ASSEMBLY OF BACTERIOPHAGE T4 TAIL FIBERS - SEQUENCE OF GENE PRODUCT INTERACTION

Intermediates in bacteriophage T4 tail fiber assembly, which accumulate in cells infected with mutants blocked at various stages of tail fiber formation, have been fractionated by velocity sedimentation and characterized using serological analysis, assays of activity for in vitro phage assembly, and electron microscopy. The results provide information on the gene control of three fiber-related structures found in lysates of wild-type-infected cells: a 10 s component identified as the complete tail fiber, a 9 s component of unknown morphology whose formation requires the function of gene 34, and an 8 s rod-shaped structure, half the length of the complete fiber, whose formation requires the function of genes 35, 36, 37 and 38. The 9 s and 8 s structures can combine, in unknown proportions, to form the complete fiber. Two precursors of the 8 s component have been identified; both also sediment at about 8 s and resemble half fibers. The first is the product of genes 37 and 38. Gene 36 function converts the first precursor to the second, with the addition of a new antigenic determinant. Gene 35 function converts the second precursor to a form capable of combining with the 9 s component. Tail fiber assembly proceeds independently of the formation of the rest of the phage particle; completion of the fiber is a prerequisite for its attachment to the phage. © 1969.