Genome analysis of deep-sea thermophilic phage D6E

Bacteriophages and bacterial extracellular vesicles, threat or opportunity?

Emergence of antimicrobial-resistant bacteria (AMR) is one of the health major problems worldwide. The scientists are looking for a novel method to treat infectious diseases. Phage therapy is considered a suitable approach for treating infectious diseases. However, there are different challenges in this way. Some biological aspects can probably influence on therapeutic results and further investigations are necessary to reach a successful phage therapy. Bacteriophage activity can influence by bacterial defense system. Bacterial extracellular vesicles (BEVs) are one of the bacterial defense mechanisms which can modify the results of bacteriophage activity. BEVs have the significant roles in the gene transferring, invasion, escape, and spreading of bacteriophages. In this review, the defense mechanisms of bacteria against bacteriophages, especially BEVs secretion, the hidden linkage of BEVs and bacteriophages, and its possible consequences on the bacteriophage activity as well phage therapy will be discussed.

Bacteriophages of Thermophilic 'Bacillus Group' Bacteria-A Systematic Review, 2023 Update

Bacteriophages associated with thermophiles are gaining increased attention due to their pivotal roles in various biogeochemical and ecological processes, as well as their applications in biotechnology and bionanotechnology. Although thermophages are not suitable for controlling bacterial infections in humans or animals, their individual components, such as enzymes and capsid proteins, can be employed in molecular biology and significantly contribute to the enhancement of human and animal health. Despite their significance, thermophages still remain underrepresented in the known prokaryotic virosphere, primarily due to limited in-depth investigations. However, due to their unique properties, thermophages are currently attracting increasing interest, as evidenced by several newly discovered phages belonging to this group. This review offers an updated compilation of thermophages characterized to date, focusing on species infecting the thermophilic bacilli. Moreover, it presents experimental findings, including novel proteomic data (39 proteins) concerning the model TP-84 bacteriophage, along with the first announcement of 6 recently discovered thermophages infecting Geobacillus thermodenitrificans: PK5.2, PK2.1, NIIg10.1, NIIg2.1, NIIg2.2, and NIIg2.3. This review serves as an update to our previous publication in 2021.

Geobacillus Bacteriophages from Compost Heaps: Representatives of Three New Genera within Thermophilic Siphoviruses

We report a detailed characterization of five thermophilic bacteriophages (phages) that were isolated from compost heaps in Vilnius, Lithuania using Geobacillus thermodenitrificans strains as the hosts for phage propagation. The efficiency of plating experiments revealed that phages formed plaques from 45 to 80 °C. Furthermore, most of the phages formed plaques surrounded by halo zones, indicating the presence of phage-encoded bacterial exopolysaccharide (EPS)-degrading depolymerases. Transmission Electron Microscopy (TEM) analysis revealed that all phages were siphoviruses characterized by an isometric head (from ~63 nm to ~67 nm in diameter) and a non-contractile flexible tail (from ~137 nm to ~150 nm in length). The genome sequencing resulted in genomes ranging from 38,161 to 39,016 bp. Comparative genomic and phylogenetic analysis revealed that all the isolated phages had no close relatives to date, and potentially represent three new genera within siphoviruses. The results of this study not only improve our knowledge about poorly explored thermophilic bacteriophages but also give new insights for further investigation of thermophilic and/or thermostable enzymes of bacterial viruses.

Isolation and Characterization of the First Temperate Virus Infecting Psychrobacillus from Marine Sediments

Viruses are far more abundant than cellular microorganisms in the marine ecosystem. However, very few viruses have so far been isolated from marine sediments, especially hydrothermal vent sediments, hindering the understanding of the biology and ecological functions of these tiny organisms. Here, we report the isolation and characterization of a temperate bacteriophage, named PVJ1, which infects Psychrobacillus from a hydrothermal vent field in Okinawa Trough. PVJ1 belongs to the Myoviridae family of the order Caudovirales. The tailed phage possesses a 53,187 bp linear dsDNA genome, with 84 ORFs encoding structural proteins, genome replication, host lysis, etc. in a modular pattern. The phage genome is integrated into the host chromosome near the 3′-end of deoD, a gene encoding purine nucleoside phosphorylase (PNP). The phage integration does not appear to disrupt the function of PNP. The phage DNA is packaged by the headful mechanism. Release of PVJ1 from the host cell was drastically enhanced by treatment with mitomycin C. Phages encoding an MCP sharing significant similarity (≥70% identical amino acids) with that of PVJ1 are widespread in diverse environments, including marine and freshwater sediments, soils, artificial ecosystems, and animal intestines, and primarily infect Firmicutes. These results are valuable to the understanding of the lifestyle and host interactions of bacterial viruses at the bottom of the ocean.

Wastewater as a fertility source for novel bacteriophages against multi-drug resistant bacteria

Antibiotic resistance is a common and serious public health worldwide. As an alternative to antibiotics, bacteriophage (phage) therapy offers one of the best solutions to antibiotic resistance. Bacteriophages survive where their bacterial hosts are found; thus, they exist in almost all environments and their applications are quite varied in the medical, environmental, and industrial fields. Moreover, a single phage or a mixture of phages can be used in phage therapy; mixed phages tend to be more effective in reducing the number and/or activity of pathogenic bacteria than that of a single phage.

Bacteriophages of Thermophilic 'Bacillus Group' Bacteria-A Review

Bacteriophages of thermophiles are of increasing interest owing to their important roles in many biogeochemical, ecological processes and in biotechnology applications, including emerging bionanotechnology. However, due to lack of in-depth investigation, they are underrepresented in the known prokaryotic virosphere. Therefore, there is a considerable potential for the discovery of novel bacteriophage-host systems in various environments: marine and terrestrial hot springs, compost piles, soil, industrial hot waters, among others. This review aims at providing a reference compendium of thermophages characterized thus far, which infect the species of thermophilic 'Bacillus group' bacteria, mostly from Geobacillus sp. We have listed 56 thermophages, out of which the majority belong to the Siphoviridae family, others belong to the Myoviridae and Podoviridae families and, apparently, a few belong to the Sphaerolipoviridae, Tectiviridae or Corticoviridae families. All of their genomes are composed of dsDNA, either linear, circular or circularly permuted. Fourteen genomes have been sequenced; their sizes vary greatly from 35,055 bp to an exceptionally large genome of 160,590 bp. We have also included our unpublished data on TP-84, which infects Geobacillus stearothermophilus (G. stearothermophilus). Since the TP-84 genome sequence shows essentially no similarity to any previously characterized bacteriophage, we have defined TP-84 as a new species in the newly proposed genus Tp84virus within the Siphoviridae family. The information summary presented here may be helpful in comparative deciphering of the molecular basis of the thermophages' biology, biotechnology and in analyzing the environmental aspects of the thermophages' effect on the thermophile community.

vB_BcM_Sam46 and vB_BcM_Sam112, members of a new bacteriophage genus with unusual small terminase structure

One of the serious public health concerns is food contaminated with pathogens and their vital activity products such as toxins. Bacillus cereus group of bacteria includes well-known pathogenic species such as B. anthracis, B. cereus sensu stricto (ss), B. cytotoxicus and B. thuringiensis. In this report, we describe the Bacillus phages vB_BcM_Sam46 and vB_BcM_Sam112 infecting species of this group. Electron microscopic analyses indicated that phages Sam46 and Sam112 have the myovirus morphotype. The genomes of Sam46 and Sam112 comprise double-stranded DNA of 45,419 bp and 45,037 bp in length, respectively, and have the same GC-content. The genome identity of Sam46 and Sam112 is 96.0%, indicating that they belong to the same phage species. According to the phylogenetic analysis, these phages form a distinct clade and may be members of a new phage genus, for which we propose the name 'Samaravirus'. In addition, an interesting feature of the Sam46 and Sam112 phages is the unusual structure of their small terminase subunit containing N-terminal FtsK_gamma domain.

Viruses in Extreme Environments, Current Overview, and Biotechnological Potential

Virus research has advanced significantly since the discovery of the tobacco mosaic virus (TMV), the characterization of its infection mechanisms and the factors that determine their pathogenicity. However, most viral research has focused on pathogenic viruses to humans, animals and plants, which represent only a small fraction in the virosphere. As a result, the role of most viral genes, and the mechanisms of coevolution between mutualistic viruses, their host and their environment, beyond pathogenicity, remain poorly understood. This review focuses on general aspects of viruses that interact with extremophile organisms, characteristics and examples of mechanisms of adaptation. Finally, this review provides an overview on how knowledge of extremophile viruses sheds light on the application of new tools of relevant use in modern molecular biology, discussing their value in a biotechnological context.

Structural and functional characterization of the deep-sea thermophilic bacteriophage GVE2 tailspike protein

The genome of the thermophilic bacteriophage GVE2 encodes a putative tailspike protein (GVE2 TSP). Here we report the crystal structure of the truncated GVE2 TSP at 2.0-Å resolution lacking 204 amino acid residues at its N-terminus (ΔnGVE2 TSP), possessing a "vase" outline similar to other TSP's structures. However, ΔnGVE2 TSP displays structural characteristics distinct from other TSPs. Despite lacking 204 amino acid residues, the head domain forms an asymmetric trimer compared to symmetric in other TSPs, suggesting that its long N-terminus may be unique to the long-tailed bacteriophages. Furthermore, the α-helix of the neck is 5-7 amino acids longer than that of other TSPs. The most striking feature is that its binding domain consists of a β-helix with 10 turns, whereas other TSPs have 13 turns, even including the phage Sf6 TSP, which is the closest homologue of GVE2 TSP. The C-terminal structure is also quite different with those of other TSPs. Furthermore, we observed that ΔnGVE2 TSP can slow down growth of its host, demonstrating that this TSP is essential for the phage GVE2 to infect its host. Overall, the structural characteristics suggest that GVE2 TSP may be more primitive than other phage TSPs.

A novel thermophilic Aeribacillus bacteriophage AP45 isolated from the Valley of Geysers, Kamchatka: genome analysis suggests the existence of a new genus within the Siphoviridae family

A novel thermophilic bacteriophage AP45 and its host strain Aeribacillus sp. CEMTC656 were isolated from the Valley of Geysers, Kamchatka Peninsula, Russia. Bacteriophage AP45 was identified as a member of the Siphoviridae family by electron microscopy. It showed high thermostability and had a slow cycle of reproduction. The AP45 genome had 51,606 base pairs (bp) and contained 71 open reading frames (ORFs), 40 of them encoding proteins of predicted function. Genes encoding DNA and RNA polymerases were not identified, indicating that AP45 used host polymerases. Based on the ORF65 encoding putative endolysin, the recombinant protein rAP45Lys was developed and its peptidoglycan-hydrolyzing activity was demonstrated. The AP45 genome exhibited limited identity to other phage sequences; the highest identity, 36%, was with the genome of the thermophilic Geobacillus myovirus D6E. The majority of putative proteins encoded by the AP45 genome had higher similarity to proteins from bacteria belonging to the Bacillaceae family, than to bacteriophages. In addition, more than half of the putative ORFs in the AP45 genome were highly similar to prophage sequences of A. pallidus strain 8m3, which was isolated in north-east China. The AP45 phage and revealed prophages might be members of a new genus belonging to the Siphoviridae family.

Sequence, genome organization, annotation and proteomics of the thermophilic, 47.7-kb Geobacillus stearothermophilus bacteriophage TP-84 and its classification in the new Tp84virus genus

Bacteriophage TP-84 is a well-characterized bacteriophage of historical interest. It is a member of the Siphoviridae, and infects a number of thermophilic Geobacillus (Bacillus) stearothermophilus strains. Its’ 47.7-kbp double-stranded DNA genome revealed the presence of 81 coding sequences (CDSs) coding for polypeptides of 4 kDa or larger. Interestingly, all CDSs are oriented in the same direction, pointing to a dominant transcription direction of one DNA strand. Based on a homology search, a hypothetical function could be assigned to 31 CDSs. No RNA or DNA polymerase-coding genes were found on the bacteriophage genome indicating that TP-84 relies on the host’s transcriptional and replication enzymes. The TP84 genome is tightly packed with CDSs, typically spaced by several-to-tens of bp or often overlapping. The genome contains five putative promoter-like sequences showing similarity to the host promoter consensus sequence and allowing for a 2-bp mismatch. In addition, ten putative rho-independent terminators were detected. Because the genome sequence shows essentially no similarity to any previously characterised bacteriophage, TP-84 should be considered a new species in an undefined genus within the Siphoviridae family. Thus a taxonomic proposal of a new Tp84virus genus has been accepted by the International Committee on Taxonomy of Viruses. The bioinformatics genome analysis was verified by confirmation of 33 TP-84 proteins, which included: a) cloning of a selected CDS in Escherichia coli, coding for a DNA single-stranded binding protein (SSB; gene TP84_63), b) purification and functional assays of the recombinant TP-84 SSB, which has been shown to improve PCR reactions, c) mass spectrometric (MS) analysis of TP-84 bacteriophage capsid proteins, d) purification of TP-84 endolysin activity, e) MS analysis of the host cells from infection time course.

Description of a cryptic thermophilic (pro)phage, CBP1 from Caldibacillus debilis strain GB1

This study characterizes a cryptic (pro)phage-related sequence within the Caldibacillus debilis GB1 genome, designated CBP1.CBP1 is a Siphoviridae-like genome highly related to GBVS1 from Geobacillus sp. 6k51. The CBP1genome is a 37,315 bp region containing 69 putative ORFs with a GC content of 42% flanked on both sides by host DNA integrated into the main bacterial chromosome (contig 16). Bioinformatic analyses identified cassettes of genes within the CBP1 genome that were similar in function, yet distinct in sequence, from genes previously identified in GBVS1. All of CBP1 genes had less than 60% amino acid sequence identity with GBVS1by tBLASTx, with the exception of the TMP repeat gene. CBP1 possessed all the necessary genes to undergo a temperate/lytic phage life cycle, including excision, replication, structural genes, DNA packaging, and cell lyses. Proteomic analysis of CBP1 revealed the expression of 5 proteins. One of the expressed proteins was a transcriptional regulator protein homologous to the bacteriophage λ repressor protein (cI) expressed in high amounts from the CBP1 region, consistent with a lysogenic phage in a repressed state. The CBP1 protein expression profile during host growth provides unique insight into thermophilic Siphoviridae-like phages in the repressed state within their host cells.

Structure of the large terminase from a hyperthermophilic virus reveals a unique mechanism for oligomerization and ATP hydrolysis

The crystal structure of the large terminase from the Geobacillus stearothermophilus bacteriophage D6E shows a unique relative orientation of the N-terminal adenosine triphosphatase (ATPase) and C-terminal nuclease domains. This monomeric ‘initiation’ state with the two domains ‘locked’ together is stabilized via a conserved C-terminal arm, which may interact with the portal protein during motor assembly, as predicted for several bacteriophages. Further work supports the formation of an active oligomeric state: (i) AUC data demonstrate the presence of oligomers; (ii) mutational analysis reveals a trans-arginine finger, R158, indispensable for ATP hydrolysis; (iii) the location of this arginine is conserved with the HerA/FtsK ATPase superfamily; (iv) a molecular docking model of the pentamer is compatible with the location of the identified arginine finger. However, this pentameric model is structurally incompatible with the monomeric ‘initiation’ state and is supported by the observed increase in k_cat of ATP hydrolysis, from 7.8 ± 0.1 min⁻¹ to 457.7 ± 9.2 min⁻¹ upon removal of the C-terminal nuclease domain. Taken together, these structural, biophysical and biochemical data suggest a model where transition from the ‘initiation’ state into a catalytically competent pentameric state, is accompanied by substantial domain rearrangements, triggered by the removal of the C-terminal arm from the ATPase active site.

Deep-Sea Hydrothermal Vent Viruses Compensate for Microbial Metabolism in Virus-Host Interactions

Viruses are believed to be responsible for the mortality of host organisms. However, some recent investigations reveal that viruses may be essential for host survival. To date, it remains unclear whether viruses are beneficial or harmful to their hosts. To reveal the roles of viruses in the virus-host interactions, viromes and microbiomes of sediment samples from three deep-sea hydrothermal vents were explored in this study. To exclude the influence of exogenous DNAs on viromes, the virus particles were purified with nuclease (DNase I and RNase A) treatments and cesium chloride density gradient centrifugation. The metagenomic analysis of viromes without exogenous DNA contamination and microbiomes of vent samples indicated that viruses had compensation effects on the metabolisms of their host microorganisms. Viral genes not only participated in most of the microbial metabolic pathways but also formed branched pathways in microbial metabolisms, including pyrimidine metabolism; alanine, aspartate, and glutamate metabolism; nitrogen metabolism and assimilation pathways of the two-component system; selenocompound metabolism; aminoacyl-tRNA biosynthesis; and amino sugar and nucleotide sugar metabolism. As is well known, deep-sea hydrothermal vent ecosystems exist in relatively isolated environments which are barely influenced by other ecosystems. The metabolic compensation of hosts mediated by viruses might represent a very important aspect of virus-host interactions.

Viruses are the most abundant biological entities in the oceans and have very important roles in regulating microbial community structure and biogeochemical cycles. The relationship between virus and host microbes is broadly thought to be that of predator and prey. Viruses can lyse host cells to control microbial population sizes and affect community structures of hosts by killing specific microbes. However, viruses also influence their hosts through manipulation of bacterial metabolism. We found that viral genes not only participated in most microbial metabolic pathways but also formed branched pathways in microbial metabolisms. The metabolic compensation of hosts mediated by viruses may help hosts to adapt to extreme environments and may be essential for host survival.

Genomic, proteomic and bioinformatic analysis of two temperate phages in Roseobacter clade bacteria isolated from the deep-sea water

Background

Marine phages are spectacularly diverse in nature. Dozens of roseophages infecting members of Roseobacter clade bacteria were isolated and characterized, exhibiting a very high degree of genetic diversity. In the present study, the induction of two temperate bacteriophages, namely, vB_ThpS-P1 and vB_PeaS-P1, was performed in Roseobacter clade bacteria isolated from the deep-sea water, Thiobacimonas profunda JLT2016 and Pelagibaca abyssi JLT2014, respectively. Two novel phages in morphological, genomic and proteomic features were presented, and their phylogeny and evolutionary relationships were explored by bioinformatic analysis.

Results

Electron microscopy showed that the morphology of the two phages were similar to that of siphoviruses. Genome sequencing indicated that the two phages were similar in size, organization, and content, thereby suggesting that these shared a common ancestor. Despite the presence of Mu-like phage head genes, the phages are more closely related to Rhodobacter phage RC1 than Mu phages in terms of gene content and sequence similarity. Based on comparative genomic and phylogenetic analysis, we propose a Mu-like head phage group to allow for the inclusion of Mu-like phages and two newly phages. The sequences of the Mu-like head phage group were widespread, occurring in each investigated metagenomes. Furthermore, the horizontal exchange of genetic material within the Mu-like head phage group might have involved a gene that was associated with phage phenotypic characteristics.

Conclusions

This study is the first report on the complete genome sequences of temperate phages that infect deep-sea roseobacters, belonging to the Mu-like head phage group. The Mu-like head phage group might represent a small but ubiquitous fraction of marine viral diversity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3886-0) contains supplementary material, which is available to authorized users.

Characterization of the interaction between superoxide dismutase and 2-oxoisovalerate dehydrogenase

Thermophiles are attractive microorganisms to study the adaptation of life in high temperature environment. It is revealed that superoxide dismutase (SOD) is essential for thermoadaptation of thermophiles. However, the SOD-mediated pathway of thermoadaptation remains unclear. To address this issue, the proteins interacted with SOD were characterized in Thermus thermophilus in this study. Based on co-immunoprecipitation and Western blot analyses, the results showed that 2-oxoisovalerate dehydrogenase α subunit was bound to SOD. The isothermal titration calorimetry analysis showed the existence of the interaction between SOD and 2-oxoisovalerate dehydrogenase α subunit. The bacterial two-hybrid data indicated that SOD was directly interacted with 2-oxoisovalerate dehydrogenase α subunit. Gene site-directed mutagenesis analysis revealed that the intracellular interaction between SOD and 2-oxoisovalerate dehydrogenase α subunit was dependent on their whole molecules. Therefore our study presented a novel aspect of SOD in the thermoadaptation of thermophiles by interaction with dehydrogenase, a key enzyme of tricarboxylic acid cycle.

Identification and characterization of a novel Geobacillus thermoglucosidasius bacteriophage, GVE3

The study of extremophilic phages may reveal new phage families as well as different mechanisms of infection, propagation and lysis to those found in phages from temperate environments. We describe a novel siphovirus, GVE3, which infects the thermophile Geobacillus thermoglucosidasius. The genome size is 141,298 bp (G+C 29.6%), making it the largest Geobacillus spp-infecting phage known. GVE3 appears to be most closely related to the recently described Bacillus anthracis phage vB_BanS_Tsamsa, rather than Geobacillus-infecting phages described thus far. Tetranucleotide usage deviation analysis supports this relationship, showing that the GVE3 genome sequence correlates best with B. anthracis and Bacillus cereus genome sequences, rather than Geobacillus spp genome sequences.

Identification and genomic analysis of temperate Pseudomonas bacteriophage PstS-1 from the Japan trench at a depth of 7000 m

Viruses play important roles in aquatic ecosystems, but deep-sea bacteriophages remain largely unexplored. A temperate bacteriophage (termed vB_PstS-1) was identified from the psychrotolerant gammaproteobacterium Pseudomonas stutzeri 1-1-1b, which was isolated from hadopelagic water (depth of 7000 m) of the Japan Trench in the Northwest Pacific Ocean. The genome size of PstS-1 was 48,666 bp; its genome displayed a 59.8% G + C content and a total of 79 coding sequences were identified in its genome. The PstS-1 phage belongs to the family Siphoviridae, but its genomic sequence and organization are distinct from those of any other well-known Siphoviridae phage. The mosaic genomic structure of PstS-1 suggests the occurrence of genetic exchange between distinct temperate phages in deep-sea Pseudomonas populations. The PstS-1 genome also harbors three distinct sequence regions corresponding to spacers within a single clustered regularly interspaced short palindromic repeat (CRISPR) locus in the rhizosphere-associated diazotrophic P. stutzeri A1501 genome. The extension of these spacers to the soil environment and the presence of many homologs of both the hadal deep-sea phage PstS-1 and terrestrial Pseudomonas phages suggest the early co-evolution of temperate phages and their host genus Pseudomonas prior to the divergence of their habitational and physiological adaptation.

Genomic characterization of a temperate phage of the psychrotolerant deep-sea bacterium Aurantimonas sp

A temperate phage (termed AmM-1) was identified from the psychrotolerant Rhizobiales bacterium Aurantimonas sp. C5-1, which was isolated from bathypelagic water (water depth = 1,500 m) in the northwest Pacific. The AmM-1 genome is 47,800 bp in length and contains 67 coding sequences. Although phage AmM-1 morphologically belongs to the family Myoviridae, its genomic structure, particularly modular genome organization, is similar to that of lambda-type phages of Siphoviridae. Genetic and phylogenetic analyses of the structural core genes also revealed that AmM-1 has a mosaic genomic structure that includes a lambda-like head (Siphoviridae) and P2-like tail (Myoviridae). The sequences of the structural core genes of AmM-1 are distinct from those of previously characterized phage groups but similar to those of recently identified one prophage element and one phage of marine Rhizobiales bacteria: a potential prophage element in the marine psychrotolerant Aureimonas ureilytica DSM 18598 genome and the temperate phage RR-1A infecting Rhizobium radiobacter P007 isolated from deep subseafloor sediment. The mosaic genome structure of AmM-1 suggests the occurrence of genetic exchange between distinct temperate phages in marine Rhizobiales populations.

Isolation, growth and genome of the Rhodothermus RM378 thermophilic bacteriophage

Several bacteriophages that infect different strains of the thermophilic bacterium Rhodothermus marinus were isolated and their infection pattern was studied. One phage, named RM378 was cultivated and characterized. The RM378 genome was also sequenced and analyzed. The phage was grouped as a member of the Myoviridae family with A2 morphology. It had a moderately elongated head, with dimensions of 85 and 95 nm between opposite apices and a 150 nm long tail, attached with a connector to the head. RM378 showed a virulent behavior that followed a lytic cycle of infection. It routinely gave lysates with 10(11) pfu/ml, and sometimes reached titers as high as 10(13) pfu/ml. The titer remained stable up to 65 °C but the phage lost viability when incubated at higher temperatures. Heating for 30 min at 96 °C lowered the titer by 10(4). The RM378 genome consisted of ds DNA of 129.908 bp with a GC ratio of 42.0% and contained about 120 ORFs. A few structural proteins, such as the major head protein corresponding to the gp23 in T4, could be identified. Only 29 gene products as probable homologs to other proteins of known function could be predicted, with most showing only low similarity to known proteins in other bacteriophages. These and other studies based on sequence analysis of a large number of phage genomes showed RM378 to be distantly related to all other known T4-like phages.

Draft Genome Sequence of Geobacillus kaustophilus GBlys, a Lysogenic Strain with Bacteriophage OH2

Geobacillus kaustophilus strain GBlys was isolated along with the bacteriophage ϕOH2, which infects G. kaustophilus NBRC 102445^T. Here we present a draft sequence of this strain’s genome, which consists of 216 contigs for a total of 3,541,481 bp, 3,679 predicted coding sequences, and a G+C content of 52.1%.

Genome sequence of a novel deep-sea vent epsilonproteobacterial phage provides new insight into the co-evolution of Epsilonproteobacteria and their phages

Epsilonproteobacteria are among the predominant primary producers in deep-sea hydrothermal vent ecosystems. However, phages infecting deep-sea vent Epsilonproteobacteria have never been isolated and characterized. Here, we successfully isolated a novel temperate phage, NrS-1, that infected a deep-sea vent chemolithoautotrophic isolate of Epsilonproteobacteria, Nitratiruptor sp. SB155-2, and its entire genome sequence was obtained and analyzed. The NrS-1 genome is linear, circularly permuted, and terminally redundant. The NrS-1 genome is 37,159 bp in length and contains 51 coding sequences. Five major structural proteins including major capsid protein and tape measure protein were identified by SDS-PAGE and mass spectrometry analysis. NrS-1 belongs to the family Siphoviridae, but its sequence and genomic organization are distinct from those of any other previously known Siphoviridae phages. Homologues of genes encoded in the NrS-1 genome were widely distributed among the genomes of diverse Epsilonproteobacteria. The distribution patterns had little relation to the evolutionary traits and ecological and physiological differentiation of the host epsilonproteobacterial species. The widespread occurrence of phage genes in diverse Epsilonproteobacteria supports early co-evolution between temperate phages and Epsilonproteobacteria prior to the divergence of their habitats and physiological adaptation.

The role of interactions between bacterial chaperone, aspartate aminotransferase, and viral protein during virus infection in high temperature environment: the interactions between bacterium and virus proteins

Background

The life cycle of a bacteriophage has tightly programmed steps to help virus infect its host through the interactions between the bacteriophage and its host proteins. However, bacteriophage–host protein interactions in high temperature environment remain poorly understood. To address this issue, the protein interaction between the thermophilic bacteriophage GVE2 and its host thermophilic Geobacillus sp. E263 from a deep-sea hydrothermal vent was characterized.

Results

This investigation showed that the host’s aspartate aminotransferase (AST), chaperone GroEL, and viral capsid protein VP371 formed a linearly interacted complex. The results indicated that the VP371-GroEL-AST complex were up-regulated and co-localized in the GVE2 infection of Geobacillus sp. E263.

Conclusions

As reported, the VP371 is a capsid protein of GVE2 and the host AST is essential for the GVE2 infection. Therefore, our study revealed that the phage could use the anti-stress system of its host to protect the virus reproduction in a high-temperature environment for the first time.

Novel bacteriophages containing a genome of another bacteriophage within their genomes

A novel bacteriophage infecting Staphylococus pasteuri was isolated during a screen for phages in Antarctic soils. The phage named SpaA1 is morphologically similar to phages of the family Siphoviridae. The 42,784 bp genome of SpaA1 is a linear, double-stranded DNA molecule with 3' protruding cohesive ends. The SpaA1 genome encompasses 63 predicted protein-coding genes which cluster within three regions of the genome, each of apparently different origin, in a mosaic pattern. In two of these regions, the gene sets resemble those in prophages of Bacillus thuringiensis kurstaki str. T03a001 (genes involved in DNA replication/transcription, cell entry and exit) and B. cereus AH676 (additional regulatory and recombination genes), respectively. The third region represents an almost complete genome (except for the short terminal segments) of a distinct bacteriophage, MZTP02. Nearly the same gene module was identified in prophages of B. thuringiensis serovar monterrey BGSC 4AJ1 and B. cereus Rock4-2. These findings suggest that MZTP02 can be shuttled between genomes of other bacteriophages and prophages, leading to the formation of chimeric genomes. The presence of a complete phage genome in the genome of other phages apparently has not been described previously and might represent a 'fast track' route of virus evolution and horizontal gene transfer. Another phage (BceA1) nearly identical in sequence to SpaA1, and also including the almost complete MZTP02 genome within its own genome, was isolated from a bacterium of the B. cereus/B. thuringiensis group. Remarkably, both SpaA1 and BceA1 phages can infect B. cereus and B. thuringiensis, but only one of them, SpaA1, can infect S. pasteuri. This finding is best compatible with a scenario in which MZTP02 was originally contained in BceA1 infecting Bacillus spp, the common hosts for these two phages, followed by emergence of SpaA1 infecting S. pasteuri.