Molecular cloning of the T4 genome: organization and expression of the tail fiber gene cluster 34--38.

Abstract

lambda T4 derivatives that carry T4 tail fiber genes 34-38 have been isolated and characterized by genetic, structural and functional analysis. 32 lambda T4 recombinants were identified by a marker rescue screen of 310 lambda T4 clones generated by restriction of partial cytosine-containing T4 DNA with either HindIII or EcoRI and ligation into appropriately cleaved lambda vectors. These tests defined 15 recombinant classes with respect to the contiguous stretches of genome recovered. Restriction enzyme structural analysis identified 7 HindIII fragments and 7 EcoRI fragments, established a restriction map covering about 11 kb, and indicated the orientation of the DNA inserts within the lambda vectors. The cloned tail fiber genes are expressed efficiently from lambda promoters and complement in vivo T4 phage carrying amber mutations in the tail fiber genes. Polypeptides corresponding to gp34--gp38 have been detected by SDS polyacrylamide gel electrophoresis of 35S-labeled extracts of appropriate lambda T4 recombinant infected UV-treated host cells. The genetic, structural and functional maps of the T4 tail fiber gene cluster have been correlated, and provide a rational approach to genetically directed DNA sequence analysis of genes 34--38 and their mutant variants that affect the assembly, structure and function of the tail fibers.