Bacteriophage T-even

Yanagida, M., Boy de la Tour, E., Alff-Steinberger, C. Kellenberger, E. 1970 Studies on the morphopoiesis of the head of bacteriophage T-even. VII. Multilayer polyheads. J. molec. Biol. 50, 35-58. 

Hydroxymethylcytosine (967) was isolated only in 1952 from the T-even bacteriophages of Escherichia coli, in which it occurs instead of cytosine in the 2-deoxyribonucleic acid (65MI21304). Of several syntheses described, the most convenient is probably that beginning with ethyl 4-amino-2-methylthiopyrimidine-5-carboxylate which is reduced by LAH to 4-amino-2-methylthiopyrimidin-5-ylmethanol followed by hydrolysis to 5-hydroxymethyl-cytosine (967) (B-68MI21302, B-68MI21306). 

Figure 16.1 Viruses vary in size and shape from the simplest satellite viruses (a) that need another virus for their replication to the T-even bacteriophages (d) that have developed sophisticated mechanisms for injecting DNA into bacteria. Four different virus particles are shown to scale.

Figure 1.18 The unique base in the DNA of the T-even bacteriophages, 5-hydroxymethyIcytosine. The site of glucosylation is shown.

Life and Death for Proteins Chaperonins and Proteasomes Sickle Cell Disease, Malaria, and Blood Substitutes The T-Even Bacteriophages Mitosis, Tetraploid Plants, and Anticancer Drugs... 

In addition to its function in catalysis, zinc often plays an important structural role, e.g., in the zinc finger transcriptional regulators (Fig. 5-38).k Zinc ions bind to insulin and stabilize its hexameric structure (Fig. 7-18)/ Six Zn2+ ions are present in the hexagonal tail plate of the T-even bacteriophage (Box 7-C) and appear to be essential for invasion of bacteria.131 In carnivores, the tapetum, the reflecting layer behind the retina of the eye of many animals, contains crystals of the Zn2+-cysteine complex. 

Cells of E. coli, when infected with T-even bacteriophage, convert dCMP to 5-hydro xymethyl-dC.MP l23i ... 

Bacteriophage, a virus infecting bacterial cells, has a structure somewhat different from those previously described. A head contains the nucleic acid and the viral DNA passes through a tail during the infection process. In the T-even phages (Fig. 1), the tad consists of a tube surrounded by a sheath and is connected to a thin collar al the head end and a plate at the tip end. The sheath is capable of contraction and the plate possesses pins and tail fibers, which are the organs of attachment of the bacteriophage to the. wall of the host cell. 

Becker and Hurwitz 94) have found that after infection of E. coli B with T-even bacteriophages a novel 3 -deoxynucleotidase activity appears. They purified the enzyme 2000-fold. In addition to its attack on 3 -deoxymononucleotides, the enzyme selectively removes the 3 -phos-phoryl groups from DNA. It does not attack 3 -ribonucleotides, 3 -phosphoryl groups of RNA, or 5 -phosphate esters. Like bacterial 5 -nucleotidases, this enzyme is markedly activated by Mg2+ and Co2+ and is inhibited by EDTA. The enzyme appears to be a phage-induced enzyme the activity rises early after injection with T-even phages and formation of the enzyme is blocked with chloramphenicol. 

Extracts of cells - of Escherichia coli infected with a T-even bacteriophage contain an enzyme deoxycytidylate hydroxymethylase which is not detected in uninfected cells it catalyzes the formation of 6 -(hydroxymethyl)-2-deoxyc3didylic acid from formaldehyde and 2-deoxycytidyUc acid in the presence of tetrahydrofolic acid and magnesium ions. In a large-scale experiment, 10.6 mg. of the barium salt was prepared. 

FIGURE 2.7 Life-reproductive cycle of a virus as illustrated by a T-even bacteriophage infecting a bacterial cell (a) dormancy, (b) adsorption, (c) penetration, (d) replication of new proteins and nucleic acids, (e) maturation, and (f) release and bursting of hold cell. 

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