Control of phage λ development by stability and synthesis of cll protein: Role of the viral clll and host hflA, himA and himD genes

Abstract

The cll protein of bacteriophage λ has a decisive role in the regulatory switch between the lysogenic and lytic pathways of viral development. Recent work has indicated that cll may be the primary control function providing for the initial partition between the two pathways, with other host and viral regulatory genes acting to determine the levels of cll in an infected cell. We have studied the synthesis and stability of cll protein with two experimental systems, phage infection and a cll-producing plasmid. We have found that the stability of cll is controlled by the host hflA and viral clll genes; hflA protein facilitates degradation of cll, whereas clll protects cll. The synthesis of cll appears to be under the positive control of the host himA and himD genes. We conclude that posttranscriptional regulation of cll by host and viral genes is critical for the choice of a developmental pathway.