Abstract
Bacteriophage T2 is unusual in that its DNA contains 5-hydroxymethyl-cytosine (hm5C) in place of cytosine; in addition, hm5C is further modified by glucosylation (Revel and Luria, 1970). Phage T2 DNA also contains the methylated base, N6-methyladenine (m6A), and these are produced as a post-replicational modification by a phage induced DNA adenine methylase. Mutants which do not glucosylate their DNA, designated gt−, have been isolated. From these it has been possible to obtain mutants in the gene (dam) specifying the phage DNA methylase activity. Thus, parental phage T2 gt− dam+ and successive mutant strains, T2gt−damh and T2gt−damh dam-1, differ in their m6A contents; respectively 0.7, 2.3 and 0.05% of the adenine residues are m6A (Hattman, 1970; Revel and Hattman, 1971). Apparently the host enzyme is unable to methylate hm5C-containing DNA. Whereas the host DNA adenine methylase recognizes the sequence, G-A-T-C (Lacks and Greenberg, 1977; Hattman et al., 1978a), the phage dam+ and damh enzymes appear capable of methylating G-A-T and G-A-(T/C), respectively (Hattman et al., 1978b; Brooks and Hattman, 1978).
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References
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Hattman, S., Iannotti, A., Schlagman, S. (1982). Effect of N6-methyladenine (m6A) content in DNA on spontaneous reversion in non-glucosylated phage T2 gt—: Evidence for base analog mutagen activity. In: Biochemistry of S-Adenosylmethionine and Related Compounds. Palgrave Macmillan, London. https://doi.org/10.1007/978-1-349-06343-7_36
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DOI: https://doi.org/10.1007/978-1-349-06343-7_36
Publisher Name: Palgrave Macmillan, London
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