Siersma P W, Lederberg S
J Bacteriol. 1970 Feb;101(2):398-407. doi: 10.1128/jb.101.2.398-407.1970.
The methylation of ribosomal and transfer ribonucleic acid (RNA) synthesized after the induction of a hydrolase for S-adenosylmethionine by phage T3 infection is reducible to 50% of the methylation of RNA in uninfected cells. Hypomethylated ribosomal RNA is found in 70S particles that dissociate in 100 mum Mg(++) to yield only 30S and 50S subunits. By this criterion, the omitted methyl groups apparently are not required for ribosomal maturation or stability. The rate of production of alkaline phosphatase in a phosphatase amber mutant was examined after phage infection in the presence and in the absence of streptomycin to determine the effect on the translation process consequent to S-adenosyl-l-methionine (SAM) hydrolase induction. Significant increases in the rates of phosphatase production were found when ultraviolet-inactivated T3 or streptomycin was added. The effects were cumulative when the cells were treated with both bacteriophage and the drug. Ultraviolet-inactivated T7, a phage closely related to T3 but which does not produce the SAM hydrolase, did not enhance the rate of alkaline phosphatase production. We suggest that the production of SAM hydrolase affects the stability of the translation process by the observed hypomethylation or by mechanisms concerning polyamine metabolism.
噬菌体T3感染诱导S-腺苷甲硫氨酸水解酶后合成的核糖体核糖核酸和转移核糖核酸（RNA）的甲基化程度可降至未感染细胞中RNA甲基化程度的50%。在100 μM Mg(++)中解离的70S颗粒中发现了低甲基化的核糖体RNA，其仅产生30S和50S亚基。据此标准，缺失的甲基显然不是核糖体成熟或稳定所必需的。在存在和不存在链霉素的情况下，噬菌体感染后检测了磷酸酶琥珀突变体中碱性磷酸酶的产生速率，以确定S-腺苷-L-甲硫氨酸（SAM）水解酶诱导对翻译过程的影响。当加入紫外线灭活的T3或链霉素时，发现磷酸酶产生速率显著增加。当细胞同时用噬菌体和药物处理时，这些影响是累积的。紫外线灭活的T7是一种与T3密切相关但不产生SAM水解酶的噬菌体，它不会提高碱性磷酸酶的产生速率。我们认为，SAM水解酶的产生通过观察到的低甲基化或通过与多胺代谢有关的机制影响翻译过程的稳定性。
