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1.
Viruses ; 16(4)2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-38675830

RESUMO

The molecular mechanism of how the infecting DNA of bacteriophage T4 passes from the capsid through the bacterial cell wall and enters the cytoplasm is essentially unknown. After adsorption, the short tail fibers of the infecting phage extend from the baseplate and trigger the contraction of the tail sheath, leading to a puncturing of the outer membrane by the tail tip needle composed of the proteins gp5.4, gp5 and gp27. To explore the events that occur in the periplasm and at the inner membrane, we constructed T4 phages that have a modified gp27 in their tail tip with a His-tag. Shortly after infection with these phages, cells were chemically cross-linked and solubilized. The cross-linked products were affinity-purified on a nickel column and the co-purified proteins were identified by mass spectrometry, and we found that predominantly the inner membrane proteins DamX, SdhA and PpiD were cross-linked. The same partner proteins were identified when purified gp27 was added to Escherichia coli spheroplasts, suggesting a direct protein-protein interaction.


Assuntos
Bacteriófago T4 , Escherichia coli , Bacteriófago T4/fisiologia , Bacteriófago T4/genética , Bacteriófago T4/metabolismo , Bacteriófago T4/química , Escherichia coli/virologia , Escherichia coli/genética , Escherichia coli/metabolismo , Divisão Celular , Proteínas de Escherichia coli/metabolismo , Proteínas Virais/metabolismo , Proteínas Virais/genética
2.
Nature ; 629(8011): 410-416, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38632404

RESUMO

Bacteria have adapted to phage predation by evolving a vast assortment of defence systems1. Although anti-phage immunity genes can be identified using bioinformatic tools, the discovery of novel systems is restricted to the available prokaryotic sequence data2. Here, to overcome this limitation, we infected Escherichia coli carrying a soil metagenomic DNA library3 with the lytic coliphage T4 to isolate clones carrying protective genes. Following this approach, we identified Brig1, a DNA glycosylase that excises α-glucosyl-hydroxymethylcytosine nucleobases from the bacteriophage T4 genome to generate abasic sites and inhibit viral replication. Brig1 homologues that provide immunity against T-even phages are present in multiple phage defence loci across distinct clades of bacteria. Our study highlights the benefits of screening unsequenced DNA and reveals prokaryotic DNA glycosylases as important players in the bacteria-phage arms race.


Assuntos
Bacteriófago T4 , DNA Glicosilases , Escherichia coli , Escherichia coli/genética , Escherichia coli/virologia , DNA Glicosilases/metabolismo , Bacteriófago T4/enzimologia , Bacteriófago T4/genética , Replicação Viral , Fagos T/metabolismo , Fagos T/genética , Genoma Viral/genética , Microbiologia do Solo , Metagenômica , Filogenia
3.
J Chem Inf Model ; 64(8): 3269-3277, 2024 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-38546407

RESUMO

The use of computer simulation for binding affinity prediction is growing in drug discovery. However, its wider use is constrained by the accuracy of the free energy calculations. The key sources of error are the force fields used to depict molecular interactions and insufficient sampling of the configurational space. To improve the quality of the force field, we developed a Python-based computational workflow. The workflow described here uses the minimal basis iterative stockholder (MBIS) method to determine atomic charges and Lennard-Jones parameters from the polarized molecular density. This is done by performing electronic structure calculations on various configurations of the ligand when it is both bound and unbound. In addition, we validated a simulation procedure that accounts for the protein and ligand degrees of freedom to precisely calculate binding free energies. This was achieved by comparing the self-adjusted mixture sampling and nonequilibrium thermodynamic integration methods using various protein and ligand conformations. The accuracy of predicting binding affinity is improved by using MBIS-derived force field parameters and a validated simulation procedure. This improvement surpasses the chemical precision for the eight aromatic ligands, reaching a root-mean-square error of 0.7 kcal/mol.


Assuntos
Muramidase , Ligação Proteica , Termodinâmica , Muramidase/química , Muramidase/metabolismo , Ligantes , Elétrons , Bacteriófago T4/enzimologia , Mutação , Conformação Proteica , Simulação de Dinâmica Molecular , Modelos Moleculares
4.
J Mol Biol ; 436(9): 168544, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38508303

RESUMO

Bacteriophage T4 gene 32 protein (gp32) is a single-stranded DNA (ssDNA) binding protein essential for DNA replication. gp32 forms stable protein filaments on ssDNA through cooperative interactions between its core and N-terminal domain. gp32's C-terminal domain (CTD) is believed to primarily help coordinate DNA replication via direct interactions with constituents of the replisome. However, the exact mechanisms of these interactions are not known, and it is unclear how tightly-bound gp32 filaments are readily displaced from ssDNA as required for genomic processing. Here, we utilized truncated gp32 variants to demonstrate a key role of the CTD in regulating gp32 dissociation. Using optical tweezers, we probed the binding and dissociation dynamics of CTD-truncated gp32, *I, to an 8.1 knt ssDNA molecule and compared these measurements with those for full-length gp32. The *I-ssDNA helical filament becomes progressively unwound with increased protein concentration but remains significantly more stable than that of full-length, wild-type gp32. Protein oversaturation, concomitant with filament unwinding, facilitates rapid dissociation of full-length gp32 from across the entire ssDNA segment. In contrast, *I primarily unbinds slowly from only the ends of the cooperative clusters, regardless of the protein density and degree of DNA unwinding. Our results suggest that the CTD may constrain the relative twist angle of proteins within the ssDNA filament such that upon critical unwinding the cooperative interprotein interactions largely vanish, facilitating prompt removal of gp32. We propose a model of CTD-mediated gp32 displacement via internal restructuring of its filament, providing a mechanism for rapid ssDNA clearing during genomic processing.


Assuntos
Bacteriófago T4 , DNA de Cadeia Simples , Proteínas de Ligação a DNA , Ligação Proteica , Proteínas Virais , Bacteriófago T4/genética , Bacteriófago T4/metabolismo , Replicação do DNA , DNA de Cadeia Simples/metabolismo , DNA de Cadeia Simples/genética , DNA Viral/genética , DNA Viral/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/química , Pinças Ópticas , Domínios Proteicos , Proteínas Virais/metabolismo , Proteínas Virais/genética , Proteínas Virais/química
5.
Viruses ; 16(2)2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38399968

RESUMO

In all tailed phages, the packaging of the double-stranded genome into the head by a terminase motor complex is an essential step in virion formation. Despite extensive research, there are still major gaps in the understanding of this highly dynamic process and the mechanisms responsible for DNA translocation. Over the last fifteen years, single-molecule fluorescence technologies have been applied to study viral nucleic acid packaging using the robust and flexible T4 in vitro packaging system in conjunction with genetic, biochemical, and structural analyses. In this review, we discuss the novel findings from these studies, including that the T4 genome was determined to be packaged as an elongated loop via the colocalization of dye-labeled DNA termini above the portal structure. Packaging efficiency of the TerL motor was shown to be inherently linked to substrate structure, with packaging stalling at DNA branches. The latter led to the design of multiple experiments whose results all support a proposed torsional compression translocation model to explain substrate packaging. Evidence of substrate compression was derived from FRET and/or smFRET measurements of stalled versus resolvase released dye-labeled Y-DNAs and other dye-labeled substrates relative to motor components. Additionally, active in vivo T4 TerS fluorescent fusion proteins facilitated the application of advanced super-resolution optical microscopy toward the visualization of the initiation of packaging. The formation of twin TerS ring complexes, each expected to be ~15 nm in diameter, supports a double protein ring-DNA synapsis model for the control of packaging initiation, a model that may help explain the variety of ring structures reported among pac site phages. The examination of the dynamics of the T4 packaging motor at the single-molecule level in these studies demonstrates the value of state-of-the-art fluorescent tools for future studies of complex viral replication mechanisms.


Assuntos
Bacteriófago T4 , DNA Viral , DNA Viral/metabolismo , Bacteriófago T4/genética , Fluorescência , Montagem de Vírus , Empacotamento do DNA , Endodesoxirribonucleases/metabolismo
6.
J Vis Exp ; (203)2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38345223

RESUMO

Bacteriophages (phages) are viruses that infect bacteria with species- and strain-level specificity and are the most abundant biological entities across all known ecosystems. Within bacterial communities, such as those found in the gut microbiota, phages are implicated in regulating microbiota population dynamics and driving bacterial evolution. There has been renewed interest in phage research in the last decade, in part due to the host-specific killing capabilities of lytic phages, which offer a promising tool to counter the increasing threat of antimicrobial resistant bacteria. Furthermore, recent studies demonstrating that phages adhere to intestinal mucus suggest they may have a protective role in preventing bacterial invasion into the underlying epithelium. Importantly, like bacterial microbiomes, disrupted phageomes have been associated with worsened outcomes in diseases such as inflammatory bowel disease. Previous studies have demonstrated that phages can modulate the microbiome of animals and humans through fecal filtrate transplants, benefiting the host's health. With this recent wave of research comes the necessity to establish and standardize protocols for studying phages in the context of the gut microbiome. This protocol provides a set of procedures to study isolated T4 phages and their bacterial host, Escherichia coli, in the context of the murine gastrointestinal tract. The methods described here outline how to start from a phage lysate, administer it to mice and assess effects on bacterial host and phage levels. This protocol can be modified and applied to other phage-bacterial pairs and provides a starting point for studying host-phage dynamics in vivo.


Assuntos
Bacteriófagos , Microbiota , Humanos , Camundongos , Animais , Bacteriófagos/fisiologia , Bacteriófago T4 , Escherichia coli , Trato Gastrointestinal/microbiologia , Intestinos , Bactérias
7.
Int J Biol Macromol ; 258(Pt 1): 128837, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38128800

RESUMO

Foot-and-mouth disease virus (FMDV) is a highly contagious pathogen that has caused significant economic losses in the livestock industry. Peptide vaccines engineered with the protective epitopes of FMDV have provided a safer alternative for disease prevention than the traditional inactivated vaccines. However, the immunogenicity of the peptide is usually poor and therefore an adjuvant is required. Here, we showed that recombinant T4 phages displaying the B-cell epitope of the FMDV VP1 protein (VP1130-158), without additional adjuvants, induced similar levels of antigen-specific IgG1 but higher levels of IgG2a compared to the peptide vaccine. Incorporation of a CD4+ T cell epitope, either 3A21-35 of FMDV 3A protein or P2830-844 of tetanus toxoid, further enhanced the immunogenicity of VP1-T4 phage nanoparticles. Interestingly, the extrinsic adjuvant cannot enhance the immunogenicity of the nanoparticles, indicating the intrinsic adjuvant activities of T4 phage. Furthermore, the recombinant T4 phage can be produced on a large scale within a short period of time at a relatively low-cost using Escherichia coli, heralding its potential in the development of a safe and effective FMDV vaccine.


Assuntos
Vírus da Febre Aftosa , Febre Aftosa , Vacinas Virais , Animais , Bacteriófago T4 , Febre Aftosa/prevenção & controle , Nanovacinas , Anticorpos Antivirais , Epitopos de Linfócito B , Adjuvantes Imunológicos , Proteínas do Capsídeo
8.
PLoS Biol ; 21(10): e3002341, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37883333

RESUMO

There is a growing appreciation that the direct interaction between bacteriophages and the mammalian host can facilitate diverse and unexplored symbioses. Yet the impact these bacteriophages may have on mammalian cellular and immunological processes is poorly understood. Here, we applied highly purified phage T4, free from bacterial by-products and endotoxins to mammalian cells and analyzed the cellular responses using luciferase reporter and antibody microarray assays. Phage preparations were applied in vitro to either A549 lung epithelial cells, MDCK-I kidney cells, or primary mouse bone marrow derived macrophages with the phage-free supernatant serving as a comparative control. Highly purified T4 phages were rapidly internalized by mammalian cells and accumulated within macropinosomes but did not activate the inflammatory DNA response TLR9 or cGAS-STING pathways. Following 8 hours of incubation with T4 phage, whole cell lysates were analyzed via antibody microarray that detected expression and phosphorylation levels of human signaling proteins. T4 phage application led to the activation of AKT-dependent pathways, resulting in an increase in cell metabolism, survival, and actin reorganization, the last being critical for macropinocytosis and potentially regulating a positive feedback loop to drive further phage internalization. T4 phages additionally down-regulated CDK1 and its downstream effectors, leading to an inhibition of cell cycle progression and an increase in cellular growth through a prolonged G1 phase. These interactions demonstrate that highly purified T4 phages do not activate DNA-mediated inflammatory pathways but do trigger protein phosphorylation cascades that promote cellular growth and survival. We conclude that mammalian cells are internalizing bacteriophages as a resource to promote cellular growth and metabolism.


Assuntos
Anticorpos , Bacteriófago T4 , Animais , Camundongos , Humanos , Bacteriófago T4/genética , Ciclo Celular , DNA , Mamíferos/genética
9.
Sci Rep ; 13(1): 16207, 2023 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-37758721

RESUMO

Immobilization of bacteriophages onto solid supports such as magnetic particles has demonstrated ultralow detection limits as biosensors for the separation and detection of their host bacteria. While the potential impact of magnetized phages is high, the current methods of immobilization are either weak, costly, inefficient, or laborious making them less viable for commercialization. In order to bridge this gap, we have developed a highly efficient, site-specific, and low-cost method to immobilize bacteriophages onto solid supports. While streptavidin-biotin represents an ideal conjugation method, the functionalization of magnetic particles with streptavidin requires square meters of coverage and therefore is not amenable to a low-cost assay. Here, we genetically engineered bacteriophages to allow synthesis of a monomeric streptavidin during infection of the bacterial host. The monomeric streptavidin was fused to a capsid protein (Hoc) to allow site-specific self-assembly of up to 155 fusion proteins per capsid. Biotin coated magnetic nanoparticles were functionalized with mSA-Hoc T4 phage demonstrated in an E. coli detection assay with a limit of detection of < 10 CFU in 100 mLs of water. This work highlights the creation of genetically modified bacteriophages with a novel capsid modification, expanding the potential for bacteriophage functionalized biotechnologies.


Assuntos
Bacteriófagos , Bacteriófagos/genética , Bacteriófagos/metabolismo , Estreptavidina/metabolismo , Biotina/metabolismo , Escherichia coli/genética , Bacteriófago T4/genética , Bactérias , Fenômenos Magnéticos
10.
Nucleic Acids Res ; 51(19): 10506-10518, 2023 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-37739410

RESUMO

Replication protein A (RPA) binds single-stranded DNA (ssDNA) and serves critical functions in eukaryotic DNA replication, the DNA damage response, and DNA repair. During DNA replication, RPA is required for extended origin DNA unwinding and DNA synthesis. To determine the requirements for RPA during these processes, we tested ssDNA-binding proteins (SSBs) from different domains of life in reconstituted Saccharomyces cerevisiae origin unwinding and DNA replication reactions. Interestingly, Escherichia coli SSB, but not T4 bacteriophage Gp32, fully substitutes for RPA in promoting origin DNA unwinding. Using RPA mutants, we demonstrated that specific ssDNA-binding properties of RPA are required for origin unwinding but that its protein-interaction domains are dispensable. In contrast, we found that each of these auxiliary RPA domains have distinct functions at the eukaryotic replication fork. The Rfa1 OB-F domain negatively regulates lagging-strand synthesis, while the Rfa2 winged-helix domain stimulates nascent strand initiation. Together, our findings reveal a requirement for specific modes of ssDNA binding in the transition to extensive origin DNA unwinding and identify RPA domains that differentially impact replication fork function.


Assuntos
Replicação do DNA , Proteínas de Ligação a DNA , Proteína de Replicação A , DNA de Cadeia Simples/genética , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/metabolismo , Ligação Proteica , Proteína de Replicação A/genética , Proteína de Replicação A/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Bacteriófago T4/metabolismo
11.
Viruses ; 15(8)2023 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-37632079

RESUMO

The preservative qualities of individual ionic compounds impacting the infectivity of T4 virions were elucidated. T4 virions were immersed in quasi-pure ionic solutions prior to the adsorption process, and the plaque forming unit (pfu) values of these were measured following the conventional method. In neutral ionic solutions, the minimum and the optimum concentrations of preservative qualities corresponded with the results obtained from the multi-ionic media/buffers. In acid and alkali solutions, phages show tolerances at a pH range of 5-11 in multi-ionic media/buffers. T4 virions show no tolerance in quasi-pure acid, neutral, and weak alkaline conditions. The preservative quality of T4 virions increased in over 10-1 mM OH- solution, equivalent to a pH value over 10, which corresponds to the pKa of the deprotonation of the DNA bases G and T. Infectivity was lost below 10-1 mM OH- and higher than 10 mM OH-. These results imply that maintaining infectivity of a virion may need the flexibility of the intra-capsid DNA by deprotonation.


Assuntos
Bacteriófago T4 , Capsídeo , Adsorção , Proteínas do Capsídeo
12.
Nature ; 620(7976): 1054-1062, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37587340

RESUMO

The mechanisms by which viruses hijack the genetic machinery of the cells they infect are of current interest. When bacteriophage T4 infects Escherichia coli, it uses three different adenosine diphosphate (ADP)-ribosyltransferases (ARTs) to reprogram the transcriptional and translational apparatus of the host by ADP-ribosylation using nicotinamide adenine dinucleotide (NAD) as a substrate1,2. NAD has previously been identified as a 5' modification of cellular RNAs3-5. Here we report that the T4 ART ModB accepts not only NAD but also NAD-capped RNA (NAD-RNA) as a substrate and attaches entire RNA chains to acceptor proteins in an 'RNAylation' reaction. ModB specifically RNAylates the ribosomal proteins rS1 and rL2 at defined Arg residues, and selected E. coli and T4 phage RNAs are linked to rS1 in vivo. T4 phages that express an inactive mutant of ModB have a decreased burst size and slowed lysis of E. coli. Our findings reveal a distinct biological role for NAD-RNA, namely the activation of the RNA for enzymatic transfer to proteins. The attachment of specific RNAs to ribosomal proteins might provide a strategy for the phage to modulate the host's translation machinery. This work reveals a direct connection between RNA modification and post-translational protein modification. ARTs have important roles far beyond viral infections6, so RNAylation may have far-reaching implications.


Assuntos
ADP Ribose Transferases , Bacteriófago T4 , Proteínas de Escherichia coli , Escherichia coli , NAD , RNA , Proteínas Virais , ADP Ribose Transferases/metabolismo , Bacteriófago T4/enzimologia , Bacteriófago T4/genética , Bacteriófago T4/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Escherichia coli/virologia , NAD/metabolismo , Proteínas Ribossômicas/química , Proteínas Ribossômicas/metabolismo , Proteínas Virais/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , RNA/química , RNA/genética , RNA/metabolismo , Biossíntese de Proteínas , Regulação Bacteriana da Expressão Gênica , Processamento de Proteína Pós-Traducional
13.
Nucleic Acids Res ; 51(16): 8587-8605, 2023 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-37449435

RESUMO

Bacteriophage T4 gene 32 protein (gp32) is a model single-stranded DNA (ssDNA) binding protein, essential for DNA replication. gp32 forms cooperative filaments on ssDNA through interprotein interactions between its core and N-terminus. However, detailed understanding of gp32 filament structure and organization remains incomplete, particularly for longer, biologically-relevant DNA lengths. Moreover, it is unclear how these tightly-bound filaments dissociate from ssDNA during complementary strand synthesis. We use optical tweezers and atomic force microscopy to probe the structure and binding dynamics of gp32 on long (∼8 knt) ssDNA substrates. We find that cooperative binding of gp32 rigidifies ssDNA while also reducing its contour length, consistent with the ssDNA helically winding around the gp32 filament. While measured rates of gp32 binding and dissociation indicate nM binding affinity, at ∼1000-fold higher protein concentrations gp32 continues to bind into and restructure the gp32-ssDNA filament, leading to an increase in its helical pitch and elongation of the substrate. Furthermore, the oversaturated gp32-ssDNA filament becomes progressively unwound and unstable as observed by the appearance of a rapid, noncooperative protein dissociation phase not seen at lower complex saturation, suggesting a possible mechanism for prompt removal of gp32 from the overcrowded ssDNA in front of the polymerase during replication.


Assuntos
Bacteriófago T4 , Proteínas Virais , Bacteriófago T4/metabolismo , DNA Helicases/genética , Replicação do DNA , DNA de Cadeia Simples/genética , DNA de Cadeia Simples/metabolismo , DNA Viral/genética , Proteínas de Ligação a DNA/metabolismo , Ligação Proteica , Proteínas Virais/metabolismo
14.
Viruses ; 15(7)2023 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-37515203

RESUMO

Bacteriophage T4 is decorated with 155 180 Å-long fibers of the highly antigenic outer capsid protein (Hoc). In this study, we describe a near-atomic structural model of Hoc by combining cryo-electron microscopy and AlphaFold structure predictions. It consists of a conserved C-terminal capsid-binding domain attached to a string of three variable immunoglobulin (Ig)-like domains, an architecture well-preserved in hundreds of Hoc molecules found in phage genomes. Each T4-Hoc fiber attaches randomly to the center of gp23* hexameric capsomers in one of the six possible orientations, though at the vertex-proximal hexamers that deviate from 6-fold symmetry, Hoc binds in two preferred orientations related by 180° rotation. Remarkably, each Hoc fiber binds to all six subunits of the capsomer, though the interactions are greatest with three of the subunits, resulting in the off-centered attachment of the C-domain. Biochemical analyses suggest that the acidic Hoc fiber (pI, ~4-5) allows for the clustering of virions in acidic pH and dispersion in neutral/alkaline pH. Hoc appears to have evolved as a sensing device that allows the phage to navigate its movements through reversible clustering-dispersion transitions so that it reaches its destination, the host bacterium, and persists in various ecological niches such as the human/mammalian gut.


Assuntos
Bacteriófagos , Animais , Humanos , Bacteriófagos/genética , Bacteriófagos/metabolismo , Microscopia Crioeletrônica/métodos , Proteínas do Capsídeo/química , Capsídeo/metabolismo , Bacteriófago T4/genética , Bacteriófago T4/química , Ligação Proteica , Mamíferos
15.
Antiviral Res ; 217: 105688, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37516153

RESUMO

Vaccines that trigger mucosal immune responses at the entry portals of pathogens are highly desired. Here, we showed that antigen-decorated nanoparticle generated through CRISPR engineering of T4 bacteriophage can serve as a universal platform for the rapid development of mucosal vaccines. Insertion of Flu viral M2e into phage T4 genome through fusion to Soc (Small Outer Capsid protein) generated a recombinant phage, and the Soc-M2e proteins self-assembled onto phage capsids to form 3M2e-T4 nanoparticles during propagation of T4 in E. coli. Intranasal administration of 3M2e-T4 nanoparticles maintains antigen persistence in the lungs, resulting in increased uptake and presentation by antigen-presenting cells. M2e-specific secretory IgA, effector (TEM), central (TCM), and tissue-resident memory CD4+ T cells (TRM) were efficiently induced in the local mucosal sites, which mediated protections against divergent influenza viruses. Our studies demonstrated the mechanisms of immune protection following 3M2e-T4 nanoparticles vaccination and provide a versatile T4 platform that can be customized to rapidly develop mucosal vaccines against future emerging epidemics.


Assuntos
Vacinas contra Influenza , Nanopartículas , Infecções por Orthomyxoviridae , Animais , Camundongos , Vacinas contra Influenza/genética , Bacteriófago T4/genética , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Escherichia coli/genética , Infecções por Orthomyxoviridae/prevenção & controle , Camundongos Endogâmicos BALB C , Proteínas da Matriz Viral
16.
Nat Commun ; 14(1): 4052, 2023 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-37422479

RESUMO

E217 is a Pseudomonas phage used in an experimental cocktail to eradicate cystic fibrosis-associated Pseudomonas aeruginosa. Here, we describe the structure of the whole E217 virion before and after DNA ejection at 3.1 Å and 4.5 Å resolution, respectively, determined using cryogenic electron microscopy (cryo-EM). We identify and build de novo structures for 19 unique E217 gene products, resolve the tail genome-ejection machine in both extended and contracted states, and decipher the complete architecture of the baseplate formed by 66 polypeptide chains. We also determine that E217 recognizes the host O-antigen as a receptor, and we resolve the N-terminal portion of the O-antigen-binding tail fiber. We propose that E217 design principles presented in this paper are conserved across PB1-like Myoviridae phages of the Pbunavirus genus that encode a ~1.4 MDa baseplate, dramatically smaller than the coliphage T4.


Assuntos
Fagos de Pseudomonas , Fagos de Pseudomonas/genética , Microscopia Crioeletrônica , Antígenos O , Microscopia Eletrônica , Myoviridae , Bacteriófago T4/química
17.
Nat Commun ; 14(1): 4396, 2023 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-37474605

RESUMO

The T4 bacteriophage gp41 helicase and gp61 primase assemble into a primosome to couple DNA unwinding with RNA primer synthesis for DNA replication. How the primosome is assembled and how the primer length is defined are unclear. Here we report a series of cryo-EM structures of T4 primosome assembly intermediates. We show that gp41 alone is an open spiral, and ssDNA binding triggers a large-scale scissor-like conformational change that drives the ring closure and activates the helicase. Helicase activation exposes a cryptic hydrophobic surface to recruit the gp61 primase. The primase binds the helicase in a bipartite mode in which the N-terminal Zn-binding domain and the C-terminal RNA polymerase domain each contain a helicase-interacting motif that bind to separate gp41 N-terminal hairpin dimers, leading to the assembly of one primase on the helicase hexamer. Our study reveals the T4 primosome assembly process and sheds light on the RNA primer synthesis mechanism.


Assuntos
Bacteriófago T4 , DNA Primase , Bacteriófago T4/metabolismo , DNA Primase/metabolismo , DNA Helicases/metabolismo , Replicação do DNA , Primers do DNA/metabolismo , DNA Viral/metabolismo
18.
J Virol ; 97(6): e0059923, 2023 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-37306585

RESUMO

Many phages, such as T4, protect their genomes against the nucleases of bacterial restriction-modification (R-M) and CRISPR-Cas systems through covalent modification of their genomes. Recent studies have revealed many novel nuclease-containing antiphage systems, raising the question of the role of phage genome modifications in countering these systems. Here, by focusing on phage T4 and its host Escherichia coli, we depicted the landscape of the new nuclease-containing systems in E. coli and demonstrated the roles of T4 genome modifications in countering these systems. Our analysis identified at least 17 nuclease-containing defense systems in E. coli, with type III Druantia being the most abundant system, followed by Zorya, Septu, Gabija, AVAST type 4, and qatABCD. Of these, 8 nuclease-containing systems were found to be active against phage T4 infection. During T4 replication in E. coli, 5-hydroxymethyl dCTP is incorporated into the newly synthesized DNA instead of dCTP. The 5-hydroxymethylcytosines (hmCs) are further modified by glycosylation to form glucosyl-5-hydroxymethylcytosine (ghmC). Our data showed that the ghmC modification of the T4 genome abolished the defense activities of Gabija, Shedu, Restriction-like, type III Druantia, and qatABCD systems. The anti-phage T4 activities of the last two systems can also be counteracted by hmC modification. Interestingly, the Restriction-like system specifically restricts phage T4 containing an hmC-modified genome. The ghmC modification cannot abolish the anti-phage T4 activities of Septu, SspBCDE, and mzaABCDE, although it reduces their efficiency. Our study reveals the multidimensional defense strategies of E. coli nuclease-containing systems and the complex roles of T4 genomic modification in countering these defense systems. IMPORTANCE Cleavage of foreign DNA is a well-known mechanism used by bacteria to protect themselves from phage infections. Two well-known bacterial defense systems, R-M and CRISPR-Cas, both contain nucleases that cleave the phage genomes through specific mechanisms. However, phages have evolved different strategies to modify their genomes to prevent cleavage. Recent studies have revealed many novel nuclease-containing antiphage systems from various bacteria and archaea. However, no studies have systematically investigated the nuclease-containing antiphage systems of a specific bacterial species. In addition, the role of phage genome modifications in countering these systems remains unknown. Here, by focusing on phage T4 and its host Escherichia coli, we depicted the landscape of the new nuclease-containing systems in E. coli using all 2,289 genomes available in NCBI. Our studies reveal the multidimensional defense strategies of E. coli nuclease-containing systems and the complex roles of genomic modification of phage T4 in countering these defense systems.


Assuntos
Bacteriófago T4 , Enzimas de Restrição-Modificação do DNA , Escherichia coli , Bacteriófago T4/genética , Sistemas CRISPR-Cas , Escherichia coli/enzimologia , Escherichia coli/virologia , Genoma Viral
19.
Methods Mol Biol ; 2671: 79-94, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37308639

RESUMO

Protein cages and nanostructures are promising biocompatible medical materials, such as vaccines and drug carriers. Recent advances in designed protein nanocages and nanostructures have opened up cutting-edge applications in the fields of synthetic biology and biopharmaceuticals. A simple approach for constructing self-assembling protein nanocages and nanostructures is the design of a fusion protein composed of two different proteins forming symmetric oligomers. In this chapter, we describe the design and methods of protein nanobuilding blocks (PN-Blocks) using a dimeric de novo protein WA20 to construct self-assembling protein cages and nanostructures. A protein nanobuilding block (PN-Block), WA20-foldon, was developed by fusing an intermolecularly folded dimeric de novo protein WA20 and a trimeric foldon domain from bacteriophage T4 fibritin. The WA20-foldon self-assembled into several oligomeric nanoarchitectures in multiples of 6-mer. De novo extender protein nanobuilding blocks (ePN-Blocks) were also developed by fusing tandemly two WA20 with various linkers, to construct self-assembling cyclized and extended chain-like nanostructures. These PN-Blocks would be useful for the construction of self-assembling protein cages and nanostructures and their potential applications in the future.


Assuntos
Produtos Biológicos , Nanoestruturas , Bacteriófago T4 , Materiais Biocompatíveis , Portadores de Fármacos , Polímeros
20.
Nat Commun ; 14(1): 2928, 2023 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-37253769

RESUMO

Designing artificial viral vectors (AVVs) programmed with biomolecules that can enter human cells and carry out molecular repairs will have broad applications. Here, we describe an assembly-line approach to build AVVs by engineering the well-characterized structural components of bacteriophage T4. Starting with a 120 × 86 nm capsid shell that can accommodate 171-Kbp DNA and thousands of protein copies, various combinations of biomolecules, including DNAs, proteins, RNAs, and ribonucleoproteins, are externally and internally incorporated. The nanoparticles are then coated with cationic lipid to enable efficient entry into human cells. As proof of concept, we assemble a series of AVVs designed to deliver full-length dystrophin gene or perform various molecular operations to remodel human genome, including genome editing, gene recombination, gene replacement, gene expression, and gene silencing. These large capacity, customizable, multiplex, and all-in-one phage-based AVVs represent an additional category of nanomaterial that could potentially transform gene therapies and personalized medicine.


Assuntos
Bacteriófago T4 , Genoma Humano , Humanos , Bacteriófago T4/genética , Bacteriófago T4/metabolismo , Vetores Genéticos/genética , Proteínas do Capsídeo/metabolismo , Capsídeo/metabolismo , DNA Viral/genética
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