Electron microscopic study of the structure of mutants of bacteriophage T4D defective in tail fiber genes

Abstract Defective, nonviable phage particles are produced upon infection of restrictive bacteria by amber mutants in genes 34, 35, 36, 37, 38, and 57 of bacteriophage T4D. Electron microscopic examination of these particles shows that they all have reduced numbers of tail fibers, while the other structural components appear normal. Unattached tail fiber fragments about half the length of normal fibers, were found in most lysates. Abundant free fiber fragments are produced by mutants in genes 34, 35, and 36, but not at all by a gene 37 mutant, suggesting that gene 37 controls the major structural element of the tail fiber. Short tail fibrils, probably a normal structural feature of phage T4D, are also described.