into and out of cells, and they transmit information about the milieu. Structural studies of membrane-containing viruses provide one way to study these membranes in situ. Cryo-electron microscopy and image reconstruction of bacteriophage Bam35 to 7.3 A resolution revealed a membrane bilayer constrained within an icosahedrally symmetric pseudo T = 25 capsid. A total of 60 large transmembrane protein complexes affect the curvature and thickness of the membrane. Here, we describe these membrane parameters quantitatively. Furthermore, we show that Bam35 differs from bacteriophage PRD1 in these parameters, even though the two viruses share the same principles of capsid architecture. Most notably, each virus possesses a tape measure protein suggesting a general mechanism for capsid size determination in icosahedral viruses.


Assuntos
Bacillus thuringiensis/virologia , Capsídeo/ultraestrutura , Proteínas de Membrana/ultraestrutura , Tectiviridae/ultraestrutura , Proteínas Virais/ultraestrutura , Bacteriófago PRD1/fisiologia , Bacteriófago PRD1/ultraestrutura , Microscopia Crioeletrônica , Bicamadas Lipídicas/química , Membranas/ultraestrutura , Tectiviridae/fisiologia
17.
J Mol Biol ; 350(3): 427-40, 2005 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-15946683

RESUMO

The origin, evolution and relationships of viruses are all fascinating topics. Current thinking in these areas is strongly influenced by the tailed double-stranded (ds) DNA bacteriophages. These viruses have mosaic genomes produced by genetic exchange and so new natural isolates are quite dissimilar to each other, and to laboratory strains. Consequently, they are not amenable to study by current tools for phylogenetic analysis. Less attention has been paid to the Tectiviridae family, which embraces icosahedral dsDNA bacterial viruses with an internal lipid membrane. It includes viruses, such as PRD1, that infect Gram-negative bacteria, as well as viruses like Bam35 with Gram-positive hosts. Although PRD1 and Bam35 have closely related virion morphology and genome organization, they have no detectable sequence similarity. There is strong evidence that the Bam35 coat protein has the "double-barrel trimer" arrangement of PRD1 that was first observed in adenovirus and is predicted to occur in other viruses with large facets. It is very likely that a single ancestral virus gave rise to this very large group of viruses. The unprecedented degree of conservation recently observed for two Bam35-like tectiviruses made it important to investigate those infecting Gram-negative bacteria. The DNA sequences for six PRD1-like isolates (PRD1, PR3, PR4, PR5, L17, PR772) have now been determined. Remarkably, these bacteriophages, isolated at distinctly different dates and global locations, have almost identical genomes. The discovery of almost invariant genomes for the two main Tectiviridae groups contrasts sharply with the situation in the tailed dsDNA bacteriophages. Notably, it permits a sequence analysis of the isolates revealing that the tectiviral proteins can be dissected into a slowly evolving group descended from the ancestor, the viral self, and a more rapidly changing group reflecting interactions with the host.


Assuntos
Genoma Viral , Tectiviridae/genética , Sequência de Aminoácidos , Bacteriófago PRD1/genética , Bacteriófagos/metabolismo , Sequência de Bases , Membrana Celular/metabolismo , Biologia Computacional , Cristalografia por Raios X , DNA/química , DNA/genética , DNA de Cadeia Simples/metabolismo , DNA Viral/metabolismo , Bases de Dados de Proteínas , Escherichia coli/metabolismo , Evolução Molecular , Teste de Complementação Genética , Lipídeos/química , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Conformação de Ácido Nucleico , Fases de Leitura Aberta , Óperon , Filogenia , Plasmídeos/metabolismo , Ligação Proteica , Estrutura Secundária de Proteína , Homologia de Sequência do Ácido Nucleico , Software
18.
J Bacteriol ; 187(6): 1966-73, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15743944

RESUMO

One of the most notable characteristics of Tectiviridae resides in their double-layer coats: the double-stranded DNA is located within a flexible lipoprotein vesicle covered by a rigid protein capsid. Despite their apparent rarity, tectiviruses have an extremely wide distribution compared to other phage groups. Members of this family have been found to infect gram-negative (PRD1 and relatives) as well as gram-positive (Bam35, GIL01, AP50, and phiNS11) hosts. Several reports have shown that tectiviruses infecting gram-negative bacteria are closely related, whereas no information is currently available on the genetic relationship among those infecting gram-positive bacteria. The present study reports the sequence of GIL16, a new isolate originating from Bacillus thuringiensis, and a genetic comparison of this isolate with the tectiviral bacteriophages Bam35 and GIL01, which originated from B. thuringiensis serovars Alesti and Israelensis, respectively. In contrast to PRD1 and its relatives, these are temperate bacteriophages existing as autonomous linear prophages within the host cell. Mutations in a particular motif in both the GIL01 and GIL16 phages are also shown to correlate with a switch to the lytic cycle. Interestingly, both bacterial viruses displayed narrow, yet slightly different, host spectrums. We also explore the hypothesis that pBClin15, a linear plasmid hosted by the Bacillus cereus reference strain ATCC 14579, is also a prophage. Sequencing of its inverted repeats at both extremities and a comparison with GIL01 and GIL16 emphasize its relationship to the Tectiviridae.


Assuntos
Bacillus cereus/virologia , Bacillus thuringiensis/virologia , Genes Virais , Tectiviridae/classificação , Tectiviridae/genética , Sequência de Bases , Genoma Viral , Microscopia Eletrônica , Dados de Sequência Molecular , Plasmídeos , Prófagos/classificação , Prófagos/genética , Prófagos/ultraestrutura , Tectiviridae/ultraestrutura
19.
Lett Appl Microbiol ; 38(4): 333-8, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15214735

RESUMO

AIM: To isolate bacterial viruses that infect the ruminal cellulolytic bacterium Ruminococcus albus. METHODS: Four phages infecting R. albus AR67 were isolated under anaerobic conditions using the soft-agar overlay technique. The phages were characterized on morphology, solvent stability, nucleic acid type and digestion characteristics. Two phages, phiRa02 and phiRa04 comprised icosahedral virions with linear double-stranded DNA and appeared to belong to the family Podoviridae [corrected] The other two phages are most likely filamentous phages with circular single-stranded DNA of the family Inoviridae. SIGNIFICANCE OF THE STUDY: Viruses of the family Inoviridae [corrected] have not previously been isolated from rumen bacteria. The phages isolated in this study are the first phages shown to infect the cellulolytic bacteria of the rumen. This suggests that the cellulolytic populations of the rumen are subject to lytic events that may impact on the ability of these bacteria to degrade plant fibre and on the nutrition of the animal.


Assuntos
Inoviridae/isolamento & purificação , Inovirus/isolamento & purificação , Ruminococcus/virologia , Tectiviridae/isolamento & purificação , Anaerobiose , DNA/isolamento & purificação , DNA/metabolismo , Impressões Digitais de DNA , Enzimas de Restrição do DNA/metabolismo , DNA Circular/isolamento & purificação , DNA Circular/metabolismo , DNA de Cadeia Simples/isolamento & purificação , DNA de Cadeia Simples/metabolismo , DNA Viral/isolamento & purificação , DNA Viral/metabolismo , Inoviridae/classificação , Inoviridae/fisiologia , Inoviridae/ultraestrutura , Inovirus/classificação , Inovirus/fisiologia , Inovirus/ultraestrutura , Nucleocapsídeo/ultraestrutura , Tectiviridae/classificação , Tectiviridae/fisiologia , Tectiviridae/ultraestrutura
20.
Virology ; 322(2): 328-36, 2004 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-15110530

RESUMO

The phospholipid (PL) molecular species compositions of bacteriophages PRD1 and Bam35 as well as their respective hosts were determined quantitatively using liquid chromatography/electrospray ionization mass-spectrometry (LC-ESI-MS) and backed up by gas-chromatographic/mass-spectrometric (GC-MS) analysis of the total fatty acids (FAs). The results showed that both viruses contain significantly more phosphatidylglycerol (PG) and less phosphatidylethanolamine (PE) than the host membranes. Only modest differences in the molecular species composition of the viruses and their respective hosts were observed, indicating that the virus assembly process is relatively nonselective in respect of the fatty acid (FA) proportion of phospholipids (PL). These data indicate that the PL composition of these two viruses is largely, albeit not exclusively, determined by the availability of phospholipids in the host membrane.


Assuntos
Bacillus thuringiensis/química , Bacteriófago PRD1/química , Fosfolipídeos/análise , Salmonella enterica/química , Tectiviridae/química , Fagos Bacilares/química , Bacillus thuringiensis/virologia , Cromatografia Líquida , Ácidos Graxos/análise , Salmonella enterica/virologia , Espectrometria de Massas por Ionização por Electrospray
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