T phage

Hydroxymethyl)cytosine has been found in the DNA of the T2, T4 and T phages of . coli [277, 278]. A glycosyl-substituted 5- hydroxymethyl)-2 -deoxycytidylic acid was isolated from a T2, -f-phage [279]. 

Hosoda, J., and R. Cone. 1970. Analysis of T phage proteins, I. Conversion of precursor proteins into lower molecular weight peptides during normal capsid formation. Proc. Nat. Acad. Sci. U.S.A., 66 1275. 

When this work was begun in 1966, conditions were not known for obtaining reasonable stimulation of cell-free peptide synthesis with E. coU DNA. The systems in use at that time were effective only when employed in conjunction with T-phage DNA [119,120]. Since the lac operon could be obtained only in E. call or related lysogenic phage DNA s, the first task was to develop a suitably responsive system. This was accomplished by varying the components and their concentration to achieve a maximum of E. call DNA-directed peptide synthesis measured by the incorporation of C-leucine. Conditions were ultimately found where coli DNA stimulated abut 0.7 m/imole of leucine incorporation per milligram of total protein in the cell-free system [121]. 

Morphologists postulated for many years that the transfer of information from DNA to protein involves a form of nuclear RNA that migrates from nucleus to cytoplasm. This hypothesis found some concrete support as molecular biology developed. At first, it was found that a small fraction of bacterial RNA has a base composition identical to DNA in bacteria infected with T phage. The synthesis of DNA-depend-ent RNA was demonstrated in bacterial preparations and in mammalian nuclei. Triphosphate ribosides (UTP, GTP, CTP, and ATP) are required precursors for the synthesis of the new polynucleotide. Double-stranded DNA serves as a template in the reaction, and an RNA polymerase catalyzing the polymerization of the ribonucleotide was partially purified from both the bacterial and mammalian systems. 

Harm, W., 1967, Differential effects of acriflavin and caffeine on various ultraviolet-irradiated Escherichia coli strains and T, phage, Mutat. Res. 4 93-110. 

Increase in enzymic activity of the infected cell. An increase in enzymic activity of the infected cell is contrary to the observations recorded above, and, indeed, with the exception of an enhancement of deoxyribonuclease, the activities of the bacterial enzymes appear to remain constant after infection of E. coli with the T phages (225a,227,227a). Since the enzymes appear to retain activity after infection, this suggests that the virus interferes with the synthesis of new enzymes, as well as RNA and protein, perhaps by diverting energy and metabolites from normal synthetic pathways to pathways of virus synthesis. 

Pardee and co-workers (225,225a,227,227a) have investigated the activity of 9 bacterial enzymes after infection of E. coli with various T phages, i.e., apyrase, ribonuclease, deoxyribonuclease, alkaline and acid proteases, pyruvic oxidase, formic dehydrogenase, serine deaminase, and catalase. The difficulties of assay of labile enzymes in the broken cell systems are indicated by the early report of an increase in apyrase activity (225) which later was attributed to a technical defect in the... 

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