Synthesis of Bacteriophage φ29 Proteins in Bacillus subtilis

Abstract

Seventeen bacteriophage φ29 proteins were detected in ultraviolet light-irradiated Bacillus subtilis by autoradiography of polyacrylamide slab gels. The appearance of φ29 proteins occurred either before or concomitantly with viral DNA replication. Viral proteins detected early in the infectious cycle consisted of nine polypeptides ranging from 5,200 daltons to 54,000 daltons. Two of the early proteins were identified as, respectively, the major capsid protein and the protein comprising the filaments which extend from the head of the virus. Late φ29 proteins were composed of eight polypeptides ranging from 14,000 daltons to 95,000 daltons. Only three late proteins were noncapsid proteins. Among the early proteins, six were synthesized at diminishing rates late in the infectious cycle. One of the early proteins (protein 12) lacked histidine, whereas two (proteins 10 and 15) lacked tryptophan. Among the 17 proteins detected, 10 were viral noncapsid proteins. The amount of viral genetic information required to code for the 17 proteins detected in these experiments (81% of the potential genetic information of φ29 DNA) compares favorably with the genetic information detected as mRNA in a previous report, 85% of the potential information on the φ29 chromosome.