Escherichia coli traD(Ts) mutant temperature sensitive for assembly of RNA bacteriophage MS2.

We report here a study on the temperature-sensitive conjugational transfer-deficient mutant Escherichia coli JCFL39, carrying a traD(Ts) mutation, which is also temperature sensitive for group I RNA phages (MS2, f2, and R17). It is shown that, when the mutant was infected with MS2 at 42 degrees C, phage RNA replicated; a 27S MS2 RNA and phage proteins were synthesized. However, neither PFU nor physical MS2 particles were formed, showing that phage assembly was inhibited. In addition, the high temperature affected the membranes of the host mutant: the mutant was hypersensitive to chemicals, and the electrophoretic pattern of the membranal proteins was modified. We suggest that the pleiotropic effects of the traD mutation on MS2 assembly and DNA transfer during conjugation were a result of the changes in the membrane of the mutant.