Protein synthesis following infection of the blue-green alga Plectonema boryanum with the temperate virus SPI and its ts mutants

Abstract

The structural proteins of the purified phage and proteins synthesized in virus-infected cells were examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and subsequent autoradiography. A total of 24 viral-induced proteins were identified, 12 of which are present in the mature virus. The kinetics of synthesis of the various viral proteins demonstrates the presence of “early” and “late” genes. Specific suppression of host protein synthesis by the infecting phage takes place late in the infection cycle. Analysis of the proteins synthesized at the nonpermissive temperature by phage temperature-sensitive ( ts) mutants demonstrates that some of the viral genes have complex pleiotropic effects on viral protein synthesis. The results suggest the presence of positive regulatory genes, and of specific genes involved in the shutoff of host protein synthesis.