Penicillinase messenger half-life

Because of the critical importance of the penicillinase messenger half-life in pinpointing likely models of penicillinase regulation, Imsande and Davies reexamined the whole question. Their results (Imsande [2], Imsande and Davies, unpublished results quoted in reference [2]) point to a rapid inactivation of the penicillinase synthetic capacity of cultures inhibited either by actinomycin or rifampicin, both for the constitutive strain 569/H and for the strain 569 after induction. They concluded that the half-life of the functional messenger was about 2 to 2.5 minutes in each case. This is similar to the turnover of other bacterial messenger RNA s that have been measured. 

Yudkin [86] offered evidence that the messenger half-life for penicillinase differed in induced and constitutive mutant strains of B. licheniformis 749, based on penicillinase synthesis after treatment with actinomycin. In induced cultures the half-life was about 2 to 3 minutes, while in the constitutive mutant the half-hfe appeared to be 10 minutes. Yudkin [87] did not obtain similar results with other constitutive strains, and this high value is therefore not substantiated. Davies [84,88], using both actinomycin and rifampicin, inferred messenger half-lives of about 4.7 minutes for both induced and constitutive penicillinase synthesis. Subsequent experiments (Davies and Collins, in preparation) have given shorter estimates of 2 to 4 minutes for penicillinase messenger half-life during vanadate-induced synthesis. 

In this case, where the messenger half-life is about 2 minutes (see Section III, A, 6), the long duration of the increased penicillinase synthesis must indicate prolonged penicillinase messenger synthesis and a lag in the production or action of new repressor. A key experiment is illustrated in Fig. 5. Csanyi [29] tested the specific activity of cells in-... 

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