Analysis of gene function of bacteriophage phi 29 of Bacillus subtilis: identification of cistrons essential for viral assembly

Abstract

Restrictive infection of B. subtilis by suppressor sensitive (sus) mutants of .vphi.29 was used to search for cistrons that function in viral assembly. The products of cistrons 7, 9, 10 and 16 are necessary for head morphogenesis. The neck upper collar protein P10 and the tail protein P9 must be present for DNA packaging to occur. The protein P7 must be present for phage-related particles to form. A prohead-like particle was isolated during 16- restrictive infection. The particle is composed of proteins Hd, P10, F and P7. P16 must function for DNA-filled particles to accumulate. A DNA containing particle produced in the absence of the cistron 11 product may be an intermediate in the .vphi.29 assembly pathway. The protein P13 interacts with P9 and P11 to form a stable DNA-filled particle. The products of cistrons 2 and 3 are essential for viral DNA synthesis and in their absence virus-related particles are not detected.