T4-Bacteriophage

Figure 5.11 Attachment of T4 bacteriophage particle to the cell wall of G. coli and injection of DNA (a) Unattached particle, (b) Attachment to the wall by the long tail fibers, (c) Contact of cell wall by the tail pin. (d) Contraction of the tail sheath and injection of the DNA.

Yang, X., Lee,J., Mahony, E. M., Kwong, P. D., Wyatt, R., and Sodroski.J. (2002). Highly stable trimers formed by human immunodeficiency virus type 1 envelope glycoproteins fused with the trimeric motif of T4 bacteriophage fibritin. J. Virol. 76, 4634-4642. 

Sinha NK, Morris CF, Alberts BM. Efficient in vitro replication of double-stranded DNA templates by a purified T4 bacteriophage replication system. J. Biol. Chem. 1980 255 4290-4293. 

Despite the diversity in the structures of viruses and the types of host cell that are infected, there are several basic steps in the life cycle of all viruses infection (penetration of the virion or its nucleic acid into the host cell), replication (expression of the viral genome), maturation (assembly of viral components into virions), and release (the emission of new virions from the host cell). Because viruses usually possess only enough genetic information to specify the synthesis of their own components, each type must exploit some of the normal metabolic reactions of its host cell to complete the life cycle. For this reason there are numerous variations on these basic steps. This point can be illustrated by comparing the life cycles of two well-researched viruses the T4 bacteriophage and the human immunodeficiency virus (HIV). 

The T4 bacteriophage (Figure 17K) is a large virus with an icosa-hedral head and a long, complex tail similar in structure to T2 (p. 573). The head contains dsDNA, and the tail attaches to the host cell and injects the viral DNA into the host cell. 

A FIGURE 1-6 Viruses must infect a host cell to grow and reproduce. These electron micrographs illustrate some of the structural variety exhibited by viruses, (a) T4 bacteriophage (bracket) attaches to a bacterial cell via a tail structure. Viruses that infect bacteria are called bacteriophages, or simply phages, (b) Tobacco mosaic virus causes a mottling of the leaves of... 

Figure 4-40 Illustrates the lytic cycle for T4 bacteriophage, a nonenveloped DNA virus that Infects E. coii. Viral capsid proteins generally are made In large amounts because many copies of them are required for the assembly of each progeny virion. In each Infected cell, about 100-200 T4 progeny virions are produced and released by lysis.

A fiber probe with a cone angle as small as 25° and a curvature radius of smaller than 10 nm has achieved a vertical resolution of less than 1 nm and a lateral resolution of 20 nm with a PSTM. Thus a T4 bacteriophage could be optically imaged at that resolution in the phase-sensitive detection mode with a modulation frequency of 5 kHz [76]. The size of the icosahedral head is 85 x 115 nm the diameter and the length of the tail are about 9 and 98 nm, respectively. Both head and tail of several dried T4-bacteriophages are clearly imaged and identified [76],... 

Figure 1.9, DNA distribution in a shallow CsCl gradient of A a GC-rich YAC (Yeast Artdicial Chromosome) and B of a GC-poor YAC, A and T4 bacteriophage DNAs were used as density markers. The intensities of the hybridization signals (left ordinate) and the buoyant densities (right ordinate) arc plotted against the fractions collected from the gradient. (From De Sario el al, 1995).

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