Assembly and attachment of bacteriophage T4 tail fibers.

Abstract

AbstractBacteriophage T4 tail fibers are rodlike structures with a contour length of about 1400 Å, a diameter of about 45 Å, and a total mass of about 600,000 daltons. The assembly of the tail fibers and their subsequent attachment to the phage particle are under the control of 8 phage‐induced proteins. The gene control and molecular weight of each protein are known. The sequence of gene‐controlled steps has been determined by the characterization of intermediates that accumulate when various steps are blocked by mutation. The protein composition of the fibers and their precursors has been determined by purification and electrophoretic analysis.Four of the eight gene products are structural components of the tail fiber. These proteins are P34 (150,000 daltons, 2 copies), P37 (120,000 daltons, 2 copies), P35 (40,000 daltons, 1 copy), and P36 (24,000 daltons, 2 copies). The wac (whisker antigen control) gene product is a structural component of the phage whiskers. The remaining three gene products, P38, P57, and P63, are not structural components of the phage particle. Both P63 and the wac gene product promote the attachment of tail fibers to the phage particle. P63 has been shown to act catalytically. Both P38 and P57 are somehow involved in the folding of the major tail fiber structural proteins (P37 and P34). The normal requirement for P38 and P57 functions can be bypassed by secondary mutations.