It is tadpole-shaped with polyhedral head, a short neck and collar and a straight tail. A tour-de-force of structural biology solves the structure of the macromolecular injection machinery used to deliver a phage genome into a bacterium. ... the phage and host synthases exhibit striking dissimilarities in both structure and function. The T4 52 protein (421 amino acids) is homologous to the N-terminal portion of the GyrA protein⦠13.2) is characterized by the presence of a hexagonal head about 900 Å wide. The structure consists of an N-terminal ATPase domain, which provides energy for compacting DNA, and a C-terminal nuclease domain, which terminates packaging. The T4 phage display system can also be used as an attractive approach for cancer therapy. 18.2). We have determined the crystal structure of the T4 UvsX recombinase, and the overall architecture and fold closely resemble those of ⦠In his early work, he identified two separate but very close loci within the r II region, which he suggested were nucleotide sequences that encoded different polypeptides ; he called these " cistrons ". The wild type T4 phage produces small plaques with rough edges on both strains B and K of E. coli. While holins are composed primarily of transmembrane α-helices , the holin from the T4 phage (T) is somewhat unique among the identified holins as having substantial cytoplasmic (~ 32 residues) and periplasmic (~ 150 residues) domains with only a single transmembrane domain . The structure of the phage T4 DNA packaging motor has been determined recently (7, 8). linear double-stranded DNA genome about 169 kbp long and encodes 289 DâHérelle coined the term bacteriophage, meaning âbacteria eater,â to describe the agentâs bacteriocidal ability. General effects of glucosylation and restriction on phage T4 gene expression and replication. Also the tail consists of about 35 stacked discs or annuli. During phage morphogenesis these whiskers bind the long tail fibers (LTFs) and facilitate their attachment to the phage baseplate. The key component of this process is the baseplate, located at the end of the phage tail, which regulates the interaction of the tail fibres and the DNA ejection machine. III. The derived amino acid sequences of the T4 genes can be aligned with those of the bacterial gyrB and gyrA genes: The T4 39 protein sequence (519 amino acids) can be aligned with the N-terminal portion of the GyrB protein and the T4 60 protein (160 amino acids) can be aligned with the C-terminal of the GyrB protein. M13 is one of the Ff phages (fd and f1 are others), a member of the family filamentous bacteriophage ().Ff phages are composed of circular single-stranded DNA which is 6407 nucleotides long encapsidated in approximately 2700 copies of the major coat protein p8, and capped with about 5 copies each of four different minor coat proteins (p3 and p6 at one end and p7 and p9 at the other end). The virus that infects only bacterial cells (bacteria eater) This study examines how the high-energy, dome-shaped infectious form of the bacteriophage T4 baseplate assembles as opposed to how it assembles in the low-energy, star-shaped form that occurs after infection. streisinger g, edgar rs, denhardt gh. T4 biology and its genomic sequence provide the best-understood model for ⦠Virology. 14.17). f ibers (f ig. The mutations were located in 47 different genes, 35 of which appeared to be involved in morphogenesis of the phage particles. For more information, log on to-http://shomusbiology.weebly.com/this bacteriophage lecture explains the genome structure of T4 bacteriophage. Bacteriophage T4 of Escherichia coli is one of the most studied phages. chromosome structure in phage t4. Bacteriophage T4 consists of a prolate head with icosahedral ends and a bilayered tail that has a hexagonal baseplate and fibres at its distal end 3.The phage recognizes a ⦠It is the polymerization of these transmembrane domains that leads to the formation of lesions in the ⦠Here, we use skinny E. coli minicells as a host, along with cryo-electron tomography and mutant phage virions, to visualize key structural intermediates during initiation of T4 infection. The wac gene product (gpwac) or fibritin of bacteriophage T4 forms the six fibers that radiate from the phage neck. Research into it has led to numerous contributions to phage biology and biochemistry. The experimental system is based on genetic crosses of different mutant strains of bacteriophage T4, a virus that infects the bacteria E. coli . One type of mutation in the T4 bacteriophage identified by researchers in phage genetics by the 1950s was known as r (for rapid ), which caused the phage to destroy bacteria more quickly than normal. Coding about 300 gene products, this double-stranded DNA virus is the best-understood model in phage study and modern genomics and proteomics. The book is a sequel to the 1983 edition and is organized into six major sections: DNA metabolism, regulation of gene expression, phage morphogenesis, structure and function of selected proteins, host-phage interactions, and experiments in T4 molecular genetics. This bacteriophage lecture explains the structure and properties of bacteriophage T4. 1a).The portal nucleates the assembly of the hexameric capsomers each composed of six copies of the major capsid protein (gp23) into capsids. Abstract. Normal expectations would be that a molecular assembly occurs as a result of loss of energy. The action of exopolynucleotidases. Structure of Bacteriophage Schematic representation of main types of phages (Image source: Brock Biology of Microorganisms) Bacteriophage structures are diverse, but most of them share some common characteristics. I. The article (E pstein et al. 1) [6]. Enterobacteria phage T4 (Bacteriophage T4) Status. The head is bipyramidal hexagonal in shape and measures 950 x 650 Å. We report the crystal structure of the DNA packaging motor protein, gene product 17 (gp17), in bacteriophage T4. The 3.3-Å cryo-EM structure of the 860-Å-diameter isometric mutant bacteriophage T4 capsid has been determined. We show for the first Escherichia virus T4 is a species of bacteriophages that infect Escherichia coli bacteria. [pmc free article] The r mutants (rapid lysis) are easily distinguished by their large, sharp-edged plaques. Bacteriophage T4 provides an important model system for studying the mechanism of homologous recombination. proc natl acad sci u s a. Further, when 'K' was infected simultaneously by rII+ and rII, large plaques were formed, since rII+ helps in lysis so that rII may express. The wild type phage do not lyse and release progeny phage as rapidly as the r mutants. The structure of the DNA of bacteriophage phi-X174. The contents of head are enclosed by a membrane (capsid) about 35 Å thick. The elongated isocahedral head of T4 phage contains linear double-stranded DNA genome about 169 kbp long and encodes 289 proteins including two accesory proteins, HOC (highly antigenic outer capsid proteins) and SOC (small outer capsid proteins). Binding of SOC stablizes the capsid and resist osmotic shocks. The structures of T4 gp41 helicase, gp61 primase, and T4 DNA ligase are unknown, structures from bacteriophage T7 proteins are discussed instead. However, a virus has to be poised in a high-energy form to fight its way into a ⦠Introduction. The morphology of the bacteriophages has been best studied by electron microscopy. 1964 mar; 4:93â106. The virion of T-even phage is binal or tadpole like structure with a polyhedral head connected to a helical tail through a short collar. WT T4 has a prolate capsid characterized by triangulation numbers (T numbers) T end = 13 for end caps and T mid = 20 for midsection. The tail has an inner hollow tube called core, surrounded by a contractile sheath which consists of 24 annular rings. protein cylinders, at one end of w hich is the baseplate and. i. circularity of the linkage map. After the cell lysis, the gpwac fibers function as part of an environmental sensing device that retains the LTFs in a retracted configuration ⦠Beginning in 1954, Benzer put the T4 rII system to use, creating and crossing hundreds of r mutants and developing an increasingly detailed map of the structure of the rII gene. To better understand the functionality of T4 DNA replication, in depth structural analysis will ⦠biophys j. Phage T4 has provided countless contributions to the paradigms of genetics and biochemistry. Ranging from viral RNA polymerase, commonly found in phages, to thymidylate synthase, ⦠1. A structural model built for gp23 using its similarity to gp24 showed that the phage T4 major capsid protein has the same fold as that found in phage HK97 and several other icosahedral bacteriophages. Folding of gp23 requires the assistance of two chaperones, the E. coli chaperone GroEL and the phage coded gp23-specific chaperone, gp31. The wild type phage T4 (rII+) will make small and fuzzy plaques, both on B and K strains (Fig. Bacteriophage, also called phage or bacterial virus, any of a group of viruses that infect bacteria.Bacteriophages were discovered independently by Frederick W. Twort in Great Britain (1915) and Félix dâHérelle in France (1917). Viral genomes are packaged into "procapsids" by powerful molecular motors. Its complete genome sequence of 168,903 bp encodes about 300 gene products. The portal of T4 (gp20) and of other phages is a dodecamer , .It is the first structure assembled in the head assembly pathway (Fig. The tail possesses a thin tail fibre (25 nm long) at its end which recognises the hosts. The head composed of about 2000 capsomeres arid encloses a tightly packed dsDNA (50 nm long). 1964 may; 51:775â779. Unlike T-even phage, it is a simple structure devoid of the tail sheath. Structure: The T-even phage (Fig. phage virion must undergo significant structural remodeling. The bacteriophage T4 capsid is an elongated icosahedron, 120 nm long and 86 nm wide, and is built with three essential proteins; gp23*, which forms the hexagonal capsid lattice, gp24*, which forms pentamers at eleven of the twelve vertices, and gp20, which forms the unique dodecameric portal vertex through which DNA enters during packaging and exits during infection. Molecular Biology of Bacteriophage T4 highlights the value of this biological system as a research and teaching tool. The heads of phage T4 are assembled on the membrane. A mutation in the major capsid prot ⦠Meaning of Bacteriophages: Viruses which attack or parasitize the bacterial cells are known as ⦠In studies of phage evolution, phage T4 along with phage T2 and T6 form the original members of the T-even family of bacteriophage, which now includes many members that infect many other species of bacteria besides E. coli. The bacteriophage T4 tail is composed of tw o concentric. 1963) described the phenotypes of 130 conditional-lethal mutants of T4, 69 amber mutants, and 61 temperature-sensitive (ts) lethal mutants and presented a genetic map of these mutations. 17-11 b) Extreme condensation of DNA to fit into phage head (5000X) The first steps of phage infection require interactions between the phage receptor-binding proteins (RBPs) 2 (1, 2) and the receptors at the host cell surface.Although some RBPs are located at the tip of fibers (), others belong to an elongated structure, the tail spike (4, 5).In bacteriophages infecting the Gram + bacterium Lactococcus lactis such as p2 (936 group), TP901-1, ⦠There is a hole in capsid through which passes this narrow neck portion expanding into a knob like structure inside. The T-even phages (T 2, T 4, T 6) are homologous and much of our knowledge about bacteriophages is based on them, particularly T 4 phage. Synthesis of T4 late proteins a) phage structural proteins b) proteins that help in assembly but are not part of the final capsid c) proteins involved in cell lysis and phage release 5. Dharmalingam K, Goldberg EB. As one of the best studied of phage types, the biology of phage T4, like that of phage λ, may be considered archetypical. For phage T4, the most obvious change is the contraction of its tail. The head is an elongated, bi-pyramidal, hexagonal like prism consisting of ⦠Bacteriophage T4 has a very efficient mechanism for infecting cells. It is a pentamer of the large terminase, 3 gene product (gp) 4 17, which, when assembled on the prohead, forms a continuous channel with the portal. [pmc free article] thomas ca, jr, rubenstein i. the arrangements of nucleotide sequences in t2 and t5 bacteriophage dna molecules. The viral particle is naked icosahedral and tailed. Restriction in vivo. The T4 virion is assembled from a series of modular components including a large elongated head (â¼111 × 78 nm), a tail structure (â¼113 × 16 nm) that can be triggered to contract, and an intricate baseplate that incorporates the tail triggering mechanism and also the 6 long tail fibers that specifically bind to receptors on the surface of the host bacteria (reviewed in Leiman et al. The T4 phage is tadpole shaped and consists of the five important sub-structures such as the head, head-tail connector, tail base plate and fibers (Fig. Bacteriophage T7 (or the T7 phage) is a bacteriophage, a virus that infects bacteria.It infects most strains of Escherichia coli and relies on these hosts to propagate. 1979 Jul 30; 96 (2):393â403. It consists of dsDNA molecule protected by a protein coat made up of numerous facets. Assembly of T4 a) Fig. 2003). [Google Scholar] FIERS W, SINSHEIMER RL. The T4 transcriptional pattern reflects its dependence on the host RNA polymerase and the use of phage-encoded proteins that sequentially modify RNA polymerase; transcriptional activator proteins, a phage sigma factor, anti-sigma, and sigma decoy proteins also ⦠1. Structure: The virion of T-even phage is binal or tadpole like structure with a polyhedral head connected to a helical tail through a short collar. The head composed of about 2000 capsomeres arid encloses a tightly packed dsDNA (50 nm long). In this article we will discuss about the mapping of rII locus in T4. T4-based phage display combined with affinity chromatography can be applied as a new method for bacteriophage purification.
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