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Bacteriophage P2 head morphogenesis: Cleavage of the major capsid protein

1973; Elsevier BV; Volume: 53; Issue: 1 Linguagem: Inglês

10.1016/0042-6822(73)90461-3

1096-0341

Judith A. Lengyel, Richard Goldstein, Margaret Marsh, Melvin G. Sunshine, Richard Calendar,

Bacterial Genetics and Biotechnology

The protein products of four P2 head genes have been identified, and their molecular weights estimated by migration in SDS polyacrylamide gels. The product of the N gene is a protein with a molecular weight of 44,000, which is cleaved to give the major capsid protein, N∗, with a molecular weight of 36,000. Two other protein components of the head may also be cleavage products of the N protein. Coupled to the cleavage of the N protein is the cleavage of the O gene product from a 30,000 molecular weight protein to material of less than 17,000 molecular weight. The P gene product has been identified and is bound to rapidly sedimenting material, possibly membrane. The products of genes M, O, and P are not detected in mature phage heads. Mutants in head genes L, M, P, and Q can synthesize head-like structures under nonpermissive conditions, but mutants in genes O and N cannot. A model of P2 head assembly is presented in which the O and N gene products assemble and are cleaved to give a semistable head precursor. This precursor is then acted upon by the four other head gene products to form the mature head.