A precursor of the neck appendage of Bacillus subtilis phage ø29

Abstract

The cleavage of precursor proteins to polypeptides of smaller molecular weight is a mechanism involved in the morphogenesis of the head and DNA encapsulat- ion in T4 [l-4]. In this paper we present evidence which indicates the existence of a precursor in the synthesis of the protein which forms the neck appen- dages of the Bacillus subtilis phage a29 [S] . Pulse- chase experiments indicate that the neck appendage protein (NPl), of molecular weight 80 000, is syn- thesized as a precursor (P-NPI) with a molecular weight about 90 000, and tryptic peptide analysis of both proteins (P-NPl and NPI), show that they contain very similar peptides. These results indicate a precursor-product relationship of proteins P-NPl and NPI. Infection under nonpermissive conditions with temperature-sensitive mutants in cistron B, the gene coding for the neck appendage protein precursor [6] , which have a clear plaque phenotype, gives place to the accumulation of protein P-NPI in higher amount than that present after normal phage infection. Some evidence for the existence of a precursor of the @29 neck appendage protein has been given by Anderson and Reilly [7] .