Genes VI, VII and IX of bacteriophage M13: identification of their products as minor capsid proteins.

In earlier work, two new minor capsid proteins of molecular weight 3500 (C-protein) and 11,500 (D-protein) were detected in M13 virions. To determine their genetic origin, differential amino acid labeling, amino acid analysis and Edman degradation analysis were performed on these proteins. The data demonstrate that D-protein is the product of gene VI whereas C-protein is composed of both the proteins specified by gene VII and the recently discovered gene IX. by selective labeling with arginine, the number of C and D protein molecules present in M13 virions was estimated to be 5 D-protein and approx. 6-8 C-protein molecules. From synthesis studies of C-protein in E. coli minicells which harbor either wt- or amber mutant RF molecules, evidence is presented that genes V, VII and IX form an operon.