[Effect of Escherichia coli mutations affecting the transcription termination rho on the development of T-even phages]

The functionally active transcription termination factor rho is necessary for the T-even phages development. The inactivation of the factor by thermosensitive E. coli gene rho mutations results in blocking phage development. It should be noted that phages T2 and T4 require different levels of this factor's activity. The synthesis of some early proteins diminishes during factor rho inactivation and a number of proteins typical for a later stage are observed early in infection. Under the conditions of the factor rho being inactivated the synthesis of a number of proteins is weakened late in infection and the capside proteins maturation is impaired. Alongside with this the factor rho inactivation results in a sharp decrease of phage DNA replication in infected cells. The obtained data suggests that in the absense of functionally active factor rho all the proteins necessary for phage DNA replication are formed. Besides, this factor is directly involved in the process of T-even phages DNA replication. One may conclude that the inability of T-even phages to develop in mutant cells rho is to a greater extent due to the impairment in phage DNA replication than to its transcription. The possible role of the factor rho in the process of DNA replication is discussed.