Transcription termination factor rho and T-even phage development.

A functional factor rho is necessary for T-even phage development; phages T2 and T4 require different degrees of rho activity. The rho inactivation by ts-mutations in E. coli causes a reduction of some early protein synthesis and an early formation of some proteins normally typical of a later stage. Besides, it weakens the synthesis of some late proteins, impairs the capsid proteins maturation and sharply inhibits phage DNA replication in infected cells. However, in the absence of a functional rho all the proteins required for phage DNA synthesis the formed, indicating that this factor is directly involved in the process of T-even phage DNA replication. A number of rifampicin-resistant mutations supressing the rho 15 mutation and restoring the ability of cells to grow at high temperature were isolated. However these RNA polymerase mutations do not or only partially suppress the effect of rho mutations on T-even phage development and the phage DNA synthesis. The role of rho in DNA transcription and replication during bacteriophage development is discussed.