Molecular cloning of the T4 genome: Organization and expression of the tail fiber gene cluster 34–38

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Abstract
λT4 derivatives that carry T4 tail fiber genes 34–38 have been isolated and characterized by genetic, structural and functional analysis. 32 λT4 recombinants were identified by a marker rescue screen of 310 λT4 clones generated by restriction of partial cytosine-containing T4 DNA with either HindIII or EcoRI and ligation into appropriately cleaved λ 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 λ vectors. The cloned tail fiber genes are expressed efficiently from λ 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 λT4 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.