Synthesis and degradation of early mRNA in lambda phage

Using two different Escherichia coli mutants defective in elongation factors EFG and EFTs required for peptide synthesis, lambda phage with or without a tof mutation was analysed for synthesis of early mRNA by DNA-RNA hybridization technique. (1) In CP78G carrying temperature-sensitive elongation factor G, shift-up to high temperature (41 degrees C) in the middle of phage infection did not affect early mRNA synthesis with lambdatof+ phage but did inhibit it with lambdatof- phage. (2) In HAK88 carrying temperature-sensitive elongation factor Ts, shift-up to 41 degrees C dropped total cellular RNA synthesis to below 10-20 percent of the control in the presence or absence of phage infection (stringent control). Under such a condition for suppressed protein synthesis, lambda early mRNA synthesis was completely blocked with both tof+ and tof- phage infection. Thus, stringent control seems to exert its effect on lambda early mRNA synthesis. (3) Addition of chloramphenicol, which is known to relax the stringent control of RNA synthesis, to the culture of phage-infected HAK88 at 41 degrees C resulted in full recovery of tof+-mRNA synthesis, but only in partial recovery to tof --mRNA synthesis. (4) Analysis of the stability of lambda mRNA indicated an exponential decay, and a halflife of tof --mRNA of 6 min when that of tof+-mRNA was 13 min at 37 degrees C.